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The use of a metofluthrin-impregnated spatial repellent device (MSRD) is a new and effective method for preventing mosquito blood feeding. Indoor environmental factors such as room temperature and ventilation rate are thought to be important for MSRD activity. Measurements of room temperature and vaporization of metofluthrin from MSRD in typical rural metal-roof and thatched-roof houses in southeastern Malawi were conducted. The relationship between house structure and the number of collected Anopheline mosquitoes with and without MSRD treatment was also investigated. The difference between daytime and nighttime room temperature was significantly higher in metal-roof houses than in thatched-roof houses. The vaporization of metofluthrin from the MSRD was not accelerated by the high room temperature, but by the high indoor air flow by ventilation. The number of mosquito collections was significantly higher in thatched-roof houses than in metal-roof houses. MSRD-treated thatched-roof houses have a higher probability of mosquito infestation, but the vaporization of metofluthrin is also higher because of indoor air flow, resulting in a reduction in mosquito numbers. Metal-roof houses with closed eaves reduce the probability of mosquito invasion, and a longer predicted effectiveness occurs with MSRD because of the controlled release of metofluthrin through lower indoor air flow., Japanese Journal of Infectious Diseases, 75(3), pp. 288-295; 2022

Aedes aegypti (Linnaeus, 1762) is the main mosquito vector for dengue and other arboviral infectious diseases. Control of this important vector highly relies on the use of insecticides, especially pyrethroids. The high frequency (>78%) of the L982W substitution was detected at the target site of the pyrethroid insecticide, the voltage-gated sodium channel (Vgsc) of A. aegypti collected from Vietnam and Cambodia. Alleles having concomitant mutations L982W + F1534C and V1016G + F1534C were also confirmed in both countries, and their frequency was high (>90%) in Phnom Penh, Cambodia. Strains having these alleles exhibited substantially higher levels of pyrethroid resistance than any other field population ever reported. The L982W substitution has never been detected in any country of the Indochina Peninsula except Vietnam and Cambodia, but it may be spreading to other areas of Asia, which can cause an unprecedentedly serious threat to the control of dengue fever as well as other Aedes -borne infectious diseases.

Pyrethroid insecticides are the only pesticides approved for the treatment of head lice (pediculosis capitis) infestations in Japan. However, in Okinawa Prefecture, 96% of head lice are resistant to pyrethroids. Here, we conducted a clinical trial to assess the safety and efficacy of a dimethicone preparation against head lice infestations in Okinawa Prefecture. Dimethicone‐containing lotion was applied over the entire scalp three times over a 7‐day period. Lice bodies (nymphs/adults) and eggs (nits) were counted before (day 0) and after treatment (day 8); a subset of eggs was collected to estimate viability based on hatch rate. Efficacy was evaluated based on improvement (reduction) in head lice counts post‐treatment with respect to baseline. Safety was evaluated based on subjects’ scalp condition and adverse event incidence. Utility was a composite end‐point combining efficacy and safety. In total, 35 subjects were enrolled. Efficacy and safety were evaluated in 23 and 35 subjects, respectively. No side‐effects of note were reported during the treatment period. The dimethicone lotion resulted in a utility rating of “marginally useful” or higher in over 80% of the study population, signifying the formulation to be both safe and effective. The dimethicone lotion was also a potent ovicide; 99.4% of eggs collected after treatment failed to hatch when incubated. Eradication of head lice remained successful for at least 4 weeks after the final topical dimethicone application in 25 of the 28 subjects reached by telephone survey. Lice bodies and eggs were genotyped to analyze the prevalence of three knockdown resistance (kdr)‐type mutations within the voltage‐sensitive sodium channel known to confer pyrethroid resistance. One or more kdr mutations were confirmed in 30 of the 32 subjects from whom specimens were collected (93.8%). Dimethicone was confirmed to be both safe and effective in treating pyrethroid‐resistant head lice.

Long-lasting insecticidal nets (LLINs) experience some operational problems that reduce their effectiveness, such as limited spaces for hanging, biting of mosquitoes outdoors, a shift of key biting time from midnight to dawn or dusk, and development of pyrethroid resistance in mosquitoes. The concept of spatial repellency may be a countermeasure to overcome the above issues. The effect of the combined use of metofluthrin-impregnated spatial repellent devices (MSRDs) and LLINs (OlysetR Plus) on malaria prevalence and vector mosquitoes were examined in malaria endemic villages in south-eastern Malawi. The intervention reduced the infection rate in children as well as the number of pyrethroid-resistant vector mosquitoes. To achieve effective malaria control, continued intervention using MSRDs with 2 strips per 10 m2 at 3-month intervals to reduce the density of malaria mosquitoes is recommended., Japanese journal of infectious diseases, 73(2), pp.124-131; 2020

Increases in bed net coverage and antimalarial treatment have reduced the risk of malaria in sub-Saharan Africa. However, the pace of reduction has slowed, and new tools are needed to reverse this trend. We evaluated houses screened with insecticide-treated ceiling nets using a cluster randomized-controlled trial in western Kenya. The primary endpoints were Plasmodium falciparum PCR-positive prevalence (PCRPfPR) of children from 7 months to 10 years old and anopheline density. Ceiling nets and bed nets were provided to 1073 houses, and 1162 houses were provided with bed nets only. The treatment and control arms each had four clusters. We conducted three epidemiological and entomological post-intervention surveys over the course of a year and a half. Each epidemiological survey targeted 150 children per cluster, and entomological surveys targeted 25 houses. When the three surveys were combined, the median PCRPfPRs were 23% (IQR 8%) in the intervention arm and 42% (IQR 12%) in the control arm. The adjusted risk ratio (RR) was 0.53 [95% confidence interval (CI) 0.41–0.71; P = 0.029]. The median anopheline densities were 0.4 (IQR 0.4) and 2.0 (IQR 1.4), respectively. The adjusted RR was 0.41 (95% CI 0.29–0.90; P = 0.029). The present study indicates additional protection from insecticide-screened ceilings over the current best practice.

Aedes aegypti(Linnaeus, 1762) is the main mosquito vector for dengue and other arboviral infectious diseases. Control of this important vector highly relies on the use of insecticides, especially pyrethroids. Nevertheless, the development of pyrethroid resistance is a major obstacle to mosquito/disease control worldwide. Here, we focused on the mutations in the target site of pyrethroid insecticides, voltage-sensitive sodium channel (Vssc), and found thatAe. aegypticollected from Vietnam has the L982W allele in theVsscat a high frequency (>79%). L982W mutation is located in the highly conserved region ofVsscthat is associated with sodium–ion selectivity and permeation rate. Strains having the L982W allele showed similar or even higher levels of resistance to pyrethroids than those having V1016G, a typical knockdown resistance allele in Asia. Furthermore, concomitant mutations L982W+F1534C and V1016G+F1534C were confirmed, and strains having these multipleVsscmutations exhibited incomparably higher levels of pyrethroid resistance than any other field population ever reported. Molecular modeling analysis confirmed that these concomitant mutant alleles could interfere with approaching pyrethroid toVssc. Remarkably, >90% ofVsscofAe. aegyptiwere occupied by these hyper insecticide-resistant haplotypes in Phnom Penh city, Cambodia. Analysis of wholeVssccoding genes suggested thatVsscs have evolved into stronger resistant forms efficiently through gene recombination events. At this point, L982W has never been detected inVsscofAe. aegyptifrom any other neighboring countries. We strongly emphasize the need to be vigilant about these strong resistance genes spreading to the world through Indochina Peninsula.Significance StatementThe high frequency (>78%) of the L982W allele was detected at the target site of the pyrethroid insecticide, the voltage-sensitive sodium channel (Vssc) ofAedes aegypticollected from Vietnam and Cambodia. Haplotypes having concomitant mutations L982W+F1534C and V1016G+F1534C were also confirmed in both countries, and their frequency was high (>90%) in Phnom Penh, Cambodia. Strains having these haplotypes exhibited substantially higher levels of pyrethroid resistance than any other field population ever reported. The L982W mutation has never been detected in any country of the Indochina Peninsula except Vietnam and Cambodia, but it may be spreading to other areas of Asia, which can cause an unprecedentedly serious threat to the control of dengue fever as well as otherAedes-borne infectious diseases.

Background The Asian tiger mosquito, Aedes albopictus, has spread around the world. The migration was mainly mediated by maritime transportations. This species is known as an efficient vector for arboviruses, and it was responsible for the recent dengue outbreak in Tokyo, Japan. As the vector competence varies among geographical populations, and insecticide resistant populations have emerged, it is important to reveal their movements. The present study uses molecular techniques to search for a sign of introduction of an exotic population in three major international seaports on Kyushu Island. Methodology/principal findings Adults of Ae. albopictus were sampled around the international seaports of Fukuoka, Kitakyushu, and Nagasaki. Pairwise fixation indexes were estimated between the sampled populations based on 13 microsatellite markers. There was no clear genetic differentiation between distant and port populations in Kitakyushu and Nagasaki. However, the analysis found one distinct group near the container terminal in Fukuoka, which handles international freight containers mainly from adjacent countries. DNA samples were also obtained from Goto, Tsushima, Honshu, Ryukyu, Thailand, and the Philippines; and a cluster analysis and discriminant analysis revealed that the distinct group in Fukuoka did not belong to these groups. Combined with the results of phylogenetic analysis based on CO1, these results implied that this group originated from one Asian temperate region outside of Japan. Neutrality test and mismatch distribution analysis suggested that the establishment of this group was not recent. Conclusions/significance The present study found a sign of Ae. albopictus introduction from a temperate region of Asia through maritime freight container transportation. The genetically distinct group found in Fukuoka likely originated from a temperate region outside of Japan. Maritime container transportation may introduce to Japan mosquitoes with greater vector competence/insecticide resistance. This is the first study to describe the spatial population structure of Ae. albopictus in Japan using molecular techniques., Author summary Aedes albopictus is an invasive species and an efficient disease vector. The bioecological traits of this species and human-mediated transportations have fueled its worldwide spread. Because the levels of vector competence and insecticide resistance vary among geographical strains, the worldwide migration of this species is a concern for public health and vector control. While numerous studies have been done in non-native areas, within its native areas in Asia movements have not been explored. This study used molecular techniques to search for signs of introduction of an exotic population through three major international seaports on Kyushu Island, Japan. The present study found a genetically distinct group of Ae. albopictus near the container terminal in Fukuoka. The study suggests that its origin was one temperate region of East Asia outside of Japan, and the establishment of this group was not recent. As vector competence varies among different populations and the knock down resistance gene has been reported from some populations outside Japan, the risk of introducing mosquitoes with greater vector competence/insecticide resistance needs to be considered. This is the first study to describe the spatial population structure of Ae. albopictus in Japan using molecular techniques.

Malaria vectors have acquired an enzyme that metabolizes pyrethroids. To tackle this problem, we evaluated long-lasting insecticidal nets incorporating piperonyl butoxide (PBO-LLINs) with a community-based cluster randomized control trial in western Kenya. The primary endpoints were anopheline density and Plasmodium falciparum polymerase chain reaction (PCR)-positive prevalence (PCRpfPR) of children aged 7 months to 10 years. Four clusters were randomly selected for each of the treatment and control arms (eight clusters in total) from 12 clusters, and PBO-LLINs and standard LLINs were distributed in February 2011 to 982 and 1,028 houses for treatment and control arms, respectively. Entomological surveys targeted 20 houses in each cluster, and epidemiological surveys targeted 150 children. Cluster-level permutation tests evaluated the effectiveness using the fitted values from individual level regression models adjusted for baseline. Bootstrapping estimated 95% confidence intervals (CIs). The medians of anophelines per house were 1.4 (interquartile range [IQR]: 2.3) and 3.4 (IQR: 3.7) in the intervention and control arms after 3 months, and 0.4 (IQR: 0.2) and 1.6 (IQR: 0.5) after 10 months, respectively. The differences were –2.5 (95% CI: –6.4 to –0.6) and –1.3 (95% CI: –2.0 to –0.7), respectively. The datasets of 861 and 775 children were analyzed in two epidemiological surveys. The median PCRpfPRs were 25% (IQR: 11%) in the intervention arm and 52% (IQR: 11%) in the control arm after 5 months and 33% (IQR: 11%) and 45% (IQR: 5%) after 12 months. The PCRpfPR ratios were 0.67 (95% CI: 0.38, 0.91) and 0.74 (95% CI: 0.53, 0.90), respectively. We confirmed the superiority of PBO-LLINs., American Journal of Tropical Medicine and Hygiene, 105(2), pp. 461-471; 2021

Over the past decade, the success of long-lasting insecticidal nets (LLINs) in African countries has been countered by the rapid development of pyrethroid resistance in vector mosquitoes. Few studies have investigated the efficacy of LLINs in areas in which vector mosquitoes are resistant to pyrethroids. The use of excito-repellency chemicals may be bio-rational, because this type of repellency does not induce physiological resistance. However, limited information is available on the relationship between the mode of insecticide resistance and excito-repellency in pyrethroid-resistant mosquitoes. The aims of the present study were to investigate (1) differences in reactions to LLINs between individual and populations of vector mosquitos in an area in which multimodal pyrethroid resistance has developed, (2) the effects of LLINs on these malaria vectors, and (3) the development of new control techniques to supplement LLINs. Laboratory contact tests for repellency showed that resistant species governed by kdr (knockdown resistance) (Anopheles gambiae sensu stricto (s.s.)) lost repellency to pyrethroids, whereas those lacking kdr (Anopheles arabiensis and Anopheles funestus s.s.) maintained strong repellency irrespective of whether they possessed cytochrome P450-related metabolic resistance factors. LLINs were effective against these pyrethroid-resistant malaria vectors because they limited feeding on humans overnight. However, notable time shifts in human blood-feeding activity developed in An. arabiensis and An. funestus s.s., but not in An. gambiae s.s. These time shifts may be partially explained by differences in repellency by pyrethroids for these species. LLINs may not be effective because most blood feeding occurs when people are active outside of bed nets. Screening eaves with pyrethroid-impregnated wide-mesh nets was found to be effective in reducing human exposure to malaria vectors. The excito-repellency of pyrethroids, which act as a spatial barrier or reduce the feeding motivation of mosquitoes, may represent another countermeasure., Proceedings of the II International Symposium on Pyrethrum, August 6, 2015, Kyoto (Japan), Changing the title at the time of publication., Acta Horticulturae, 1169, pp.59-72; 2017

Long-lasting insecticidal nets (LLINs) experience some operational problems that reduce their effectiveness, such as limited spaces for hanging, biting of mosquitoes outdoors, a shift of key biting time from midnight to dawn or dusk, and development of pyrethroid resistance in mosquitoes. The concept of spatial repellency may be a countermeasure to overcome the above issues. The effect of the combined use of metofluthrin-impregnated spatial repellent devices (MSRDs) and LLINs (Olyset

Using mosquito larvae obtained from the field, a simplified bioassay for the detection of knockdown susceptibility is carried out on the day of collection. Each larva is placed in a glass vial with of water. An emulsifiable concentrate of d-T80-allethrin was diluted with water to obtain a solution. After releasing the larva, or of the solution was added in each vial to obtain a concentration of or , respectively. Twenty larvae from each site were used for each concentration regime. Larval knockdown was observed for . Larvae that sank to the bottom of the glass vial and could not swim, float, or were paralyzed were judged as knocked down larvae, and the time to knockdown was recorded for each larva. The median knockdown times (KT50s), i.e., the time required for 50% knockdown, were scored according to the 6 following categories: 1, < 5 min; 2, 5–10 min; 3, 10–15 min; 4, 15–20 min; 5, 20–30 min; and 6, > 30 min. The susceptibility index was calculated as the product of the scores at and . Thus, mosquitoes with a susceptibility index of 1 were considered to be the most susceptible, and those with a susceptibility index of 36 were considered to be the least susceptible to d-allethrin.

The impact of insecticide resistance in malaria vectors is poorly understood and quantified. Here a series of geospatial datasets for insecticide resistance in malaria vectors are provided, so that trends in resistance in time and space can be quantified, and the impact of resistance found in wild populations on malaria transmission in Africa can be assessed. Specifically, data have been collated and geopositioned for the prevalence of insecticide resistance, as measured by standard bioassays, in representative samples of individual species or species complexes. Data are provided for the Anopheles gambiae species complex, the Anopheles funestus subgroup, and for nine individual vector species. Data are also given for common genetic markers of resistance to support analyses of whether these markers can improve the ability to monitor resistance in low resource settings. Allele frequencies for known resistance-associated markers in the Voltage-gated sodium channel (Vgsc) are provided. In total, eight analysis-ready, standardised, geopositioned datasets encompassing over 20,000 African mosquito collections between 1957 and 2017 are released., Design Type(s)data integration objectiveMeasurement Type(s)insecticide resistanceTechnology Type(s)digital curationFactor Type(s)geographic location • temporal_intervalSample Characteristic(s)gambiae species complex • Africa • funestus subgroup • Anopheles gambiae • Anopheles arabiensis • Anopheles rivulorum • Anopheles pharoensis • Anopheles mascarensis • Anopheles funestus • Anopheles coluzzii • Anopheles melas • Anopheles quadriannulatus • Anophelinae Machine-accessible metadata file describing the reported data (ISA-Tab format)

We investigated the mode of entry of pyrethroids into the insect body using adult housefly, Musca domestica L., as an insect model. The wings of adult female houseflies were removed, and empenthrin was applied topically to three different sites: the mesothoracic spiracle, the ventral mesothorax, and the dorsal mesothorax. Among these treatments, the application of the compound to the mesothoracic spiracle led to the quickest knockdown of the flies. To determine the importance of the spiracle as a primary entry site for the pyrethroid, knockdown times were compared between houseflies with blocked and non-blocked spiracles, using two bioassays: a vapor action test using technical grade empenthrin, and a mosquito coil test using empenthrin-impregnated coils. In both tests, the times required for 50 % knockdown of spiracle-blocked houseflies were significantly higher than those required for the non-blocked flies. However, the mortality rates of the two groups were nearly identical, suggesting that spiracles play an important role in the knockdown of houseflies. These results also suggest that the rate of pyrethroid uptake through the spiracles was decreased due to the blocking of the mesothoracic spiracle. Therefore, the spiracle may be considered the main entry site for vaporized pyrethroids.

Background: When the first systematic list of mosquitoes in Nepal was reported in 1990, there was no description of Aedes aegypti (L.), while Aedes albopictus (Skuse) has been included in the Stegomyia subgroup since the 1950s. The first record of Ae. aegypti in Nepal was reported in 2009, suggesting some coincidence between the invasion of this species and the first record of dengue fever in Nepal in 2006. Results: We performed a field survey of the distribution and insecticide susceptibility of Ae. aegypti and Ae. albopictus in Nepal in 2017 and 2018. Mosquito larvae were collected from used tires located along the streets of Kathmandu, Bharatpur and Pokhara, and a simplified bioassay was used to assess the susceptibility of the larvae to pyrethroid insecticides using d-allethrin. The presence or absence of point mutations in the voltage-gated sodium channel was also detected by direct sequencing. V1016G was detected at a high frequency and a strong correlation was observed between the frequencies of V1016G and susceptibility indices in Ae. aegypti populations. F1534C was also detected at a relatively low frequency. In Ae. albopictus populations, susceptibilities to d-allethrin were high and no point mutations were detected. Analysis of the cytochrome c oxidase subunit 1 (cox1) gene was performed for assessing genetic diversity and the existence of two strains were identified in Ae. aegypti populations. One consisted of 9 globally-distributed haplotypes while the other was derived from an African haplotype. Conclusions: The high pyrethroid resistance, high V1016G frequency, and relatively low quantity of insecticides used to control dengue vectors in Nepal may have resulted in only weak selection pressure favoring insecticide resistance and could support the hypothesis that this species has recently been introduced from neighboring Asian countries where pyrethroid resistance is relatively widespread.[Figure not available: see fulltext.], Parasites & vectors, 13(1), p.213; 2020

SUMMARYChildren who sleep on the floor are less likely to use long-lasting insecticidal nets (LLINs); however, the relationship between sleeping location and Plasmodium falciparum infection has not been investigated sufficiently. This study revealed whether sleeping location (bed vs floor) is associated with P. falciparum infection among children 7–59 months old. More than 60% of children slept on the floor. Younger children were significantly more likely to sleep in beds [odds ratio, OR 2·31 (95% confidence interval (CI) 2·02–2·67)]. Nearly 70% of children slept under LLINs the previous night. LLIN use among children who slept on the floor was significantly less than ones sleeping in beds [OR 0·49 (95% CI 0·35–0·68)]. The polymerase chain reaction (PCR) based P. falciparum infection rate and slide based infection rate were 65·2 and 29·7%, respectively. Both infections were significantly higher among children slept on the floor [OR1·51 (95% CI 1·08–2·10) for PCR base, OR 1·62 (95% CI 1·14–2·30) for slide base] while net availability was not significant. Sleeping location was also significant for slide based infection with fever (⩾37·5 °C) [2·03 (95% CI 1·14–3·84)] and high parasitemia cases (parasite ⩾2500 µL−1) [2·07 (95% CI 1·03–4·50)]. The results suggest that sleeping location has a direct bearing on the effectiveness of LLINs.

The occurrence of natural hybridization between the mosquitoes Culex pipiens pallens and Cx. pipiens f. molestus in Northwestern Kyushu, Japan, was confirmed based on morphology and molecular methods. In order to assess the morphological difference in male genitalia of the two forms on the basis of the dorsal/ventral (D/V) ratio, mosquito egg rafts were collected in Nagasaki City using oviposition traps. The morphological parameters of male genitalia from Cx. pipiens f. molestus were discontinuous with those from Cx. pipiens pallens, while intermediate individuals could be found in a single egg raft. These individuals were identified as hybrids using a polymerase chain reaction (PCR)-based assay. The fitness of the family descended from hybrids was lower than that from typical pallens and molestus families, as measured by egg raft size and egg hatchability. The reduced fitness of the hybrids suggested that the genetic introgression between the two forms could be restricted.

The overexpression of Kir3.2, a subunit of the G protein-gated inwardly rectifying K(+) channel, is implicated in some of the neurological phenotypes of Down syndrome (DS). Chemical compounds that block Kir3.2 are expected to improve the symptoms of DS. The purpose of this study is to develop a cell-based screening system to identify Kir3.2 blockers and then investigate the mode of action of the blocker. Chemical screening was carried out using a K(+) transporter-deficient yeast strain that expressed a constitutively active Kir3.2 mutant. The mode of action of an effective blocker was electrophysiologically analyzed using Kir channels expressed in Xenopus oocytes. Proflavine was identified to inhibit the growth of Kir3.2-transformant cells and Kir3.2 activity in a concentration-dependent manner. The current inhibition was strong when membrane potentials (Vm) was above equilibrium potential of K(+) (EK). When Vm was below EK, the blockage apparently depended on the difference between Vm and [K(+)]. Furthermore, the inhibition became stronger by lowering extracellular [K(+)]. These results indicated that the yeast strain serves as a screening system to isolate Kir3.2 blockers and proflavine is a prototype of a pore blocker of Kir3.2.

Residents of Vietnam living in areas with water shortages and/or poor tap water maintain water storage containers, such as jars, in and around their domiciles in order to store water used in daily life. Although these water jars are known to be important breeding sources of the Aedes mosquito, use of chemical larvicides in such containers is legally prohibited in Vietnam. In this study, we identified the dominant mosquito insect predators in water jars in and around residences located in Tan Chanh, Long An, southern Vietnam. Of 3,646 Heteroptera collected from such jars, Corixidae (Micronecta spp.) and Veliidae (Microvelia spp.) were revealed to be the dominant predators. Polymerase chain reaction (PCR) analysis revealed that 40% of Micronecta and 12% of Veliidae had Aedes aegypti-positive reactions, indicating that these two dominant Heteroptera are important predators of Ae. aegypti. Our results suggest that aquatic Heteroptera may be an important mosquito control agent in addition to the currently used copepods.

BACKGROUND: Although insecticidal aerosols have been widely accepted for household use, the discharged amount should be maintained at minimum levels because they contain volatile organic compounds. Hence, it would be valuable to develop a technique whereby insecticide droplets adhere efficiently to an insect’s body. The present study was undertaken in order to clarify how differences in the mode of adhesion to the insect body influence the knockdown effect. RESULTS: When the discharged volume of droplets with different diameters was the same, the adhesion volume of larger droplets was twice that of smaller droplets, resulting in a higher insect knockdown. In contrast, when the adhesion volume of the two droplet types was the same, a greater number of smaller droplets than larger droplets adhered, and the smaller droplets caused higher insect knockdown. The knockdown effect of both droplet types was lowered when the mesothoracic spiracles of cockroaches were blocked; however, the effect of larger droplets was lowered to a lesser degree. CONCLUSION:Theresultssuggestthat,theprobabilityofadhesiontothemoresusceptibleregionsofaninsect’sbody,i.e.,areas surrounding the mesothoracic spiracles, was improved when a greater number of smaller droplets were adhered, resulting in higher knockdown. c � 2011 Society of Chemical Industry

Polymerase chain reaction analysis was performed to determine whether mosquito predators in wetland habitats feed on Anopheles gambiae sensu lato (s.l.) larvae. Aquatic mosquito predators were collected from six wetlands near Lake Victoria in Mbita, Western Kenya. This study revealed that the whole positive rate of An. gambiae s.l. from 330 predators was 54.2%. The order of positive rate was the highest in Odonata (70.2%), followed by Hemiptera (62.8%), Amphibia (41.7%), and Coleoptera (18%). This study demonstrates that the polymerase chain reaction method can determine whether aquatic mosquito predators feed on An. gambiae s.l. larvae if the predators have undigested An. gambiae s.l. in their midgut or stomach.

This study aimed to evaluate the effects of existing practices of residents in reducing pre-adult Aedes aegypti (L.) infestation and to assess the effect of dengue-related knowledge on the practices. A house-to-house survey was conducted in two areas with different socioeconomic status in Ho Chi Minh City between October and November 2007. Some residents in both the areas used covers on the productive containers such as the jars and plastic buckets (i.e., 58% and 81% in the two study areas), and it was effective in reducing Ae. aegypti infestation: odds ratio (OR) of 4.0 and 4.9 (95% confidence interval [CI]: 1.49-10.76 and 1.2-19.57, respectively) for the containers with inappropriate covers compared with those with appropriate covers in the two areas, respectively. Appropriate cover use was an effective practice; however, no beneficial role of the knowledge related to dengue in promoting the practice was identified., The American journal of tropical medicine and hygiene, 80(5), pp.752-757; 2009

The penetration route of adhered pyrethroids following direct aerosol spraying was studied in the German cockroach (Blattella germanica) by investigating the relationship between the application site of insecticide and knockdown efficacy. In direct spray, KT50 was 26.4 s and the adhered amount of pyrethroid was 0.745 μg. On the contrary, required amount of pyrethroid to obtain the same KT50 was one-eighth in topical application to the mesothoracic spiracle, while 2.6 times to the ventral mesothorax. KT50 of cockroaches with blocked mesothoracic spiracles was greater than those with unblocked spiracles by 1.8-fold. The amount of directly sprayed pyrethroid penetrating through the inner wall of the mesothoracic trachea was significantly higher than the amount penetrating through the body wall of the ventral mesothorax. Therefore, the knockdown effect of the direct spray was believed to be caused by the flow of pyrethroids into the mesothoracic spiracles and its subsequent penetration through the inner wall of the mesothoracic trachea., Pesticide Biochemistry and Physiology, 91(3), pp.135-140; 2008

The fecundity and survival of 6 copepod species were assessed under laboratory conditions in order to choose the best candidates to control the aquatic stages of dengue mosquitoes in the field. Females of all the 6 species (Mesocyclops aspericornis, Mesocyclops pehpeiensis, Mesocyclops woutersi, Mesocyclops thermocyclopoides, Mesocyclops ogunnus, and Megacyclops viridis) mated more than once. Multiple mating resulted in increased egg production. The reproductive ability and longevity varied among the species, and M. aspericornis had the highest values. The lowest values were observed in M. thermocyclopoides. Multiple mating of males of M. aspericornis was also observed. The paternal fecundity decreased with each additional mating. There was no difference in the paternal fecundity between the males that mated at low and high female frequencies. The sperm stored in the M. aspericornis females remained viable for 30 days after storage under moist conditions at 25 degrees C or 15 degrees C. This feature in M. aspericornis represents an additional positive factor indicating that this species is a good biological agent for controlling mosquito larvae, especially in domestic water containers that may dry intermittently., Journal of the American Mosquito Control Association, 24(1), pp.61-69; 2008

Background Yellow fever is endemic in some countries in Africa, and Aedes aegpyti is one of the most important vectors implicated in the outbreak. The mapping of the nation-wide distribution and the detection of insecticide resistance of vector mosquitoes will provide the beneficial information for forecasting of dengue and yellow fever outbreaks and effective control measures. Methodology/Principal Findings High resistance to DDT was observed in all mosquito colonies collected in Ghana. The resistance and the possible existence of resistance or tolerance to permethrin were suspected in some colonies. High frequencies of point mutations at the voltage-gated sodium channel (F1534C) and one heterozygote of the other mutation (V1016I) were detected, and this is the first detection on the African continent. The frequency of F1534C allele and the ratio of F1534C homozygotes in Ae. aegypti aegypti (Aaa) were significantly higher than those in Ae. aegypti formosus (Aaf). We could detect the two types of introns between exon 20 and 21, and the F1534C mutations were strongly linked with one type of intron, which was commonly found in South East Asian and South and Central American countries, suggesting the possibility that this mutation was introduced from other continents or convergently selected after the introgression of Aaa genes from the above area. Conclusions/Significance The worldwide eradication programs in 1940s and 1950s might have caused high selection pressure on the mosquito populations and expanded the distribution of insecticide-resistant Ae. aegypti populations. Selection of the F1534C point mutation could be hypothesized to have taken place during this period. The selection of the resistant population of Ae. aegypti with the point mutation of F1534C, and the worldwide transportation of vector mosquitoes in accordance with human activity such as trading of used tires, might result in the widespread distribution of F1534C point mutation in tropical countries., Author Summary Aedes aegpyti is one of the most important vectors of yellow fever and dengue fever. Pyrethroid insecticides are emerging as the predominant insecticides for vector control, and resistance of vector mosquitoes to pyrethroid is a major problem for the vector control program. Several mutations in the voltage-gated sodium channel were reported to play important roles in pyrethroid resistance of Aedes aegypti. Recently, a novel F1534C mutation was reported to be strongly correlated with resistance to DDT and pyrethroid. We observed a high resistance to DDT and moderate resistance to permethrin in both Ae. aegypti aegypti (Aaa) and Ae. aegypti formosus (Aaf) colonies collected in Ghana. Concurrently, high frequencies of F1534C mutations were found in the above mosquito colonies, and this was its first detection on the African continent. We found a strong linkage of F1534C mutation and the introns between exon 20 and 21 commonly found in South East Asian and South and Central American countries. The DDT and pyrethroid resistance in Ghanaian Ae. aegypti population was suggested to be caused by the introgression of Aaa genes from the above area.

We investigated the mode of entry of pyrethroids into the insect body using adult housefly, Musca domestica L., as an insect model. The wings of adult female houseflies were removed, and empenthrin was applied topically to three different sites: the mesothoracic spiracle, the ventral mesothorax, and the dorsal mesothorax. Among these treatments, the application of the compound to the mesothoracic spiracle led to the quickest knockdown of the flies. To determine the importance of the spiracle as a primary entry site for the pyrethroid, knockdown times were compared between houseflies with blocked and non-blocked spiracles, using two bioassays: a vapor action test using technical grade empenthrin, and a mosquito coil test using empenthrin-impregnated coils. In both tests, the times required for 50 % knockdown of spiracle-blocked houseflies were significantly higher than those required for the non-blocked flies. However, the mortality rates of the two groups were nearly identical, suggesting that spiracles play an important role in the knockdown of houseflies. These results also suggest that the rate of pyrethroid uptake through the spiracles was decreased due to the blocking of the mesothoracic spiracle. Therefore, the spiracle may be considered the main entry site for vaporized pyrethroids.

The role of Anopheles funestus group in malaria transmission was investigated in Bagamoyo coastal Tanzania, in the process of characterizing the area as a malaria vaccine testing site. Mosquitoes were sampled inside houses and multiplex PCR was used to identify 649 specimens. The following species were found: A. funestus s.s. (84.3%), A. leesoni (13.6%), A. rivulorum (1.5%) and A. parensis (0.6%). Multiplex PCR of 147 blood-fed specimens showed that over half (57.1%) of the identifiable blood meals were taken from human hosts, and human blood index in A. funestus and A. leesoni was 55% and 82% respectively. Plasmodium falciparum infection rate determined by nested PCR was 11% in A. funestus s.s. Although the abundance was low, 26 specimens of A. leesoni, two of A. rivolurum and one of A. parensis were found positive for P. falciparum. The presence of four A. funestus species in Tanzania emphasizes the relevance to define precisely their spatial and temporal distribution, specific behaviour, ecology and exact role in malaria transmission.

The behavioral responses of Aedes aegypti (L.) and Aedes albopictus (Skuse) adults to several attractive cues, as reactions to mosquito traps, are compared in the laboratory, and differences in the primary attractive factors for both species are discussed. Target-attacking frequency of unfed Ae. aegypti females was 30 times that of unfed Ae. albopictus females under simulated conditions. Changes in the percentage of trapped mosquitoes under several attractive conditions using commer- cial mosquito traps showed that Ae. aegypti mosquitoes were trapped 2Ð3 times faster than Ae. albopictus. For Ae. aegypti, the combination of a visual cue CO2 alone enhanced attractiveness, whereas both a visual cue CO2 as well as a visual cue octenol enhanced Ae. albopictus. The combination of at least three factors, such as a visual cue, CO2, and a chemical cue is thought to be valuable for trapping and estimating the relative adult population sizes ofAe.aegypti andAe.albopictus in the Þeld.

Residents of Vietnam living in areas with water shortages collect and store tap water, when it is available, in containers, such as jars, which is then used for their daily activities. Although these water jars are important breeding sites for mosquitoes, Vietnam legislation prohibits the use of chemical larvicides in such containers. The effect of Olyset Net on the abundance of mosquito larvae and their Heteroptera predators (Micronecta spp. and Veliidae) in jars was evaluated via field experiments conducted in Tan Chanh, Long An, Vietnam. The number of Aedes larvae decreased when the jars were covered with the Olyset Net, while the numbers of non-Aedes mosquito larvae (Culex and Anopheles), and those of Micronecta and Veliidae, did not vary until the end of the experiment. However, Micronecta population increased after removing the Olyset Net from the jars, and consequently Aedes larvae decreased due to these changes in the Micronecta, 26 days after the Olyset Net was removed. Incomplete use of Olyset Net failed to control mosquitoes in water jars based on the invasion of adult mosquitoes, and in water transferred by residents among the jars, which might contain larvae. These results suggest that Micronecta, as well as Olyset Net, can be considered as control agents for mosquito larvae.

EcoBio-Block® S, a novel controlled release system (CRS) for the insect growth regulator pyriproxyfen, uses a water-purifying concrete block system (EcoBio-Block) composed of a porous volcanic rock and cement, and it incorporates the aerobic bacterial groups of Bacillus subtilis nallo. EcoBio-Block S showed high inhibitory activity against mosquito emergence as well as a water-purifying effect. Chemical analysis and bioassay showed that EcoBio-Block S provides a high-performance CRS that controls the release of pyriproxyfen at low levels according to "zero order kinetics."