Abstract The need for evidence-based data, to inform policy decisions on malaria vector control interventions in Nigeria, necessitated the establishment of mosquito surveillance sites in a few States in Nigeria. In order to make evidence-based-decisions, predictive studies using available data becomes imperative. We therefore predict the distribution of the major members of the Anopheles gambiae s.l. in Nigeria. Immature stages of Anopheles were collected from 72 study locations which span throughout the year 2020 resulted in the identification of over 60,000 Anopheline mosquitoes. Of these, 716 breeding sites were identified with the presence of one or more vector species from the An. gambiae complex and were subsequently used for modelling the potential geographical distribution of these important malaria vectors. Maximum Entropy (MaxEnt) distribution modeling was used to predict their potentially suitable vector habitats across Nigeria. A total of 23 environmental variables (19 bioclimatic and four topographic) were used in the model resulting in maps of the potential geographical distribution of three dominant vector species under current climatic conditions. Members of the An. gambiae complex dominated the collections (98%) with Anopheles stephensi, Anopheles coustani, Anopheles funestus, Anopheles moucheti, Anopheles nilli also present. An almost equal distribution of the two efficient vectors of malaria, An. gambiae and Anopheles coluzzii , were observed across the 12 states included in the survey. Anopheles gambiae and Anopheles coluzzii had almost equal, well distributed habitat suitability patterns with the latter having a slight range expansion. However, the central part of Nigeria (Abuja) and some highly elevated areas (Jos) in the savannah appear not suitable for the proliferation of these species. The most suitable habitat for Anopheles arabiensis was mainly in the South-west and North-east. The results of this study provide a baseline allowing decision makers to monitor the distribution of these species and establish a management plan for future national mosquito surveillance and control programs in Nigeria.
The effect of plant oil treatments extracted from Khaya ivorensis and Azadirachta indica was evaluated on adult maize weevils Sitophilus zeamais reared on maize grain.Four replicates of each treatment oils were constituted at 0% (control untreated), 1 ml, 2 ml, and 3 ml doses.Each of the pytochemical oil and the synthetic chemical (Daksh-Dichlorvos 100% EC w/v) was introduced into experimental jars (300 cm 3 ) at graded levels, before 20 g of clean maize grain was incorporated.The treatment oils were separated from the grains with perforated white paper, before 10 newly emerged adult S. zeamais was added to the experimental jars including the control (untreated) experiment, which contain 20 g of maize grain but no treatment was added.The plant oils were evaluated for their toxic effect on S. zeamais, oviposition, F1 progeny emergence, grain damage and weight loss.Data collected were analyzed using ANOVA.The means were separated using LSD at P>0.05.The results revealed that treatment oils were toxic to the maize weevils when compared with the control (untreated) experiment.Among the plants, essential oil of K. ivorensis significantly (P>0.05)suppressed egg laying, F1 progeny emergence and grain damage.Therefore, the essential oil of K. ivorensis and A. indica is useful in the control of S. zeamais.
