Chlorfenapyr-based insecticide causes multiple side effects on workers of the stingless bee Partamona helleri...

Stingless bees play a crucial role in pollinating various agricultural crops, increasing yield, and natural plants, maintaining biodiversity. In recent decades, a concerning global decline in bee populations has been recorded, with pesticides being identified as a key contributing factor. Brazil, the world's largest pesticide consumer, has high diversity of stingless bees, including Partamona helleri, a species of significant ecological and agricultural importance. Chlorfenapyr is one of the most commonly used insecticides to control Phthorimaea absoluta (Lepidoptera) in tomato crops, which are frequently pollinated by P. helleri. This study investigated the effects of chlorfenapyr-based insecticide on P. helleri, establishing lethal concentrations through bioassays and revealing the insecticide's toxicity to this species. Histological analyses of the midgut of bees exposed to chlorfenapyr showed intense epithelial vacuolization, release of spherocrystals into the gut lumen, loss of regenerative cell nests, and cellular swelling, indicating irreversible structural and functional damage. Additionally, the study assessed behavioral changes in bees exposed to chlorfenapyr, recording a high level of stress through increased distance traveled and higher average velocity, suggesting sublethal effects of the pesticide. Respirometry indicated that bees exposed to chlorfenapyr exhibited a reduced respiration rate, indicating disruption of the energetic metabolism of these pollinators. These results highlight P. helleri sensitivity to chlorfenapyr and the necessity of considering the ecological and economic impacts of pesticides on the conservation of these important pollinators.