Agrochemicals, Even in Non-Lethal Doses, Threaten the Survival of Non-Pest Insects

Exposure to agrochemicals, even in doses too low to kill insects, causes significant damage to their behavior, development and reproduction, which is aggravated when the temperature rises, according to a study published in Science. The research analyzes the effects of 1,024 molecules – insecticides, herbicides, fungicides, plant growth inhibitors – on the fruit fly Drosophila melanogaster and on other insects.

This is an impressive study because of the breadth of pesticides tested (over a thousand) and because of its experimental design that covers not only individual chemicals, but several mixtures in a gradient of realistic concentrations. In addition, it includes effects on mosquito larvae and butterfly caterpillars to compare results.

The merit of this work is in demonstrating that insect exposure to non-lethal pesticide residues is of more importance than might be thought. Of greater concern are the negative effects of a cocktail of molecules on reproduction. This confirms what we already indicated a few years ago, saying that pesticides – not only insecticides, but all other plant protection products on the market – are a major cause of insect decline, even more so than climate change. In fact, the study confirms that temperature only increases the magnitude of the effects of those chemicals, but it is clear that such effects would not occur if the pesticides were not present: the cause is the pesticides, not the temperature!