Andressa Linhares Dorneles

Queens become workers: pesticides alter caste differentiation in bees

Bees are important for the world biodiversity and economy because they provide key pollination services in forests and crops. However, pesticide use in crops has adversely affected (decreased) queen production because of increased mortality among larvae. Here, we demonstrated that in vitro-reared queens of a neotropical social bee species (Plebeia droryana) also showed high larval mortality after exposure to an organophosphate pesticide (chlorpyrifos) via larval food. Moreover, most of the surviving larvae that were destined to develop into queens became workers more likely because they ate less food than expected without pesticide skewing thus caste differentiation in this bee species. This adverse effect has not been previously reported for any other social insects, such as honeybees or bumblebees. Queens are essential for breeding and colony growth. Therefore, if our data are applicable to other pantropical social bee species across the globe, it is likely that these bees are at a serious risk of failure to form new colonies.

Toxicity of organophosphorus pesticides to the stingless bees Scaptotrigona bipunctata and Tetragonisca fiebrigi

This study estimated the toxicity of the insecticides chlorpyrifos and phosmet to the stingless bees Scaptotrigona bipunctata and Tetragonisca fiebrigi. The results showed significant differences in susceptibility between the tested species, indicating that S. bipunctata are more tolerant to chlorpyrifos than T. fiebrigi in both assays. In contrast, the two tested stingless bee species showed no significant differences in susceptibility to phosmet. Our findings indicated that the insecticides chlorpyrifos and phosmet are potentially dangerous to S. bipunctata and T. fiebrigi both topically and by ingestion. It is essential to propose measures to minimize the impact of these products on pollinators. This study is the first evaluation of the lethal effects of the insecticides chlorpyrifos and phosmet to S. bipunctata and T. fiebrigi, and it provides important support for future studies on pesticide toxicity in stingless bees.