[Sugar-Supplemented Substrates Contaminated by Agricultural Inputs Favor the Proliferation of Aedes albopictus...

Originating from South-East Asian tropical forests, Aedes albopictus (Skuse) (Diptera: Culicidae) is a mosquito of great genetic plasticity, which allowed it to adapt to a large variety of environments including the urban ones. Yet many a city nowadays comprises peri urban zones close to land devoted to farming. The sites where Ae. albopictus live and reproduce, located on the fringe of nectarfilled blossoming crops (orchards, colza and sunflower fields) are often polluted by chemical inputs such as fertilizers and pesticides. In this laboratory study we have assessed the impact of sugar-supplemented solutions contaminated by NPK fertilizer and/or by diflubenzuron or pyriproxyfen insecticides on adults of Ae. albopictus mosquitoes. The results have shown that the females feeding on a sweetened solution containing NPK fertilizer laid a significantly greater number of eggs. However when the sweetened solutions contained diflubenzuron or pyriproxyfen insecticides, the actions of both combinations resulted in a noticeable reduction of the numbers of eggs laid and the ones hatching. Finally when the sweetened solutions had been jointly polluted by the fertilizer and either one of the larvicides, the sterilizing effect of the insecticides was completely obliterated regarding both the numbers of eggs laid and the ones hatching. We are led to conclude that the somewhat inconsistent use of pesticides and fertilizers in agriculture bring about new ecological systems favorable to the proliferation of mosquitoes.