Agrochemical Exposure Alters Insect Behavior, Survival

Even at concentrations too low to kill, exposure to widely used agrochemicals – pesticides, herbicides, and fungicides, among others – has pervasive negative impacts on insect behavior and physiology, researchers report. The findings highlight the need for more comprehensive pesticide assessments, focusing not just on lethality but also on unintended long-term ecological harm to safeguard biodiversity. Over the past decade, many reports have highlighted alarming declines in insect biodiversity worldwide, likely driven by habitat loss from farming and urbanization, climate change, and extensive pesticide use. Sublethal doses of pesticides – concentrations too low to kill – have emerged as a significant yet underexplored factor in this decline. Previous research has demonstrated how sublethal doses of agricultural chemicals can disrupt various aspects of insect biology, including metabolism, development, reproduction, immunity, and behavior. However, safety assessments of these chemicals often focus on lethal doses, and systemic experimental studies on the subtle, chronic effects of sublethal doses on non-target species remain lacking. To address this knowledge gap, Lautaro Gandara and colleagues developed a high-throughput platform using Drosophila melanogaster – a well-established insect model for toxicological assessments – to evaluate the physiological, behavioral, and fitness impacts of sublethal exposure to a suite of agrochemical molecules. Gandara et al. used a chemical library of 1,024 different agrochemicals and found that 57% of these chemicals – many without known insect-specific actions – significantly disrupted larval behavior. In addition to behavioral changes, the authors identified widespread alterations in the proteins that have phosphate groups attached to them, indicating deeper physiological impacts. Tests with chemical combinations at sublethal concentrations found widely in natural habitats were also shown to reduce D. melanogaster developmental speed and reproductive output and to compromise long-term survivability. What's more, the findings revealed that slightly elevated environmental temperatures amplified pesticide toxicity, highlighting potential risks under warming environmental conditions. Gandara et al. also found that similar behavioral disruptions were observed in other species exposed to sublethal doses, including mosquitos and butterflies, suggesting broader ecological implications.