Anopheles gambiae Larval Development and Toxicity’s Reduction of Conventional Agriculture Insecticides in the Laboratory Conditions
Henri Gabriel Tsila *
Department of Animal Biology, Faculty of Science, University of Dschang, Biology and Applied Ecology Unit Research, P.O. Box 67, Dschang, Cameroon and Department of Animal Biology, Faculty of Science, Vector Borne Infectious Diseases Laboratory, University of Dschang, P.O. Box 67, Dschang, Cameroon.
Alvine Larissa Meyabeme Elono
Forestry Department, Faculty of Agronomy and Agricultural Science, University of Dschang, P.O. Box 22, Dschang, Cameroon.
Patrick Akono Ntonga
Department of Animal Organisms, Biology and Physiology of Animal Organisms Laboratory, University of Douala, P.O Box 24 157, Douala, Cameroon.
Timoléon Tchuinkam
Department of Animal Biology, Faculty of Science, University of Dschang, Biology and Applied Ecology Unit Research, P.O. Box 67, Dschang, Cameroon and Department of Animal Biology, Faculty of Science, Vector Borne Infectious Diseases Laboratory, University of Dschang, P.O. Box 67, Dschang, Cameroon.
Mpoame Mbida
Department of Animal Biology, Faculty of Science, University of Dschang, Biology and Applied Ecology Unit Research, P.O. Box 67, Dschang, Cameroon.
*Author to whom correspondence should be addressed.
Abstract
Background: Vector control of Malaria is mainly made by using impregnated bed nets and insecticides pulverizations indoor or/and outdoor. Besides, appearance and development of resistance’s phenomenon among mosquito populations to insecticides, constitute a significant obstacle this fighting.
Aims: To highlighting a neutralization phenomenon of three insecticides (methyl-parathion, dimethoate and cypermethrin) during development of the Anopheles gambiae s.s. larvae.
Methodology: Two setups followed one after the other were designed. In setup 1, four concentrations (with four replicates each) were freshly prepared and independently received a first batch of 100 first instars An. gambiae s.s. After emergence of adults from this first batch, the same test media were simply filtered and received a second batch of first instars larvae to make setup 2. Three endpoints were measured in this study: the duration of larval phase, the larval mortality, and the size of adults.
Results: The development duration and mortality of larvae decreased significantly at setup 2 with cypermethrin and methyl-parathion. Thus, the duration of larval stage decreased from 10.18 days at setup 1 to 7.84 days at setup 2 for 0.010 µg/l (highest concentration) with cypermethrin and from 10.20 days at setup 1 to 8.27 days at setup 2 for 0.144 µg/l (highest concentration) with methyl-parathion. The larval mortality dropped from 79.32 % at setup 1 to 12.00 % at setup 2 for the highest concentration of cypermethrin and from 76.42 % at setup 1 to 12.50 % at setup 2 for the highest concentration of methyl-parathion. While adults size significantly increased in setup 2. For males, wing’s length increased from 3.28 mm at setup 1 to 3.49 mm at setup 2 for the highest concentration of cypermethrin, from 3.31 mm at setup 1 to 3.49 mm at setup 2 for the highest concentration of methyl-parathion. In female, wing’s length increased from 3.52 mm at setup 1 to 3.68 mm at setup 2 for the highest concentration of cypermethrin, from 3.49 mm at setup 1 to 3.68 mm at setup 2 for the highest concentration of methyl-parathion.
Conclusion: This work shows that mosquito larvae, especially An. gambiae are able to modify breeding medium to improve its fitness during their development.
Keywords: Anopheles gambiae, larvae, toxicity, tolerance, life's traits