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Govindaraju Ramkumar,1,* Sengodan Karthi,1,2,* Muthugounder S Shivakumar,1 Eliningaya J Kweka3,4 1Molecular Entomology Laboratory, Department of Biotechnology, Periyar University, Salem 636 011, Tamil Nadu, India; 2Department of Biochemistry, Centre for Biological Sciences, K.S. Rangasamy College of Arts and Science (Autonomous), Tiruchengode 637215, Tamil Nadu, India; 3Division of Livestock and Human Diseases Vector Control, Mosquito Section Tropical Pesticides Research Institute, Arusha, Tanzania; 4Department of Medical Parasitology and Entomology, Catholic University of Health and Allied Sciences, Mwanza, Tanzania*These authors contributed equally to this workCorrespondence: Eliningaya J KwekaDivision of Livestock and Human Diseases Vector Control, Mosquito Section Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, TanzaniaEmail pat.kweka@gmail.comBackground: Insecticide resistance among mosquito vectors for synthetic insecticides still remains a major problem for control efforts. This study assessed the ovicidal potential of crude solvent extracts from the medicinal plant Cipadessa baccifera comparatively to standard registered synthetic insect growth regulators (IGR) on freshly laid eggs of Culex quinquefasciatus.Method: Five plant extracts were prepared using different solvents. The batches of eggs were exposed to different concentrations of each solvent extract comparatively to synthetic IGR. The hatched eggs of Cx. quinquefasciatus were subjected to different concentrations. The first instars that emerged from the eggs were counted daily. The egg hatching inhibition was observed 24, 48 and 72 hrs post treatment. The desiccation median time (DT50 and DT90) was calculated.Results: The percent egg hatching inhibition was inversely proportional to the concentration of extracts. The morphological damage to the eggs was observed. Among five solvent extracts, acetone extracts showed the highest ovicidal activity. The changes in eggshell morphology were observed. The maximum ovicidal activity was observed in acetone extracts with DT50 value of 1.70 hrs (0.91–2.22). The methanol plant extract using gas chromatography-mass spectrometry identified 14 compounds.Conclusion: These results suggest that the acetone extracts of C. baccifera have the potential to be used as an ovicidal agent for controlling mosquito populations in aquatic stages. The biodegradability of the extracts has the advantage of being eco-friendly.Keywords: mosquito, egg hatching, insect growth regulators, ovicidal activity plant extracts

Ramkumar G, Karthi S, Shivakumar MS, Kweka EJ. Culex quinquefasciatus egg membrane alteration and ovicidal activity of Cipadessa baccifera (Roth) plant extracts compared to synthetic insect growth regulators. Res RepTrop Med. 2019;10:145– 151. The authors have advised that the current ethics approval section on page 150 is incorrect. The section should read: Ethics ApprovalThis study was approved and carried out by Department of Biotechnology, Periyar University, Salem-11.Read the original article

The microbial larvicides Bacillus thuringiensis var. israelensis (Bti) and Bacillus sphaericus (Bs) (Bacillales: Bacillaceae) are well known for their efficacy and safety in mosquito control. In order to assess their potential value in future mosquito control strategies in western Kenya, the current study tested the susceptibility of five populations of Anopheles gambiae complex mosquitoes (Diptera: Culicidae), collected from five diverse ecological sites in this area, to Bti and Bs under laboratory conditions. In each population, bioassays were conducted with eight concentrations of larvicide (Bti/Bs) in four replicates and were repeated on three separate days. Larval mortality was recorded at 24 h or 48 h after the application of larvicide and subjected to probit analysis. A total of 2400 An. gambiae complex larvae from each population were tested for their susceptibility to Bti and Bs. The mean (± standard error of the mean, SEM) lethal concentration values of Bti required to achieve 50% and 95% larval mortality (LC50 and LC95 ) across the five populations were 0.062  (± 0.005) mg/L and 0.797 (± 0.087) mg/L, respectively. Corresponding mean  (± SEM) values for Bs were 0.058 (± 0.005) mg/L and 0.451 (± 0.053) mg/L, respectively. Statistical analysis indicated that the five populations of An. gambiae complex mosquitoes tested were fully susceptible to Bti and Bs, and there was no significant variation in susceptibility among the tested populations.

© 2015 Kweka et al. Background: Mosquito larval source management (LSM) is likely to be more effective when adequate information such as dominant species, seasonal abundance, type of productive habitat, and land use type are available for targeted sites. LSM has been an effective strategy for reducing malaria morbidity in both urban and rural areas in Africa where sufficient proportions of larval habitats can be targeted. In this study, we conducted longitudinal larval source surveillance in the western Kenya highlands, generating data which can be used to establish cost-effective targeted intervention tools. Methods: One hundred and twenty-four (124) positive larval habitats were monitored weekly and sampled for mosquito larvae over the 85-week period from 28 July 2009 to 3 March 2011. Two villages in the western Kenya highlands, Mbale and Iguhu, were included in the study. Results: A total of 46,846 larvae were sampled, of which 44.1 % (20,907) were from abandoned goldmines, 30.9 % (14,469) from drainage ditches, 22.4 % (10,499) from swamps and 2.1 % (971) from hoof prints. In terms of land use types, 57.2 % (26,799) of the sampled larvae were from pasture and 42.8 % (20,047) were from farmland. Of the specimens identified morphologically, 24,583 (52.5 %) were Anopheles gambiae s.l., 11,901 (25.4 %) were Culex quinquefasciatus, 5628 (12 %) were An. funestus s.l. and 4734 (10.1 %) were other anopheline species (An. coustani, An. squamosus, An. ziemanni or An. implexus). Malaria vector dynamics varied seasonally, with An.gambiae s.s. dominating during wet season and An.arabiensis during dry season. An increased proportion of An. arabiensis was observed compared to previous studies. Conclusion: These results suggest that long-term monitoring of larval habitats can establish effective surveillance systems and tools. Additionally, the results suggest that larval control is most effective in the dry season due to habitat restriction, with abandoned goldmines, drainage ditches and swamps being the best habitats to target. Both farmland and pasture should be targeted for effective larval control. An increased proportion of An. arabiensis in the An. gambiae complex was noticed in this study for the very first time in the western Kenya highlands; hence, further control tools should be in place for effective control of An. arabiensis.

Background: In sub-Saharan Africa, malaria, transmitted by the Anopheles mosquito, remains one of the foremost public health concerns. Anopheles gambiae, the primary malaria vector in sub-Saharan Africa, is typically associated with ephemeral, sunlit habitats; however, An. gambiae larvae often share these habitats with other anophelines along with other disease-transmitting and benign mosquito species. Resource limitations within habitats can constrain larval density and development, and this drives competitive interactions among and between species. Methods. We used naturally occurring stable isotope ratios of carbon and nitrogen to identify resource partitioning among co-occurring larval species in microcosms and natural habitats in western Kenya. We used two and three source mixing models to estimate resource utilization (i.e. bacteria, algae, organic matter) by larvae. Results: Laboratory experiments revealed larval δ§ssup§13§esup§C and δ§ssup§ 15§esup§N composition to reflect the food sources they were reared on. Resource partitioning was demonstrated between An. gambiae and Culex quinquefasciatus larvae sharing the same microcosms. Differences in larval δ§ssup§13§esup§C and δ§ssup§15§ esup§N content was also evident in natural habitats, and Anopheles species were consistently more enriched in δ§ssup§13§esup§C when compared to culicine larvae. Conclusions: These observations demonstrate inter-specific resource partitioning between Cx. quinquefasciatus and An. gambiae larvae in natural habitats in western Kenya. This information may be translated into opportunities for targeted larval control efforts by limiting specific larval food resources, or through bio-control utilizing competitors at the same trophic level. © 2013 Gilbreath et al.; licensee BioMed Central Ltd.

Background: The effective measures for the control of malaria and filariasis vectors can be achieved by targeting immature stages of anopheline and culicine mosquitoes in productive habitat. To design this strategy, the mechanisms (like biotic interactions with conspecifc and heterospecific larvae) regulating mosquito aquatic stages survivorship, development time and the size of emerging adults should be understood. This study explored the effect of co-habitation between An. gambiae s.s. and Cx. quinquefasciatus on different life history traits of both species under different densities and constant food supply in the habitats of the same size under semi-natural conditions. Methods. Experiments were set up with three combinations; Cx. quinquefasciatus alone (single species treatment), An. gambiae s.s. alone (single species treatment); and An. gambiae s.s. with Cx. quiquefasciatus (co-habitation treatment) in different densities in semi field situation. Results: The effect of co-habitation of An. gambiae s.s. and Cx. quinquefasciatus was found to principally affect three parameters. The wing-lengths (a proxy measure of body size) of An. gambiae s.s. in co-habitation treatments were significantly shorter in both females and males than in An. gambiae s.s single species treatments. In Cx. quinquefasciatus, no significant differences in wing-length were observed between the single species and co-habitation treatments. Daily survival rates were not significantly different between co-habitation and single species treatments for both An. gambiae s.s. and Cx. quinquefasciatus. Developmental time was found to be significantly different with single species treatments developing better than co-habitation treatments. Sex ratio was found to be significantly different from the proportion of 0.5 among single and co-habitation treatments species at different densities. Single species treatments had more males than females emerging while in co-habitation treatments more females emerged than males. In this study, there was no significant competitive survival advantage in co-habitation. Conclusion: These results suggest that co-habitation of An. gambiae s.s. and Cx. quinquefasciatus in semi-natural conditions affect mostly An. gambiae s.s. body size. Hence, more has to be understood on the effects of co-habitation of An. gambiae s.s. and Cx. quinquefasciatus in a natural ecology and its possible consequences in malaria and filariasis epidemiology. © 2012 Kweka et al; licensee BioMed Central Ltd.

Background: The emergence of insecticide resistance and its spread through populations of malaria vectors has decreased the number of insecticides available for control. Insecticide resistance has been observed in vector populations across sub-Saharan Africa in malaria endemic areas. Therefore, new compounds with different modes of action are needed that can be used in the management of resistance. The current study assessed the bioefficacy of the new indoor residual spray formulation, VECTRON™ T500 against Klypson 500 WG and water against laboratory reared and wild populations of Anopheles gambiae s.l.. The comparative experimental hut trial was implemented between June 2022 and December 2022 to determine the efficacy of VECTRON™ T500, containing the active ingredient (ai) broflanilide as a 50 % wettable powder (WP). The efficacy of VECTRON™ T500 was compared with a positive control, Klypson 500 WG, a wettable granule (WG) formulation that contains 50 % clothianidin. Cement and mud walls were sprayed with VECTRON™ T500, Klypson 500 WG with water sprayed as a negative control. The two insecticides and negative control were evaluated monthly for six months against laboratory and the field-derived An. gambiae s.l. using the standard WHO cone bioassays. Each wall had two cones on each day of testing. VECTRON™ T500 was sprayed on both surface types at a rate of 100mg ai/m 2 whilst Klypson 500 WG was applied at a rate of 300 mg ai/m 2 . For both wall surface types, the vector from the laboratory-reared and the wild populations exhibited a low knockdown effect to both VECTRON™ T500 and Klypson 500 WG. A total of 3,840 mosquitoes were used of which 2,880 (75 %) were susceptible colony of An. gambiae s.s. and 960 (25 %) were wild An. gambiae s.l.. The VECTRON™ T500 induced a mortality of 97.8 %-98.1 % in the laboratory population and 83.2-95.0 % wild population mosquitoes on cement and mud-walled huts respectively while Klypson 500 WG ranged from 89.6-99.0 % for wild and 99.0-99.3 % for the laboratory population mosquitoes on cement and mud walls respectively. The knockdown due to VECTRON™ T500 was 7.08 % in the sixth month, while for Klypson 500 WG was 16.04-17.50 %. The monthly wall cone bioassay mortality with VECTRON™ T500 remained over 80 % for 6 months post-spraying for both laboratory and wild populations. The findings of this study have shown VECTRON™ T500 to have extended efficacy against malaria vector mosquitoes when applied to cement and mud walls. The evaluated new IRS formulation, VECTRON™ T500, performed equally with the positive control, Klypson 500 WG, regarding its impact on vector mortality., Competing Interests: Declaration of competing interest The authors declare to have no known competing interests., (Copyright © 2024. Published by Elsevier B.V.)

Mosquitoes are important vectors of several arthropod-borne diseases, which remain a priority for epidemiological research. Mosquito vector control strategies have traditionally relied on chemical insecticides such as synthetic pyrethroids. However, the indiscriminate use of pesticides has resulted in the development of resistance in many mosquito species. In insects, resistance evolves primarily through the overexpression of one or more gene products from the cytochrome P450, carboxylesterase, and glutathione superfamilies. The current study examined the expression of cytochrome P450 CYP6M2, CYP6AA7, CYP6Z2, CYP9J34, α-Esterase, Esterase B1, and neuroactin genes in larvae and adults of a permethrin-resistant (PerRes) and susceptible (Sus) Culex quinquefasciatus strains. The results showed that the CYP6AA7 gene was overexpressed (10-fold) in larvae and adults with PerRes (p < 0.01) followed by CYPJ34 (9.0-fold) and CYP6Z2 (5.0-fold) compared to the Sus, whereas fewer changes in CYP6M gene expression were observed in PerRes adults (p < 0.05), and no expression was found in larvae. The esterase gene was overexpressed in PerRes larvae (9.0-fold) followed by adults (2.5-fold) compared to the susceptible strain. Based on data, the present study suggests that cytochrome P450, CYP6AA7, CYP6Z2, CYP9J34, α-Esterase, Esterase B1, and neuroactin genes were involved in permethrin resistance in larval and adult Cx. quinquefasciatus., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Despite high levels of pyrethroid resistance reported in malaria vectors, long-lasting insecticidal nets (LNs) still play a key role in controlling malaria transmission. This study tested the efficacy of MiraNet®, a pyrethroid-based LN against a wild population of Anopheles arabiensis in northern Tanzania. DuraNet® was used as a positive control in this evaluation. Standard WHO laboratory bioefficacy evaluations of MiraNet and DuraNet that were unwashed or had been washed 20 times indicated optimal knockdown and mortality for both net types against a susceptible strain of Anopheles gambiae s.s. Standard experimental hut evaluations were conducted to evaluate the efficacy of both nets against a wild population of An. arabiensis. The killing effect of MiraNet was 54.5% for unwashed and 50% for 20 times washed while DuraNet achieved 44.4% mortality for unwashed and 47.4% for 20 times washed against wild An. arabiensis. Both DuraNet and MiraNet exhibited significantly higher killing effects (> 44.4%). There was no significant difference in deterrence or induced exophily detected between the treatment arms for either net. Additionally, there were no adverse effects reported among hut sleepers. The results of this study indicate that the pyrethroid net MiraNet can be used effectively against wild populations of An. gambiae s.l. of low to moderate resistant levels from Northern Tanzania., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study intended to evaluate the larvicidal activity of Feronia limonia leaf essential oil against the wild population of Anopheles arabiensis Patton larvae in laboratory and semi-field environments. Larvae mortality was observed after 12, 24, 48, and 72 hours of exposure. In laboratory condition, the essential oil showed good larvicidal activity against An. arabiensis (LC 50  = 85.61 and LC 95  = 138.03 ppm (after 12 hours); LC 50  = 65.53 and LC 95  = 117.95 ppm (after 24 hours); LC 50  = 32.18 and LC 95  = 84.59 ppm (after 48 hours); LC 50  = 8.03 and LC 95  = 60.45 ppm (after 72 hours), while in semi-field experiments, larvicidal activity was (LC 50  = 91.89 and LC 95  = 134.93 ppm (after 12 hours); LC 50  = 83.34 and LC 95  = 109.81 ppm (after 24 hours); LC 50  = 66.78 and LC 95  = 109.81 (after 28 hours); LC 50  = 47.64 and 90.67 ppm (after 72 hours). These results give an insight on the future use of F. limonia essential oils for mosquitoes control., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2023 Eliningaya J. Kweka et al.)

Mosquitoes' current insecticide resistance status in available public health insecticides is a serious threat to mosquito control initiatives. Microbe-based control agents provide an alternative to conventional pesticides and insecticides, as they can be more targeted than synthetic insecticides. The present study was focused on identifying and investigating the mosquitocidal potential of Cladophialophora bantiana, an endophytic fungus isolated from Opuntia ficus-indica. The Cladophialophora species was identified through phylogenetic analysis of the rDNA sequence. The isolated fungus was first evaluated for its potential to produce metabolites against Aedes aegpti and Culex quinquefasciatus larvae in the 1-4th instar. The secondary metabolites of mycelium extract were assessed at various test doses (100, 200, 300, 400, and 500 μg/mL) in independent bioassays for each instar of selected mosquito larvae. After 48 h of exposure, A. aegypti expressed LC 50 values of 13.069, 18.085, 9.554, and 11.717 μg/mL and LC 90 = 25.702, 30.860, 17.275, and 19.601 μg/mL; followed by C. quinquefasciatus LC 50 = 14.467, 11.766, 5.934, and 7.589 μg/mL, and LC 90 = 29.529, 20.767, 11.192, and 13.296 μg/mL. The mean % of ovicidal bioassay was recorded 120 h after exposure. The hatchability (%) was proportional to mycelia metabolite concentration. The enzymatic level of acetylcholinesterase in fungal mycelial metabolite treated 4th instar larvae indicated a dose-dependent pattern. The GC-MS profile of C. bantiana extracts identified five of the most abundant compounds, namely cyclobutane, trans-3-undecene-1,5-diyne, 1-bromo-2-chloro, propane, 1,2,3-trichloro-2-methyl-, 5,5,10,10-tetrachlorotricyclo, and phenol, which had the killing effect in mosquitoes. Furthermore, the C. bantiana fungus ethyl acetate extracts had a strong larvicidal action on A. aegypti and C. quinquefasciatus. Finally, the toxicity test on zebrafish embryos revealed the induction of malformations only at concentrations above 1 mg/mL. Therefore, our study pioneered evidence that C. bantiana fungal metabolites effectively control A. aegypti and C. qunquefasciastus and show less lethality in zebrafish embryos at concentrations up to 500 μg/mL., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

In Ethiopia, malaria incidence has significantly reduced in the past decade through the combined use of conventional vector control approaches and treatment using antimalarial drugs. However, the sustainability of this achievement is threatened by the shift in biting and resting behaviors and emergence of insecticide resistance by the primary malaria vector. Therefore, continuous monitoring of the behaviour of malaria mosquitoes in different sentinel sites is crucial to design effective prevention and control methods in the local context. Entomological investigations were conducted in three sentinel sites for five consecutive months during the major malaria transmission season. The species composition, population dynamics, biting and resting behaviours of malaria vectors were determined using center for disease control and prevention (CDC) light trap, human landing catch (HLC), pyrethrum spray catch (PSC) and Pitfall shelter collection (PFS). Accordingly, 10 households for CDC, 10 households for PSC, 10 households for PFS and 5 households for HLC from each site were randomly enrolled for mosquito collection. A total of 8,297 anopheline mosquitoes were collected from the three sites, out of which 4,525 (54.5 %) were An. gambiae , s.l. 2,028 (24.4 %) were An. pharoensis , 160 (1.9 %) were An. funestus and the rest 1,584 (19 %) were other anophelines ( An. coustani, An. cinerus and An. tenebrosus ). No significant variation (P = 0.476) was observed between indoor (25.2/trap-night and outdoor collections (20.1/trap-night). Six hundred seventy six (43.3%) of An. gambiae s.l. (primary vector) were collected between 18:00 and 22:00 h. Biting activity declined between 00:00 and 02:00 h. The national malaria control program should pay close attention to the shifting behavior of vector mosquitoes as the observed outdoor feeding tendency of the vector population could pose challenges to the indoor intervention tools IRS and LLINs., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s).)

Background: Rodents are known to be reservoirs of plague bacteria, Yesinia pestis in the sylvatic cycle. A preliminary investigation of the suspected plague outbreak was conducted in Madunga Ward, Babati District Council in Manyara Region December-2019-January 2020 Following reported two cases which were clinically suspected as showing plague disease symptoms., Method: The commensal and field rodents were live trapped using Sherman traps in Madunga Ward, where plague suspect cases were reported and, in the Nou-forest reserve areas at Madunga Ward, Babati District Council, to assess plague risk in the area. Fleas were collected inside the houses using light traps and on the rodents 'body after anaesthetizing the captured rodent to determine flea indices which are used to estimate the risk of plague transmission. Lung impression smears were made from sacrificed rodents to examine for possible bipolar stained Yersinia spp bacilli., Results: A total of 86 rodents consisting of ten rodent species were captured and identified from the study sites. Nine forest rodent species were collected. Field/fallow rodent species were dominated by Mastomys natalensis. whereas domestic rodent species captured was Rattus rattus. Overall lung impression smear showed bipolar stain were 14 (16.28%) while House Flea Index (HFI) was 3.1 and Rodent Flea Index (RFI) was 1.8., Conclusion: The findings of this study have shown that, the presence of bipolar stained bacilli in lung impression smears of captured species of rodents indicates (not confirmed) possible circulation of Yesrsinia pests in rodents and the high flea indices in the area which included the most common flea species known to be plague vectors in Tanzania could have played transmission role in this suspected outbreak. The study recommends surveillance follow-up in the area and subject collected samples to the standard plague confirmatory diagnosis., (Copyright © 2022. Published by Elsevier B.V.)

Background: More than 90% of malaria cases occur in Africa where the disease is transmitted by Anopheles gambiae and Anopheles arabiensis. This study evaluated the anti-mosquito properties of Juniperus virginiana (JVO) and Pelargonium roseum (PRO) essential oils (EOs) against larvae and adults of An. gambiae sensu lato (s.l.) from East Africa in laboratory and semi-field conditions., Methods: EOs was extracted from the aerial green parts of Asian herbs by hydrodistillation. Their constituents were characterized by gas chromatography-mass spectrometry (GC-MS). Larvicidal activities of JVO, PRO, and PRO components [citronellol (CO), linalool (LO), and geraniol (GO)] were investigated against An. gambiae sensu stricto (s.s.). The percentage of knockdown effects and mortality rates of all oils were also evaluated in the adults of susceptible An. gambiae s.s. and permethrin-resistant An. arabiensis., Results: GC-MS analyses identified major constituents of JVO (sabinene, dl-limonene, β-myrcene, bornyl acetate, and terpinen-4-ol) and PRO (citronellol, citronellyl formate, L-menthone, linalool, and geraniol). Oils showed higher larvicidal activity in the laboratory than semi-field trials. The LC 50 values for JVO/PRO were computed as 10.82-2.89/7.13-0.9 ppm and 10.75-9.06/13.63-8.98 ppm in laboratory and semi-field environments, respectively at exposure time of 24-72 h. The percentage of knockdown effects of the oils were also greater in An. gambiae s.s. than in An. arabiensis. Filter papers impregnated with JVO (100 ppm) and PRO (25 ppm) displayed 100% mortality rates for An. gambiae s.s. and 3.75% and 90% mortality rates, for An. arabiensis populations, respectively. Each component of CO, LO, and GO exhibited 98.13%, 97.81%, and 87.5%, respectively, and a mixture of the PRO components indicated 94.69% adult mortality to permethrin-resistant An. arabiensis., Conclusions: The findings of this study show that PRO and its main constituents, compared to JVO, have higher anti-mosquito properties in terms of larvicidal, knockdown, and mortality when applied against susceptible laboratory and resistant wild populations of An. gambiae s.l. Consequently, these oils have the potential for the development of new, efficient, safe, and affordable agents for mosquito control., (© 2022. The Author(s).)

Diet quality is of paramount importance for egg batch size, longevity, and mortality of vector mosquitoes. Oviposition site presence and absence assumed to be dry season means a lot to the survivorship and mortality of most anthropophilic malaria vectors in sub-Saharan Africa. This study has assessed the effect of different diets and oviposition-site deprivation (OSD) on survivorship, longevity, and mortality of An. gambiae s.s. To determine the effect of diet and OSD on mortality, gonotrophic dissociation rates, longevity, and survivorship, six treatments were employed: Blood Fed with Oviposition (BFO), Blood Fed without oviposition (BF), Blood and Sugar Fed with Oviposition (BSFO), Blood and Sugar Fed without oviposition (BSF), Sugar Fed with Oviposition (SFO), and Sugar Fed without oviposition (SF). Mortality and gonotrophic dissociation were monitored daily. This study found that female mosquitoes offered blood meals with sugar solution and oviposition deprivation survived longer than those deprived of oviposition deprivation. Similarly, female mosquitoes fed on blood and provided with oviposition deprivation lived longer than those without oviposition deprivation. The gonotrophic dissociation rates were found to be lower in groups provided with oviposition deprivation. Our results show that OSD has a direct impact on the survivorship, gonotrophic dissociation rate, and longevity of the malaria anthropophilic vector, An. gambiae s.s., regardless of the diet., Competing Interests: The authors declare that they have no conflict of interest., (Copyright © 2022 Paulo S. Chisulumi et al.)

Primaquine is a gametocytocidal drug known to significantly reduce malaria transmission. However, primaquine induces a dose-dependent acute hemolytic anemia (AHA) in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency that has led to a limited use of the drug especially in Africa where the condition is common. The World Health Organization (WHO) now recommends a single low dose (SLD) of primaquine (0.25 mg/kg) as P. falciparum gametocytocidal without the need for prior screening of G6PD status. Adoption and implementation of SLD primaquine in Africa may probably reduce malaria transmission, a pre-requisite for malaria elimination. This review therefore, focused on the safety of primaquine for control of malaria in Africa. The literature search was performed using online database Google Scholar, PubMed, HINARI, and Science Direct. Search terms used were "malaria", "primaquine", "safety", "G6PD deficiency", "large scale" or "mass administration". Clinical trials in many African countries have shown SLD primaquine to be safe especially in a milder African G6PD A- variant. Likewise, large-scale primaquine administrations outside Africa involving hundreds of thousands to tenths of millions of participants and with severe variants of G6PD deficiency have also shown primaquine to be safe and well-tolerated. Fourteen deaths associated with primaquine have been reported globally over the past 6 decades, but none occurred following the administration of SLD primaquine. Available evidence shows that the WHO-recommended SLD primaquine dose added to effective schizonticides is safe and well-tolerated even in individuals with G6PD deficiency, and therefore, it can be safely used in the African population with the mildest G6PD A- variant., (© 2022. The Author(s).)

The present study focused on preparing a nano-ointment base integrated with biogenic gold nanoparticles from Artemisia vulgaris L. leaf extract. As prepared, nano-ointment was characterized by using Fourier-transform infrared spectroscopy, and the morphology of the nano-ointment was confirmed through a scanning electron microscope. Initially, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide results showed nano-ointment cytocompatibility at different concentrations (20-200 μg/mL) against L929 cells. The in vitro hemolysis assay also revealed that the nano-ointment is biocompatible. Further studies confirmed that nano-ointment has repellent activity with various concentrations (12.5, 25, 50, 75, and 100 ppm). At 100 ppm concentration, the highest repellent activity was observed at 60-min protection time against the Aedes aegypti L. female mosquitoes. The results indicated that the increasing concentration of nano-ointment prolongs the protection time. Moreover, the outcome of this study provides an alternative nano-ointment to synthetic repellent and insecticides after successful clinical trials. It could be an eco-friendly, safer nano-bio repellent, which can protect from dengue fever mosquitoes., (© 2021. Sociedade Entomológica do Brasil.)

A field survey was done in teak ( Tectona grandis F.) forests in South India to explore the entomopathogenic effect of Metarhizium anisopliae (Ascomycota: Sordariomycetes) against teak defoliator, Hyblaea puera (Lepidoptera: Hyblaeidae). About 300 soils and infected insect samples were collected during the survey and thirty-six fungal isolates were isolated from soil and insect samples and characterized. The fungi were cultured on PDAY with dodine and antibiotics. Generally, the EPF culture was incubated at 27 °C in darkness for 15 days. Virulence of the Entomopathogenic Fungi (EPF) ability to germinate under cold and heat temperatures was assessed in a culture impregnated with conidia. In the experiment, it was found that for the first time M etarhizium quizhouense , Metarhizium robertsii , and M etarhizium majus species caused significantly higher mortality to hosts. These isolates of M. anisopliae, M. robertsii, M. majus , and M. quizhouense were all considered to be effective virulent and environmentally adaptive. The Metarhizium isolates were recommended as effective bio-control agents through the field investigation of teak defoliator Hyblaea puera from South India forest. This study paves the way to utilize the indigenous isolates of EPF for the control of teak defoliator and to combat the pests thatare resistant to insecticide.

Currently, medical and stored grain pests are major concerns of public health and economies worldwide. The synthetic pesticides cause several side effects to human and non-target organisms. Copper nanoparticles (CuNPs) were synthesized from an aqueous extract of Metarhizium robertsii and screened for insecticidal activity against Anopheles stephensi , Aedes aegypti , Culex quinquefasciatus , Tenebrio molitor and other non-target organisms such as Artemia salina , Artemia nauplii, Eudrilus eugeniae and Eudrilus andrei . The synthesized copper nano-particles were characterized using, UV-vis spectrophotometer, Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Energy Dispersive X-Ray analysis (EDaX), High Resolution Scanning Electron Microscope (HR-SEM) and Atomic Force Microscope (AFM) analysis. Insects were exposed to 25 μg/mL concentration produced significant mortality against larvae of A . stephensi , A . aegypti , C . quinquefasciatus and T . molitor . The lower toxicity was observed on non-target organisms. Results showed that, M . robertsii mediated synthesized CuNPs is highly toxic to targeted pests while they had lower toxicity were observed on non-target organisms.

The success of long-lasting insecticidal nets (LLIN) as the primary method for preventing malaria is threatened by pyrethroid resistance in Anopheles vectors. New generation long-lasting nets incorporating PBO synergist (piperonyl butoxide) with pyrethroid are designed to control insecticide-resistant mosquitoes. The efficacy of Veeralin® PBO LLINs was evaluated in experimental huts against wild free-flying pyrethroid-resistant Anopheles funestus ( s.l. ). Mosquito mortality, blood-feeding inhibition and personal protection were compared between untreated nets, standard LLINs and PBO/pyrethroid combination nets. Blood-feeding rates recorded with 20-times washed Veeralin were not significantly different from those with 20-times washed PermaNet 3.0 LLIN, a WHO Pre-Qualification Team (PQT) approved PBO/pyrethroid LLIN. This provides evidence that Veeralin LLIN provides similar blood-feeding inhibition to the standard approved LLIN and thus meets WHO PQT criteria for blood-feeding. Results show significantly higher mortality for Veeralin PBO LLINs against pyrethroid-resistant Anopheles funestus ( s.l. ) compared to DuraNet, a WHO PQT approved standard pyrethroid-only LLIN, both when unwashed and washed 20 times. The improved efficacy over a standard pyrethroid-only LLIN can be attributed to the effect of PBO in the Veeralin LLIN, hence meeting the Vector Control Advisory Group (VCAG) criteria for a resistance breaking LLIN., (© 2021 The Author(s).)

Background: Mosquitoes biolarvicides remain the most important method for mosquito control. The previous studies have shown Aspergillus sp. -expressed larvicidal properties against mosquito species. The present study evaluated larvicidal and histopathological effect of an endophytic fungus Aspergillus tamarii isolated from theCactus stem ( Opuntia ficus-indica Mill) ., Method: The molecular identification of isolated A. tamarii was done by PCR amplification (5.8s rDNA) using a universal primer (ITS-1 and ITS-2). The secondary metabolites of A. tamarii was tested for larvicidal activity against Aedes aegypti and Culex quinquefasciatus . Larvicidal bioassay of different concentrations (- 100, 300, 500, 800 and 1000 μg/mL) isolated extracts were done according to the modified protocol. Each test included a set of control groups (i.e. DMSO and distilled water). The lethal concentrations (LC 50 and LC 90 ) were calculated by probit analysis. Experimental monitoring duration was 48 h., Results: The ethyl acetate extract from A. tamarii fungus resulted - excellent mosquitocidal effect against Ae. aegypti and Cx. quinquefasciatus mosquitoes, with least LC 50 and LC 90 values. -After 48 h, the Ae. aegypti expressed better results (LC 50 = 29.10, 18.69, 16.76, 36.78 μg/mL and the LC 90 = 45.59, 27.66, 27.50, 54.00 μg/mL) followed by Cx. quinquefaciatus (LC 50 = 3.23, 24.99, 11.24, 10.95 μg/mL and the LC 90 = 8.37, 8.29, 21.36, 20.28 μg/mL). The biochemical level of A. tamarii mycelium extract on both larvae was measured and the results shown a dose dependent activity on the level of AchE, α- and β-carboxylesterase assay. Gas Chromatography and Mass Spectroscopy (GC-MS) profile of A. tamarii extract reflected three compounds i.e. preg-4-en-3-one, 17. α-hydroxy-17. β-cyano- (7.39%), trans-3-undecene-1,5-diyne (45.77%) and pentane, 1,1,1,5-tetrachloro- (32.16%) which which might had attributed to larvae mortality., Conclusion: The findings of - present study shows that the use of endophytic A. tamarii fungal metabolites for control of dengue and filariasis vectors is promising and needs a semifield and small scale filed trials., (© 2020 The Author(s).)

Background: Insecticide resistance among the vector population is the main threat to existing control tools available. The current vector control management options rely on applications of recommended public health insecticides, mainly pyrethroids through long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). Regular monitoring of insecticide resistance does not provide information on important factors that affect parasite transmission. Such factors include vector longevity, vector competence, feeding success, and fecundity. This study investigated the impacts of insecticide resistance on longevity, feeding behaviour, and egg batch size of Anopheles gambiae s.l., Method: The larval sampling was conducted in rice fields using a standard dipper (350 ml) and reared to adults in field insectary. A WHO susceptibility test was conducted using standard treated permethrin (0.75%) and deltamethrin (0.05%) papers. The susceptible Kisumu strain was used for reference. Feeding succession and egg batch size were monitored for all survivors and control., Results: The results revealed that mortality rates declined by 52.5 and 59.5% for permethrin and deltamethrin, respectively. The mortality rate for the Kisumu susceptible strain was 100%. The survival rates of wild An. gambiae s.l. was between 24 and 27 days. However, the Kisumu susceptible strain blood meal feeding was significantly higher than resistant colony ( t  = 2.789, df = 21, P =0.011). Additionally, the susceptible An. gambiae s.s. laid more eggs than the resistant An.gambiae s.l. colony (Χ 2  = 1366, df = 1, P ≤ 0.05)., Conclusion: It can, therefore, be concluded that the wild An. gambiae s.l. had increased longevity, blood feeding, and small egg batch size compared to Kisumu susceptible colonies., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2020 Grace Msangi et al.)

Background: Surveillance of the clinical morbidity of malaria remains key for disease monitoring for subsequent development of appropriate interventions. This case study presents the current status of malaria morbidities following a second round of mass distribution of long-lasting insecticidal nets (LLINs) on Ukerewe Island, northwestern Tanzania., Methods: A retrospective review of health-facility registers to determine causes of inpatient morbidities for every admitted child aged <5 years was conducted to ascertain the contribution of malaria before and after distribution of LLINs. This review was conducted from August 2016 to July 2018 in three selected health facilities. To determine the trend of malaria admissions in the selected facilities, additional retrospective collection of all malaria and other causes of admission was conducted for both <5- and >5-year-old patients from July 2014 to June 2018. For comparison purposes, monthly admissions of malaria and other causes from all health facilities in the district were also collected. Moreover, an LLIN-coverage study was conducted among randomly selected households (n=684)., Results: Between August 2016 and July 2018, malaria was the leading cause of inpatient morbidity, accounting for 44.1% and 20.3% among patients <5 and >5 years old, respectively. Between October 2017 and January 2018, the mean number of admissions of patients aged <5 years increased 2.7-fold at one health center and 1.02-fold for all admissions in the district. Additionally, approximately half the households in the study area had poor of LLIN coverage 1 year after mass distribution., Conclusion: This trend analysis of inpatient morbidities among children aged <5 years revealed an upsurge in malaria admissions in some health facilities in the district, despite LLIN intervention. This suggests the occurrence of an unnoticed outbreak of malaria admissions in all health facilities., Competing Interests: All authors declare that they have no competing interests in this work., (© 2020 Kapesa et al.)

Background: The fungal toxin acts as effective, low-cost chemical substances for pest control worldwide and also an alternative to synthetic insecticides. This study assessed the larvicidal potential of Metarhizium anisopliae fungi derived metabolites against Aedes aegypti, Anopheles stephensi, Culex quinquefasciatus and non-targeted organisms at 24hr post treatment., Method: Isolation of entomopathogenic fungi M. anisopliae from natural traps confirmed by using 18s rDNA biotechnological tools. Crude extracts from M. anisopliae solvent extraction and their secondary metabolites were bio-assayed following WHO standard procedures against Ae. aegypti, An. stephensi and Cx. quinquefasciatus, Artemia nauplii, Eudrilus eugeniae, and Solanum lycopersicum after 24 hr exposure. Histopathological analysis of E. eugeniae treated with fungi metabolites toxicity compared to those treated with Monocrotophos after 24hrpost-treatment. M. anisopliae metabolites were characterized using GC-MS and FT-IR analysis., Results: The larvicidal activity was recorded in highest concentration of 75μg/ml, with 85%, 97% and 89% mortality in Ae. aegypti, An. stephensi and Cx. quinquefasciatus respectively. M. anisopliae metabolites produced LC50 values in Ae. aegypti, 59.83μg/ml, in An. stephensi, 50.16μg/ml and in Cx. quinquefasciatus, 51.15μg/ml respectively. M. anisopliae metabolites produced lower toxic effects on A. nauplii, LC50 values were, 54.96μg/ml respectively. Bio-indicator toxicity results show 18% and 58% mortality was recorded in E. eugeniae and A. nauplii and also there is no phytotoxicity that was observed on S. lycopersicum L. under semi-field condition. E. eugeniae histopathological studies shows fungal metabolites showed lower sub-lethal effects compared to synthetic chemical pesticide at 24hrs of the treatment. The GC-MS and FT-IR analysis identified five major components of active ingredients., Conclusion: Findings of this study indicate that, M. anisopliae ethyl acetate derived secondary metabolites are effective against larvae of Ae. aegypti, An. stephensi and Cx. quinquefasciatus mosquito species, lower toxicity effects were observed on non-target organisms such as, Artemia nauplii, Eudrilus eugeniae as well as, no toxicity effect were observed on Solanum lycopersicum. Further research should be conducted in laboratory for separation of single pure molecule and be tested semifield conditions., Competing Interests: Authors declare that they do not have any conflict of interest.

The scaling-up of malaria control interventions in northern Tanzania has resulted in a decline in malaria prevalence and vector species composition. Despite this achievement, residual malaria transmission remains a concern in the area. The main aim of this study was to investigate malaria vector species composition, parasite infectivity rates, and the presence of insecticide knockdown resistance (kdr) mutations in three sites that have experienced a significant decline in malaria in northern Tanzania. Adult mosquitoes were sampled using light traps in houses and hand-aspirators in cowsheds, whereas the standard dipping method was used for sampling mosquito larvae. Adult mosquitoes identified as Anopheles gambiae s.l. and An. funestus s.l. and larval stages III and IV of An. gambiae s.l. were stored in absolute ethanol for further laboratory molecular identification. The identified species in the An. gambiae complex were An. gambiae s.s., An. merus, An. quadriannulatus, and An. arabiensis, whereas the An. funestus group comprised An. funestus s.s., An. rivulorum, and An. leesoni. For An. gambiae s.s. analyzed from Zeneth, 47.6% were kdr-East homozygous susceptible, 35.7% kdr-East heterozygous resistant, 9.6% kdr-East homozygous resistant, and 7.1% undefined, whereas specimens from Kwakibuyu were 45.5% kdr-East homozygous susceptible, 32.7% kdr-East heterozygous resistant, 16.3% kdr-East homozygous resistant, and 5.5% undefined. There were no kdr-West alleles identified from any specimen. The overall malaria parasite infectivity rate was 0.75%. No infections were found in Moshi. The findings indicate that populations of the major malaria vector mosquitoes are still present in the study area, with An. funestus taking a lead in malaria transmission., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Cimex hemipterus resistance to residual insecticides is a growing public health concern worldwide. Herein, we report the susceptibility status of C. hemipterus against pyrethroid (permethrin) and organophosphate (dichlorvos) insecticides in Dar es Salaam. The knockdown efficacy of dichlorvos (99%) was greater than that of permethrin (43%), and mortality at the end of 24 h was also greater for dichlorvos than for permethrin. Mortality in recommended concentration of permethrin was lower than manufacturer's expectations. In contrast, similar concentrations in dichlorvos resulted into mortality of 100% at the end of 24 h. LC50 and LC95 values for permethrin were 3.36 (2.356-4.364) and 2,887.39 (2,886.37-2,888.39), respectively, whereas those of dichlorvos were 7.91 (3.85-11.97) and 44.39 (40.33-48.45). Dar es Salaam city has high coverage and usage of long-lasting insecticidal nets (LLINs) for prevent malaria. The resistance in bedbugs to permethrin may be related to the widespread use of the insecticide in LLINs. We recommend of the change from pyrethroids dichlorvos for the control of bedbugs., (© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: The decline in malaria cases and vectors is major milestone in fighting against malaria. The efficacy of MAGNet long-lasting insecticidal nets (MAGNet LLIN), an alpha-cypermethrin incorporated long-lasting net, with the target dose ± 25% of 5.8 g active ingredient (AI)/kg (4.35-7.25 g AI/kg) was evaluated in six veranda-trap experimental huts in Muheza, Tanzania against freely flying wild population of Anopheles funestus., Methods: MAGNet LLINs were tested against wild, free-flying, host-seeking An. funestus mosquitoes over a period of 6 weeks (total of 36 nights in the huts). MAGNet LLIN efficacy was determined in terms of mosquito mortality, blood-feeding inhibition, deterrence, induced exiting, personal protection, and insecticidal killing over 20 washes according to WHO standardized procedures. Efficacy was compared with reference to a WHOPES recommended approved LLINs (DuraNet) and to a net conventionally treated (CTN) treated with alpha-cypermethrin at WHO-recommended dose and washed to just before cut-off point. The efficacy of MAGNet was evaluated in experimental huts against wild, free-flying, pyrethroid-resistant An. funestus. The WHO-susceptibility method was used to detect resistance in wild Anopheles exposed to 0.75% permethrin. Mosquito mortality, blood-feeding inhibition and personal protection were compared between untreated nets and standard LLINs. Blood-feeding rates were recorded and compared between the 20 times washed; blood-feeding rates between 20 times washed MAGNet LLIN and 20 times washed WHOPES-approved piperonyl butoxide (PBO)/pyrethroid were not statistically different (p > 0.05)., Results: The results have evidently shown that MAGNet LLIN provides similar blood-feeding inhibition, exophily, mortality, and deterrence to the standard approved LLIN, thus meeting the WHOPES criteria for blood feeding. The significantly high feeding inhibition and personal protection over pyrethroid-resistant An. funestus recorded by both unwashed and 20 times washed MAGNet compared to the unwashed DuraNet, the WHOPES-approved standard pyrethroid-only LLIN provides proof of MAGNet meeting Phase II WHOPES criteria for a LLIN., Conclusion: Based on this study, MAGNet has been shown to have a promising impact on protection when 20 times washed against a highly resistant population of An. funestus.

Several trials and reviews have outlined the potential role of larviciding for malaria control in sub-Saharan Africa (SSA) to supplement the core indoor insecticide-based interventions. It has been argued that widespread use of long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) interventions in many parts of Africa result in many new areas with low and focal malaria transmission that can be targeted with larvicides. As some countries in SSA are making good progress in malaria control, larval source management, particularly with bacterial larvicides, could be included in the list of viable options to maintain the gains achieved while paving the way to malaria elimination. We conducted a review of published literature that investigated the application of bacterial larvicides, Bacillus thuringiensis var. israelensis (Bti) and/or Bacillus sphaericus (Bs) for malaria vector control in SSA. Data for the review were identified through PubMed, the extensive files of the authors and reference lists of relevant articles retrieved. A total of 56 relevant studies were identified and included in the review. The findings indicated that, at low application rates, bacterial larvicide products based on Bti and/or Bs were effective in controlling malaria vectors. The larvicide interventions were found to be feasible, accepted by the general community, safe to the non-target organisms and the costs compared fairly well with those of other vector control measures practiced in SSA. Our review suggests that larviciding should gain more ground as a tool for integrated malaria vector control due to the decline in malaria which creates more appropriate conditions for the intervention and to the recognition of limitations of insecticide-based vector control tools. The advancement of new technology for mapping landscapes and environments could moreover facilitate identification and targeting of the numerous larval habitats preferred by the African malaria vectors. To build sustainable anti-larval measures in SSA, there is a great need to build capacity in relevant specialties and develop organizational structures for governance and management of larval source management programmes.

Background: The wide distribution of malaria mosquito breeding sites within tropical environments limits the mosquito larval source management efforts to control malaria. Rice farming contributes substantially in supporting malaria mosquito productivity in tropical countries. To overcome this challenge, this study was carried out to determine the effect of applying a mixture of biolarvicide and fertilizer on mosquito larvae density in rice farms under semi-field conditions in Tanzania., Methods: A semi-field experiment was designed to determine the timing of application of a biolarvicide, Bacillus thuringiensis israelensis (Bti) and fertilizer (di-ammonium phosphate-DAP or urea) and assess their effect on mosquito larvae density and rice grain outputs. The experiment had five blocks (4 treatment arms and one control arm) and each had four replicates. Treatment arms had different intervals of days between treatments for mixtures of fertilizer and biolarvicides. The dosages used were 10 g of Bti/16 M 2 and 160 g of DAP/Urea/16 m 2 ., Results: In overall, the intervention blocks (with biolarvicide) had lowest mean mosquito larvae abundance compared to control block (F = 22.42, P < 0.001). Similarly, the control arm maintained highest density of Anopheles gambiae sensu lato larvae compared to interventions blocks (F = 21.6, P < 0.001). The best determined timing for application of Bti was in 7 and in 10 days (F = 3.753, P < 0.001). There was neither significant different in mean rice grain harvest per ten panicle (F = 1.453, P = 0.27) nor mean difference in rice grain harvest (F = 1.479, P = 0.26) per intervention arms., Conclusion: The findings of this study have shown that application of a mixture of Bti and fertilizer have impact on both mosquito larvae density and maintaining yield rice harvest. Thus, application of a combination of biolarvicide and fertilizer can be an alternative approach in malaria mosquito intervention among rice farming communities of rural Tanzania.

Background: The use of larval source management as a supplementary intervention for malaria control has not been widely used in rural Africa due to perceived high costs and complex logistics. To reduce the cost of larviciding in rice farming communities, concurrent application of biolarvicides and fertilizer in rice fields was introduced to control malaria vectors larvae and improve rice grain yields. The present study determined rice farmers' perceptions and acceptability in the use of a combination of biolarvicide and fertilizers in farming practices., Methods: This was a qualitative study conducted among rice farmers at Kilangali village, south-central Tanzania. Semi-structured interviews and three focus group discussions (FGDs) were conducted with men and women who participated in the biolarvicide and fertilizer application project. The interviews and discussion focused on knowledge, attitudes and perceptions of participants on the use of the innovation in their farming practices and their willingness to pay for the innovation., Results: A total of 40 (mean age = 38.8 ± 10.12 years) rice farmers were involved in the study. Overall, all farmers agreed that it was possible to apply the two products concurrently with minimal challenges. The trust on the safety of biolarvicides on both human and paddy health was high. Respondents reported no challenge in preparation and applying the product in their rice fields. Over half (56.6%) of the participants reported an average decrease in mosquito density in their households and a quarter (26.6%) of them reported a decrease in mosquito population in their farms. Similarly, 93.3% of the participants reported that the intervention had reduced malaria risk in their households. In general, all participants expressed willingness to contribute to a biolarvicide and fertilizer programme and to use the approach in their farming practices., Conclusion: Community-based concurrent application of biolarvicides and fertilizer in rice fields was feasible and led to a perceived reduction in mosquito density. Willingness to pay for the larviciding/fertilizer approach was expressed by participants and they accepted to use the approach in their future farming practices. However, the impact of this approach on malaria transmission and rice grain harvest need to be evaluated in a large-scale programme.

Background: Mass rearing requires a large colony from which male individuals can be harvested for sterilization and release. Attention is needed when monitoring life parameters of the reared population, knowing that any variations within the target population would lead to mismatching between two populations. The aim of this study was to assess the impact of Anopheles gambiae sensu stricto (s.s.) egg storage on hatchability and life history traits. For each parameter, comparison was made between freshly laid and stored eggs in three densities (40, 80, 120 eggs)., Methods: Anopheles gambiae s.s. freshly laid eggs were collected from the Tropical Pesticide Research Institute (TPRI) insectary. Eggs to be stored were kept at - 20 °C for 10 min and then transferred to refrigerators at 4 °C for intervals of 5, 10, 15, 20, and 25 days. After respective storage days, the eggs were transferred from refrigerators to ambient temperature of (25 ± 2) °C for 24 h and then placed in incubators for 24 h. Thereafter eggs were hatched. The egg hatchability, emerged larvae development, larvae survival and emerged adult sex ratios were monitored., Results: This study found that hatching rates decreased with increase in storage time. The difference was significant in eggs stored for 10 and 15 days (P < 0.05). There were no significant differences in hatching rates between An. gambiae eggs stored for 5 days and freshly hatched eggs (P > 0.05). Anopheles larvae development (L1 to pupae) was not significantly affected by storage time across all hatching densities. The study also found that larvae survival decreased with increase in egg storage time. However, there was no significant difference between larvae from freshly hatched eggs and those from eggs at 5 and 10 storage days (P > 0.05) but not for eggs stored for 15 days. Furthermore, there was a decrease in emerged adult males and increase in females relative to increased time of egg storage. The difference was significant (P < 0.05) at 15 storage days but not for eggs stored for 5 and 10 days (in triplicate densities)., Conclusion: From this study it was concluded that storing An. gambiae eggs at 4 °C and 48 ± 2% relative humidity (RH) for 5 days is the optimal condition and time that did not affect egg hatching rates, larval development and survivorship and emerged adult mosquito sex ratio.

Background: Mosquitoes have developed resistance to multiple classes of insecticides for malaria vector control. A new generation of long-lasting insecticidal bed nets (LLINs) has been developed with increased efficacy against these resistant mosquitoes. The present study therefore evaluated the efficacy of the pyrethroid-based LLINs, DuraNet versus PermaNet 3.0, in an Eastern Africa hut design in Magugu in northern Tanzania where mosquitoes' population higher proportion (69.3%) has been identified as Anopheles gambiae s.l., Methods: Standard World Health Organization bioefficacy evaluations were conducted in both laboratory and experimental huts. Experimental hut evaluations were conducted in an area with high populations of Anopheles arabiensis . All nets used were subjected to laboratory cone bioassays and then to experimental hut trials. Mosquito mortality, blood-feeding inhibition, and personal protection rate were compared between untreated nets, unwashed LN, and LN that were washed 20 times., Results: Standard WHO laboratory bioefficacy evaluations of DuraNet and PermaNet® 3.0 which were untreated, washed, or 20 times washed showed optimal knockdown and mortality for both net types against a susceptible strain of An. arabiensis . In standard experimental hut evaluations, the blood feeding inhibition for PermaNet® 3.0 unwashed and washed was 82.4% (76.3-88.6%) to 91.5% (84.1-98.8%) while for DuraNet was 98.3% (97.0-99.5%) to 96.0% (94.1-88.2%) respectively. The DuraNet LLINs showed a significantly higher killing effect than the other treatment of 90.0% (86.1-94.2%) and 94.0% (90.2-97.9%) for unwashed and washed nets respectively. No significant difference in deterrence or induced exophily was detected between the treatment arms. There were no adverse effects reported among sleepers in the experimental huts., Conclusion: The findings of this study indicate that the pyrethroid-based net DuraNet LLINs attained required efficacy when evaluated against wild population of An. arabiensis from Northern Tanzania. This adds value to the existing vector control tool box which gives community wider choice for vector control., Competing Interests: The hut sleepers who slept in each individual hut under net per night were recruited among the inhabitants of the villages close to the site. The sleepers have been working in huts for the past 7 years and were offered chemoprophylaxis during and for 1 month after the experimental hut trial. They were also informed on the objective of this study and signed an informed consent. This study had experimental permit No.1714 issued by Registrar of Pesticides in Tanzania.Not Applicable.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Background: Passive surveillance of malaria in health facilities remains vital for implementation of control and elimination programs. It is therefore essential understanding current age profile of clinical malaria morbidity, mortality and presentations in areas with variant infection susceptibility. This study aimed at understanding the current malaria morbidity and mortality in Western Kenya., Methods: Surveillance of clinical and asymptomatic parasitological positivity rates of all malaria suspected patients and school children were respectively determined from June 2015 to August 2016. From 2014 to 2016, register books in hospitals were referred and the confirmed malaria cases in conjunction with total number of monthly outpatient visits (OPD) counted. All registered malaria admissions were counted together with other causes of admissions. Moreover, outcome of malaria admissions in terms of discharge or death was recorded using inpatient charts within the same time frame. Prospective surveillance of severe malaria collected information on clinical features of the disease. Giemsa stained blood slides confirmed existence of malaria parasitemia. Chi-square and analysis of variance tests were used, respectively, to compute proportions and means; then a comparison was made between different age groups, periods, and study areas., Results: During the survey of asymptomatic infections among school children, overall blood slide positivity ranged from 6.4% at the epidemic prone site to 38.3% at the hyperendemic site. During the clinical malaria survey, school age children (5-14) presented with overall the highest (45%) blood slide positivity rate among those suspected to have the infection at the epidemic prone study site. The survey of all malaria confirmed and registered cases at OPD found 17% to 27% of all consultations among <5 children and 9.9% to 20.7% of all OPD visits among the ≥5 patients were due to malaria. Moreover, survey of all registered causes of admission in hospitals found 47% of admissions were due to malaria. The disease was a major cause of admission in epidemic prone setting where 63.4% of the <5 children and 62.8% of the ≥5 patients were admitted due to malaria (p>0.05) and 40% of all malaria admissions were school age children. Malaria related death rate was highest among <5 years at the hyperendemic site, that is 60.9 death per 1000 malaria <5 admissions. Conversely, the epidemic prone setting experienced highest malaria related death among ≥15 years (18.6 death per 1000 admissions) than the < 15 years (5.7 death per 1000 admissions of the <15 years) (p< 0.001). Surveillance of severe form of the disease found that hyperpyrexia, hyperparastemia, prostration and convulsions as common presentations of severe disease., Conclusion: Malaria is still the major cause of hospital consultations in Western Kenya with an alarming number of severe forms of the disease among the school aged children at the epidemic prone setting. Mortalities were higher among <5 children years in high infection transmission setting and among ≥15 years in low and moderate transmission settings. Surveillance of asymptomatic and symptomatic malaria along with evaluation of current interventions in different age groups should be implemented in Kenya., Competing Interests: The authors have declared that no competing interests exists.

Background: Malaria continued to be the major public health concern in sub-Sahara Africa, thus for better planning of control activities, periodic surveillance of both clinical and asymptomatic cases remains important. However, the usability of routinely collected malaria data in Kenyan hospitals as a predictor of the asymptomatic malaria infection in the community amidst rapid infection resurgence or reduction in different areas of disease endemicities remains widely unstudied. This study was therefore aimed to evaluate the utility of passive surveillance of malaria in health facilities as a proxy of infection transmission of the surrounding community in different transmission intensities., Methods: Prospective multiple cross-sectional surveys were done in three villages in western Kenya. Monthly asymptomatic malaria positivity among school children, number of outpatient (OPD) confirmed malaria cases and abundancy of indoor resting malaria vectors were surveyed from June 2015 to August 2016. Community surveys on antimalarial drug use among adults and children were also done. Detection of malaria parasitaemia was done using thick and thin Giemsa stained blood slide microscopy for both clinical and school participants. A questionnaire was used to collect information on self-use of antimalarial drugs from randomly selected households., Results: The overall OPD blood slide positivity from all study sites was 26.6% (95%CI 26.2-27.0) and highest being among the 5-14 years (41.2% (95% CI 40.1-42.3). Asymptomatic malaria positivity among the school children were 6.4% (95%CI 5.3-7.5) and 38.3% (95%CI 36.1-40.5) in low and high transmission settings respectively. A strong correlation between overall monthly OPD positivity and the school age children positivity was evident at Marani (low transmission) (rho = 0.78, p  = 0.001) and at Iguhu (Moderate transmission) (rho = 0.61, p  = 0.02). The high transmission setting (Kombewa) showed no significant correlation (rho = - 0.039, p  = 0.89)., Conclusion: Hospital malaria data from low and moderate malaria transmission predicted the infection transmission dynamics of the surrounding community. In endemic sites, hospital based passive surveillance didn't predict the asymptomatic infection dynamics in the respective community., Competing Interests: The study was approved by the Ethical Review board of Kenya Medical Research Institute (SSC protocol No.3005) and received authorization from local health and education authorities. An informed consent was sought from participants before they were involved in the study. School children assented for study participation and the form was countersigned by their parents before they were allowed to participate in the study.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

The microbial larvicides Bacillus thuringiensis var. israelensis and Bacillus sphaericus have been used extensively for mosquito control and have been found to be effective and safe to non-target organisms cohabiting with mosquito larvae. Recently developed long lasting microbial larvicides (LLML), although evading the previous challenge of short duration of activity, increase the risk of persistence of toxins in the treated larval habitats. This study monitored the impact of LLML FourStar ® and LL3 on non-target organisms cohabiting with mosquito larvae in an operational study to control malaria vectors in western Kenya highlands. A total of 300 larval habitats were selected in three highland villages. The habitats were first monitored for 5 weeks to collect baseline data on non-target organisms cohabiting with mosquito larvae and then randomized into two treatment arms (respective FourStar ® and LL3) and one control arm. Non-target organisms were sampled weekly for 5 months after treatment to assess the impact of LLML intervention. Before treatment, the mean density of all non-target organisms combined in the control, LL3 and FourStar ® treated habitats was 1.42, 1.39 and 1.49 individuals per habitat per sampling occasion, respectively. Following treatment, this density remained fairly unchanged for 21 weeks at which time it was 1.82, 2.11, and 2.05 for the respective control, LL3 and FourStar ® treated habitats. Statistical analysis revealed that LL3 and FourStar ® did not significantly alter abundance, richness or diversity of the 11 taxa studied, when comparing the intervention and control larval habitats. However, both FourStar ® and LL3 significantly reduced the density of malaria vectors. In conclusion, one round of label rate application of FourStar ® or LL3 in natural larval habitats did not alter richness, abundance or diversity of the monitored aquatic non-target organisms cohabiting with mosquito larvae to an ecologically significant level.

Background: Malaria vector control efforts have taken malaria related cases down to appreciable number per annum after large scale of intervention tools. Insecticides-based tools remain the major control option for malaria vectors in Kenya and, therefore, the potential of such programs to be compromised by the reported insecticide resistance is of major concern. The objective of this study was to evaluate the status of insecticide resistance in malaria vectors in different agro ecosystems from western Kenya., Methods: The study was carried out in the lowlands and highlands of western Kenya namely; Ahero, Kisian, Chulaimbo, Emutete, Emakakha, Iguhu, and Kabula. World Health Organization tube bioassays was conducted using standard diagnostic dosages of Lambdacyhalothrin, Deltamethrin, Permethrin, DDT, Bendiocarb, and Malathion tested on Anopheles mosquitoes collected from seven sites; Ahero, Kisian, Chulaimbo, Emutete, Emakakha, Iguhu, and Kabula. Biochemical assays, where the enzymatic activity of three enzymes (monooxygenases, esterases, and glutathione S -transferases) were performed on susceptible and resistant mosquito populations. Wild mosquito populations were identified to species level using polymerase chain reaction (PCR). The species of the wild mosquito populations were identified to species level using PCR. Real-time PCR was performed on the susceptible and resistant mosquitoes after the WHO tube bioassays to determine the presence of knockdown resistance ( kdr ) allele., Results: WHO susceptibility tests indicated that Anopheles gambiae showed resistance to Pyrethroids and DDT in all the study sites, to Bendiocarb in Iguhu and Kabula and susceptible to Malathion (100% mortality) in all the study sites. There was an elevation of monooxygenases and esterases enzymatic activities in resistant An. gambiae mosquito populations exposed to Lambdacyhalothrin, Permethrin, Deltamethrin and DDT but no elevation in glutathione S -transferases. A high frequency of L1014S allele was detected in An. gambiae s.s. population, but there was no kdr allele found in Anopheles arabiensis mosquitoes., Conclusion: An. gambiae mosquitoes from western Kenya have developed phenotypic resistance to pyrethroids and DDT. Therefore, there is a need for further research covering different climatic zones with different agroeconomic activities for detailed report on current status of insecticide resistance in malaria vectors.

A hydrolysis probe analysis (TaqMan assay) was used to study clade types in Anopheles funestus sensu stricto Giles, a major malaria vector in sub-Saharan Africa, with specimens collected from Muheza in Tanga, northeastern Tanzania. A total of 186 An. funestus specimens were analysed, revealing that 176 (94.6%) were of clade I and 10 (5.4%) of clade II. These findings extend the distribution of clade type II from southern Mozambique and northern Zambia to northeastern Tanzania. The technique used can also be of great value in assessing the role and contribution of these clade types in malaria transmission and insecticide resistance frequencies for An. funestus s.s., (© 2017 The Royal Entomological Society.)

Background: In sub-Saharan Africa, malaria interventions over the last decades have been successful in reducing both mortality and morbidity. In western Kenya however some areas experience contrasting outcomes of the ongoing interventions while the causes for this observation remains not yet clearly known., Methods: The WHO insecticide (deltamethrin) susceptibility test of the common malaria vectors was studied. Multiple surveys on household use and hospital prescriptions of antimalarial drugs from 2003 to 2015 were done. Along with this, cross sectional surveys on their availability in the local drug dispensing outlets were also done in 2015. Monthly precipitations and air temperature data was collected along with systematic review on abundance and composition of common malaria vectors in the study area before and during interventions. The above factors were used to explain the possible causes of contrasting outcome of malaria interventions between the three study sites., Results: Areas with malaria resurgence or sustained high transmission (Kombewa and Marani) showed higher composition of Anopheles funestus sensu lato (s.l.) than the previously abundant Anopheles gambiae sensu stricto (s.s.) and the later had higher composition to an area with a sustained infection decline (Iguhu). Anopheles gambiae s.l. from Kombewa showed highest resistance (50% mortality) upon exposure to WHO deltamethrin discriminating dosage of 0.75% while those from Marani and Iguhu had reduced resistance status (both had a mean mortality of 91%). Sampled An. funestus s.l. from Marani were also highly resistant to deltamethrin as 57% of the exposed vectors survived. An increasing of mean air temperature by 2 °C was noted for Marani and Iguhu from 2013 to 2015 and was accompanied by an increased rainfall at Marani. Community drug use and availability in selling outlets along with prescription in hospitals were not linked to the struggling control of the disease., Conclusions: The malaria vector species composition shift, insecticide resistance and climatic warming were the likely cause of the contrasting outcome of malaria intervention in western Kenya. Surveillance of malaria parasite and vector dynamics along with insecticide resistance and vector biting behaviour monitoring are highly recommended in these areas.

Background: Insecticide resistance is the major emerging challenge facing the malaria vector control programmes in Tanzania. Proper monitoring and detection is of paramount importance guiding the vector control programmes. This paper presents the effect of mosquito aging on insecticide resistance status in Anopheles arabiensis populations in dry and rainy seasons in northern Tanzania., Methods: Anopheles gambiae s.l. larvae were sampled from rice fields in both dry and rainy seasons and reared in the insectary to adults. The emerged females in batches of 2, 3, 5, and 10 days old were exposed to six insecticides (deltamethrin, permethrin, lambda-cyhalothrin, DDT, bendiocarb and pirimiphos-methyl) to see the effects of age on insecticide resistance. Mosquitoes were exposed to insecticides using WHO standard susceptibility test kits. Knockdown was recorded during the 1-h exposure, while mortality and resistance ratio were recorded 24 h later. Mosquito specimens were identified to species level using the polymerase chain reaction (PCR) method., Results: Among the 326 specimens processed by PCR, 323 (99.1%) were identified as Anopheles arabiensis. There was reduced mortality (ranging from 61 to 97.7%) when adults reared from larvae were exposed to all pyrethroids and bendiocarb in both dry and rainy seasons, while they were fully susceptible to DDT and pirimiphos-methyl. There was a significant increase in mortality rate with increase in mosquito's age in both dry and rainy seasons following exposure to pyrethroids (DF = 1, P < 0.05). Mosquitoes showed significantly higher mortality rates in the rainy season than in the dry season after being exposed to pyrethroids (DF = 1, P < 0.05). Higher mortality rates (94.0-99.8%) were observed in all ages and seasons when mosquitoes were exposed to bendiocarb compared with pyrethroids. Pirimiphos-methyl was only tested in the rainy season so no comparison with dry season mosquitoes could be made., Conclusions: Results showed that An. arabiensis were resistant to pyrethroids in both seasons and that the young age groups exhibited higher levels of resistance compared with the older age groups. Mosquitoes were full susceptible to DDT and pirimiphos-methyl irrespective of the season and age.

Background: Mosquitoes are well-known vectors of many diseases including malaria and lymphatic filariasis. Uses of synthetic insecticides are associated with high toxicity, resistance, environmental pollution and limited alternative, effective synthetic insecticides. This study was undertaken to evaluate the larvicidal efficacy of clove and cinnamon essential oils against laboratory Anopheles gambiae (sensu stricto) and wild An. arabiensis larvae., Methods: The standard WHO guideline for larvicides evaluation was used, and the GC-MS machine was used for active compounds percentage composition analysis and structures identification. Probit regression analysis was used for LC 50 and LC 95 calculations while a t-test was used to test for significant differences between laboratory-reared and wild larvae populations in each concentration of plant extract., Results: Mortality effect of clove and cinnamon essential oils against wild and laboratory-reared larvae had variations indicated by their LC 50 and LC 95 values. The mortality at different concentrations of cinnamon and clove post-exposure for wild and laboratory-reared larvae were dosage-dependent and were higher for cinnamon than for clove essential oils. The mortality effect following exposure to a blend of the two essential oils was higher for blends containing a greater proportion of cinnamon oil. In the chemical analysis of the active ingredients of cinnamon essential oil, the main chemical content was Eugenol, and the rarest was β-Linalool while for clove essential oil, the main chemical content was Eugenol and the rarest was Bicyclo., Conclusion: The essential oils showed a larvicidal effect which was concentration-dependent for both laboratory and wild collected larvae. The active ingredient compositions triggered different responses in mortality. Further research in small-scale should be conducted with concentrated extracted compounds.

Background: Evidence of insecticide resistance has been documented in different malaria endemic areas. Surveillance studies to allow prompt investigation of associated factors to enable effective insecticide resistance management are needed. The objective of this study was to assess insecticide use pattern and phenotypic susceptibility level of Anopheles gambiae sensu lato to insecticides commonly used in malaria control in Moshi, northern Tanzania., Methods: A cross-sectional survey was conducted to assess insecticide usage pattern. Data was collected was through closed and open ended questionnaires The WHO diagnostic standard kit with doses of 0.1% bendiocarb, 0.05% deltamethrin, 0.75% permethrin and 4% DDT were used to detect knockdown time, mortality and resistance ratio of wild A. gambiae sensu lato. The questionnaire survey data was analyzed using descriptive statistics and one-way analysis of variance while susceptibility data was analysed by logistic regression with probit analysis using SPSS program. The WHO criteria was used to evaluate the resistance status of the tested mosquito populations., Results: A large proportion of respondents (80.8%) reported to have used insecticide mainly for farming purposes (77.3%). Moreover, 93.3% of household reported usage of long lasting insecticidal nets. The frequently used class of insecticide was organophosphate with chloropyrifos as the main active ingredients and dursban was the brand constantly reported. Very few respondents (24.1%) applied integrated vector control approaches of and this significantly associated with level of knowledge of insecticide use (P < 0.001). Overall knockdown time for A. gambiae s.l was highest in DDT, followed by Pyrethroids (Permethrin and deltamethrin) and lowest in bendiocarb. Anopheles gambiae s.l showed susceptibility to bendiocarb, increased tolerance to permethrin and resistant to deltamethrin. The most effective insecticide against the population from tested was bendiocarb, with a resistance ratio ranging between 0.93-2.81., Conclusion: Education on integrated vector management should be instituted and a policy change on insecticide of choice for malaria vector control from pyrethroids to carbamates (bendiocarb) is recommended. Furthermore, studies to detect cross resistance between pyrethroids and organophosphates should be carried out.

Background: Aedes aegypti (Diptera: Culicidae) is the main vector of the dengue virus globally. Dengue vector control is mainly based on reducing the vector population through interventions, which target potential breeding sites. However, in Tanzania, little is known about this vector's habitat productivity and insecticide susceptibility status to support evidence-based implementation of control measures. The present study aimed at assessing the productivity and susceptibility status of A. aegypti mosquitoes to pyrethroid-based insecticides in Dar es Salaam, Tanzania., Methods: An entomological assessment was conducted between January and July 2015 in six randomly selected wards in Dar es Salaam, Tanzania. Habitat productivity was determined by the number of female adult A. aegypti mosquitoes emerged per square metre. The susceptibility status of adult A. aegypti females after exposure to 0.05% deltamethrin, 0.75% permethrin and 0.05% lambda-cyhalothrin was evaluated using the standard WHO protocols. Mortality rates were recorded after 24 h exposure and the knockdown effect was recorded at the time points of 10, 15, 20, 30, 40, 50 and 60 min to calculate the median knockdown times (KDT 50 and KDT 95 )., Results: The results suggest that disposed tyres had the highest productivity, while water storage tanks had the lowest productivity among the breeding habitats Of A. aegypti mosquitoes. All sites demonstrated reduced susceptibility to deltamethrin (0.05%) within 24 h post exposure, with mortalities ranging from 86.3 ± 1.9 (mean ± SD) to 96.8 ± 0.9 (mean ± SD). The lowest and highest susceptibilities were recorded in Mikocheni and Sinza wards, respectively. Similarly, all sites demonstrated reduced susceptibility permethrin (0.75%) ranging from 83.1 ± 2.1% (mean ± SD) to 96.2 ± 0.9% (mean ± SD), in Kipawa and Sinza, respectively. Relatively low mortality rates were observed in relation to lambda-cyhalothrin (0.05%) at all sites, ranging from 83.1 ± 0.7 (mean ± SD) to 86.3 ± 1.4 (mean ± SD). The median KDT 50 for deltamethrin, permethrin and lambda-cyhalothrin were 24.9-30.3 min, 24.3-34.4 min and 26.7-32.8 min, respectively. The KDT 95 were 55.2-90.9 min for deltamethrin, 54.3-94.6 min for permethrin and 64.5-69.2 min for lambda-cyhalothrin., Conclusions: The productive habitats for A. aegypti mosquitoes found in Dar es Salaam were water storage containers, discarded tins and tyres. There was a reduced susceptibility of A. aegypti to and emergence of resistance against pyrethroid-based insecticides. The documented differences in the resistance profiles of A. aegypti mosquitoes warrants regular monitoring the pattern concerning resistance against pyrethroid-based insecticides and define dengue vector control strategies.

Background: The search for alternative trypanocidal compounds which can be available at affordable price is of paramount importance for control of trypanosomosis in human and animals. The current study evaluates the in vivo activity of ethanolic stem bark extracts on Trypanosoma congolense and selected immunological components in an inbred Swiss albino mouse model., Methods: Groups of mice infected with T. congolense were treated with the stem bark extracts at a rate of 1000 mg/kg, 1500 mg/kg, and 2000 mg/kg, twice a day in one set and thrice a day in another setting for three days consecutively. Negative (infected and untreated) and positive (infected treated with diminazene diaceturate at 3.5 mg/kg) control groups were used. Levels of parasitaemia were monitored daily for the first 10 days and thereafter 2-3 times per week to the end of experiment. In the other setting, uninfected mice, randomized in groups were treated with the extract but categorized as: thorough mixed extract (TME) and supernatant extract (SE) each at 500 mg/kg and 1500 mg/kg, in 8 hourly intervals respectively for three days consecutively. Control group was administered with phosphate buffered saline with glucose at 0.1 ml/10 g in a similar manner as for the extract. Whole blood and spleen were taken 24 h after the last treatment for hematological and histopathological analysis., Results: The groups that received the extracts at 8 hourly intervals drastically reduced the parasitaemia. The higher dose of SE significantly reduced the percentage of lymphocytes (P < 0.05). Both high and low dose of TME significantly reduced lymphocytes percent (P < 0.05) while percent of neutrophils and monocytes increased significantly (P < 0.05). Histopathological changes of the spleen in the mice treated with higher concentrations of the extract of C. swynnertonii were suggestive of lymphocytes toxicity., Conclusion: The current study has provided evidence that, in vivo trypanocidal activity of ethanolic bark extracts of C. swynnertonii is probably affected by its negative effect on humoral mediated immune response. Further studies are recommended to determine its potential as an alternative source of lead compounds for trypanocidal drug discovery.

Background: Indoor residual spraying (IRS) is one of the preferred tools used for control of malaria in many settings in the world. However, this control tool still faces challenges that include lack of long lasting active ingredient, limited number of well-trained personal, and need of repeated treatment which increases operational costs and reduces acceptability by residents. As a result there is need to develop and validate other methods which can complement the existing controls. The current study compared the bio-efficacy of durable wall lining (DL) (treated with deltamethrin 265 mg/m 2 ) and IRS (with deltamethrin 5% WP at 20 mg/m 2 ) on indoor mosquitoes densities and biting behaviour of mosquitoes in comparison with control houses without either DL or IRS., Methods: A study with two treatment arms and a control was conducted in Magugu ward, Northern Tanzania. Overall, a total of 60 houses were selected for the study with 20 houses per treatment arm and control. From each arm and control five houses were selected for mosquitoes trapping. Mosquitoes were sampled from 18:00 to 07:00 hourly every month for a period of 6 months. Mosquitoes were sampled using CDC miniature light traps., Results: A total of 14,400 female wild mosquitoes were used for contact bioassays in the control arm. 20 houses were sprayed, additionally walls of 20 houses were installed with wall liners, and walls of 20 unsprayed houses were used as control. Also, a total of 946 mosquitoes were sampled with traps in 60 houses during the hourly sampling for 6 months. A total of 3000 unfed females of An. gambiae s.l. wild population raised from larvae were collected from natural habitats in the same village for bioassays. The decline in indoor mosquitoes densities observed in this study did not lead to a shift in the biting cycles (P = 0.712). The number of mosquitoes caught indoors in houses with DL and IRS was significantly lower (P < 0.001) compared to control houses. When the comparisons were done between DL and IRS houses, the densities were significantly lower in DL houses compared to IRS houses (P = 0.021). In the DL installed houses, indoor mosquito density declined notably and sustained throughout the 6 months of the study. However, in those houses sprayed with deltamethrin 5% WP (PALI™5 WP), the density noted to start to increase within four months after spraying(do you mean to say that the densities declined up to 4 months post spraying and thereafter increased., Conclusions: Considering the efficacy duration of DL against IRS with deltamethrin 5% WP on mosquito densities decline indoors. The results of this study suggest that DL is more effective in malaria control as its efficacy lasted more than that of IRS.

Background: Larval source management (LSM), which requires an understanding of the ecology and composition of the local mosquito fauna, is an important parameter in successful vector control programmes. The present study was conducted to understand the distribution of larval habitats, species composition and factors associated with the seasonal abundance of mosquito larvae in Gezira irrigation Scheme in Gezira state, central Sudan., Methods: Cross-sectional larval surveys were carried out in the communities of Barakat (urban) and El-Kareiba (semi-urban), in Wad Madani, Gezira. A standard dipper was used for sampling larvae in all possible breeding sites and enamel bowls were employed for larvae sorting. Habitats were characterised using physical features and all larvae specimens were identified morphologically., Results: A total of 331 larval habitats were surveyed, out of which 166 were found to be positive breeding sites for Anopheles (56.78%), Culicinae (29.67%) and Aedes (13.55%) species. A total of 5 525 larvae collected were categorised as Culex (2 617, 47.37%), Anopheles (2 600, 47.06%) and Aedes (308, 5.57%). There was a high number of positive habitats during the rainy season, while the lowest proportion was reported during the hot dry season, in both study sites (Barakat [χ 2  = 10.641, P = 0.0090], El-Kareiba [χ 2  = 23.765, P = 0.0001]). The main breeding site for Anopheles larvae was leaking water pipes (51.5%), followed by irrigation channels (34.2%), hoof prints (6.4%), tyre tracks (5.5%) and water tanks (2.4%). A logistic regression analysis showed that the abundance of Anopheles larvae was reduced by the presence of predators (backswimmers, tadpoles) and grass cover. Adult productivity (number of adult females emerged/m 2 ) was not homogeneousfor all habitats; the highest productivity was found in irrigation channels (0.78 females/m 2 ) for Anopheles, and in septic tanks (2.86 females/m 2 ) for Culicinae and (0.86 females/m 2 ) for Aedes. Anopheles arabiensis was found to be the dominant Anopheles species. This study documented the presence of An. funestus in central Sudan for the first time., Conclusions: Maintaining leaking water pipes and adopting intermittent irrigation are recommended for LSM, as these surveyed habitats represent the main source of maintaining the local mosquito population during the hot dry season.