Agriculture has to face great challenges which are the increased needs for food of a growing population and the protection of the environment. Crop protection against pest insects is one of the major component to keep and improve crop yields. Insecticides were used as the main pest management tools over a long period of time. Nevertheless, their widespread uses during several decades have led to the emergence of resistant insects. The various mechanisms of resistance have been well-studied. However, these last years, scientists have brought their attention on the effect of sublethal doses of insecticides that could contribute to the development of insect resistance. Following a field application of insecticides, a spatial and temporal dispersal of compounds could occur and insects may be exposed to different doses. We focused our work on the molecular and cellular changes induced by an exposure to sublethal doses of insecticides. We demonstrated on the cockroach <i>Periplaneta americana</i> that a chronic exposure to a sublethal dose of a neonicotinoid imidacloprid is sufficient to induce molecular changes leading to a loss of imidacloprid sensitivity. Moreover, this effect is maintained over time even if the cockroaches were no longer exposed to imidacloprid. Thus, cockroaches are able to develop adaptation mechanisms leading to modification of their sensitivity to this insecticide. Using biochemical and molecular experiments, we showed that the main actors in this adaptation phenomenon are the acetylcholine nicotinic receptors. In order to develop new strategies in pest control, we reversed the loss of sensitivity observed in acclimated cockroaches using interference RNA targeting an acetylcholine nicotinic receptor subunit. Thus, sublethal doses of insecticides induce many effects which should be taken into account for pest management.

Exposure to sublethal doses of insecticides can induce insecticide sensitivity changes linked to molecular and cellular modifications

ACS Fall 2021

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