Toxicity of chlorpyrifos, cyflumetofen, and difenoconazole on Tetragonisca angustula (Latreille, 1811) under laboratory conditions

Bees can be contaminated with pesticides in agricultural areas during foraging; however, effects of pesticides on stingless bee species are not well studies. Thus, this research evaluated the toxic effects of the insecticide chlorpyrifos, acaricide cyflumetofen and the fungicide difenoconazole for Tetragonisca angustula exposed in different means of exposure to pesticides under laboratory conditions. For this, pesticides were applied to bees through three modes of exposure: ingestion, treated surface and topical application based on the doses recommended by the manufacturers (chlorpyrifos—100 mL / 100 L of water; cyflumetofen—40 mL / 100 L of water; difenoconazole—20 mL / 100 L of water). After exposure, bees were evaluated within one to 96 h for survival and effects on behavior. In bees exposed to contaminated food up to 96 h of product exposure, survival was 0%, 96% and 76% respectively for chlorpyrifos, cyflumetofen and difenoconazole. In the treatment of contact with treated surfaces, bee survival was 0%, 100%, and 42%, whereas for topical application, survival rates were 0%, 88%, and 100% for the same pesticides. Regardless of the lethal effects of cyflumetofen and difenoconazole, the bees that survived showed significant behavioral changes, such as agitation, constant flapping and self-cleaning. Chlorpyrifos was extremely toxic to T . angustula in the three exposure means evaluated, whereas, bees exposed to difenoconazole were less tolerant when applied via ingestion and on treated surface. Cyflumetofen had a low effect on bee survival, however, all pesticides caused changes in the behavior of bees.