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Annona muricata L. is a plant commonly used in Southern Nigeria, for nutritional and medicinal purposes. This study was carried out to determine the larvicidal potentials of ethanol extract and fractions of the leaf of A. muricata. The ethanol leaf extract was subjected to phytochemical screening using standard protocol. The leaf crude extract and fractions (i.e., ethyl acetate and n-hexane) were used for larvicidal assay. The stock solution (5g each in 100ml of water) was prepared. From the stock solution 0.15, 0.30, 0.45, 0.60 and 0.75_ %w/v concentrations of extract and fractions were prepared and each concentration of the extract and fractions had 5 replicates. The control (100ml water and larval nutrient only) was also replicated . Twenty (20), third instar, larvae of Aedes aegypti were exposed to each extract concentration and fractions and their controls. Larval nutrient was added to each experimental set up. Observations were made after 24 and 48 hours exposure period. Phytochemical screening revealed the presence of some plant metabolites (alkaloids, saponins, tannins etc). Mortality of larvae exposed to the extract and fractions increased with increased in extract concentration and exposure time. This study revealed a differential potency of the extract and fractions used and a difference in susceptibility of larvae to the extract and fractions as evident by the 48hLC50 values obtained. Exposure of larvae to 0.75_ %w/v of ethanol extract and ethyl 50 acetate fraction resulted in 100 _% mortality after 48 hours exposure period. Probit analysis gave 48hr_LC values of 0.33 50 and 0.24_ %w/v for ethanol extract and ethyl acetate fraction, respectively. The n-hexane fraction was the least potent with 48h_LC50 value of 0.5461%w/v. Results obtained from this study suggest that the leaf extract and fractions of A. muricata hold potential as larvicides against Ae. aegypti. Its active ingredient should be isolated, characterized and formulated for use in larval habitats. [ABSTRACT FROM AUTHOR]

Arbovirus transmission by Aedes mosquitoes has long been a significant problem in Africa. In West Africa, Aedes vector management faces significant challenges; lack of recent Aedes distributional data and potential distributional modeling hinder effective vector control and pose serious public health issues. In this study, larval and adult mosquitoes were collected from four study sites in Enugu State, Nigeria every other month between November 2017 and September 2018. A total number of 2997 Aedes mosquitoes were collected and identified, and 59 positive field occurrence points for both Aedes adult and larvae were recorded. A total of 18 positive occurrence points were used for modeling. Ecological Niche Models (ENMs) were used to estimate the current geographic distribution of Aedes species ( spp. ) in Enugu State, south-east Nigeria, and mosquito presence was used as a proxy for predicting risk of disease transmission. Maximum Entropy distribution modeling or "MaxEnt" was used for predicting the potential suitable habitats, using a portion of the occurrence records. A total of 23 environmental variables (19 bioclimatic and four topographic) were used to model the potential geographical distribution area under current climatic conditions. The most suitable habitat for Aedes spp. was predicted in the northern, central, and southeastern parts of Enugu State with some extensions in Anambra, Delta, and Edo States in the west, and Ebonyi State in the east. Seasonal temperature, precipitation of the wettest month, mean monthly temperature range, elevation, and precipitation of the driest months were the highest estimated main variable contributions associated with the distribution of Aedes spp. We found that Aedes spp. prefer to be situated in environmental conditions where precipitation of wettest month ranged from 265 to 330 mm, precipitation of driest quarter ranged from 25 to 75 mm while precipitation of wettest quarter ranged from 650 to 950 mm. Aedes mosquitoes, such as Ae. aegypti and Ae. albopictus, pose a significant threat to human health, hence, the results of this study will help decision makers to monitor the distribution of these species and establish a management plan for future national mosquito surveillance and control programs in Nigeria., Competing Interests: All authors declare that there is no conflict of interest.

Background: Progress made in the control of malaria vectors globally is largely due to the use of insecticides. However, success in the fight against malaria has slowed down or even stalled due to a host of factors including insecticide resistance. The greatest burden of the disease is felt in Africa, particularly Nigeria. Unfortunately, adequate information on insecticide resistance is lacking in many parts of the country, particularly the South-East Zone. Hence, this study aims to bridge the information gap in the Zone., Methods: The study was conducted from April to December 2016. Anopheles gambiae (s.l.) larvae and pupae were collected from one community each, in the five states of the South-East Zone and reared to the adult stage. The adults were subjected to bioassays for insecticide resistance in accordance with the World Health Organization test procedures, across the four classes of insecticides used in public health. The mosquitoes were also subjected to molecular identification to the species level, and genotyped for West African knockdown resistance mutation (L1014F) and insensitive acetylcholinesterase-1 resistance mutation (G119S)., Results: The mosquitoes were susceptible (100%) to bendiocarb but resistant to pirimiphos-methyl (39.6%), deltamethrin (57%) and dichlorodiphenyltrichloroethane (DDT) (13%). Molecular analysis revealed that only An. gambiae (sensu stricto) was found in all the states except for Ebonyi, where only Anopheles coluzzii was present. High frequencies (0.6-0.9) of the L1014F mutation were found across the zone. The L1014F mutation was significantly higher in An. gambiae (s.s.) than in An. coluzzii (P < 0.0001). A relatively low frequency (0.2) of the G119S mutation was found in An. coluzzii, and only in Ebonyi State., Conclusion: The results show that mosquitoes collected from the South-East Zone of Nigeria were resistant to all insecticides used, except for bendiocarb. The presence of L1014F and G119S resistance mutations reported in this study calls for urgent attention to stop the growing threat of insecticide resistance in the country.