Abstract
Background: Theinsecticide susceptibility status of Anopheles funestus, one of the main malaria vectors inthe Afrotropicalregions, remains under-studied due to the difficulty of working with this mosquito species. Collecting their larvae in natural breeding sites, rearing and maintaining them in normal laboratory conditions have been a difficult task. Forced-egg laying technique has been a very good tool to generate eggs from adult mosquitoes collected from the wild but rearing these eggs to obtain satisfying portion as adults has always been the problem. In this study, we optimized the development of mosquito species larvae under standard laboratory conditions for desired production of adult mosquitoes that can be useful for insecticide susceptibility tests. Methods: A forced-egg laying technique was used to obtain eggs from gravid female Anopheles funestus collected from Kpome locality in Benin. Eggs were reared in three different water samples (water from the borehole,and two mineral water namely FIFA and Possotômè) and larvae were fed with TetraMin baby fish food. The physico-chemical parameters of the waters were investigated prior to use for egg incubation. Results:In contrast to mineral water that had no contamination, the borehole water source was contaminated with lead (2.5mg/L) and nitrate (118.8mg/L). Egg hatching rates ranged as 91.9 ± 4.4%, 89.1 ± 2.5% and 87.9 ± 2.6% in FIFA, Possotômè and borehole water respectively. High emergence of larvae to adult mosquitoes was recorded as in FIFA (74.3%) and Possotômè(79.5%) water. No adult mosquito was obtained from larvae reared in borehole water. Conclusions: This study gave insight on the water sources that could be good for rearing to mass produce An. funestus in the laboratory. More analysis with other local mineral water sources in our environments could be considered in the future, hopefully giving better outputs.
Highlights
Anopheles funestus remains a main malaria vector, and is thereby responsible for malaria morbidity and mortality inSub-Saharan Africa[1]
Twenty-four hours post-oviposition, eggs from a single mosquito were divided into 3 batches and were allowed to hatch in small cups for larvae emergence, which were later transferred into rearing bowls containing 3 different types of water (Borehole water collected in Calavi and local mineral water namely FIFA and Possotômè) (Figure 1)
These results showed that Possotômè mineral water had a pH of 7.9 whereas the pH obtained with FIFA mineral water and borehole water were 5.9 and 6.2, respectively
Summary
Breeding of this mosquito species like other mosquitoes requires an aquatic environment where larvae emerge to adult mosquitoes. An. funestus, unlike the other known malaria vector, An. gambiae, in Sub-Saharan Africa breeds in natural/artificial permanent and semi-permanent water bodies with floating or emerging vegetation like edges of swamps, in weedy and grassy parts of rivers, streams, furrows, ditches and ponds with low salinity and little richness in organic matter[6]. The insecticide susceptibility status of Anopheles funestus, one of the main malaria vectors in the Afrotropical regions, remains under-studied due to the difficulty of working with this mosquito species. Collecting their larvae in natural breeding sites, rearing and maintaining them in normal laboratory conditions have been a difficult task. More analysis with other local mineral water sources in our environments could be considered in the future, hopefully giving better outputs
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