Evaluation au laboratoire de l'effet de l'exposition à des CMEO d'intrants agricoles sur le développement et la reproduction d'Anophèles Coluzzii Coetzee, 2013 (Diptera: Culicidae), vecteur majeur du Paludisme

Abstract

Mosquitoes of the genera Anopheles constitute a major preoccupation as vectors of diseases like malaria and filarial and are essentially controlled with the help of insecticide. The mediums in which anopheles larvae develops are aquatic ecosystems subjected to xenobiotic of anthropic origin capable of modifying their sensitivity to insecticide. To verify this hypothesis, we aim at studying the prolonged impact of two agricultural inputs on the reproduction and development of malaria major vector Anopheles coluzzii. The study consisted in carrying out the tests of range to determine the Lowest Observed Effect Concentration (LOEC), then to expose the larvae of mosquitos to these LOEC in order to evaluate the effect on their reproduction and their development. In addition, the physico-chemical analysis was carried out. The LOEC was of 2×10 -8g/L for the cypercal and 0.2 g/L for ammonia. The physico-chemical analyses reveal that contrary to the cypercal, ammonia varies significantly the pH and the electric conductivity compared to the witness sample. The observations made on the productivity of the breeding of the emergent adult mosquitoes of the larvae exposed to xenobiotic showed a weak reproductive success compared to the witness. Thus with the first generation, fecundity was lower for the tests than for the witnesses (the average number of laid eggs passed from 123.16 ± 44.82 for the witness to 92 ± 28.44 and 92.19 ± 34.07 respectively for the cypercal and the ammonia) just as the fertility (the percentage of eggs hatching was 80.04 for the witness, 67.56 for the cypercal and 69.52 for ammonia). The larval rate of survival, the rate of nymphose, the rate of emergence, the rate of inhibition of emergence, the preimaginal yield and the total yield were also weaker for the tests than for the witnesses. With the second generation, the parameters of growth continued to drop but slightly for ammonia while the cypercal made decrease by advantage and significantly these parameters except for the rate of eggs hatching and the rate of larval survival. This information contributes to a better comprehension of the impact of anthropic environment on the adaptive capacities of the mosquitoes with respect to the pollutants present in the larval breeding sites and opens prospects for research on the cost of resistance to insecticides on the dynamics of the populations of mosquito.