Potenciais efeitos da exposição a fungicidas agrícolas para abelhas-sem-ferrão imaturas : conservação de polinizadores e políticas públicas

Abstract

Bees are responsible for the pollination of 80% of cultivated or wild plants, being exclusive pollinators of 65% of them. World agriculture has evolved a lot in recent years with the use of multiple technologies such as drones and artificial intelligence. However, it is still very dependent on controversial products such as pesticides. These products protect plants from pests and diseases, but can cause indirects effects on wild biodiversity from pollinators such as bees, on which many agricultural crops depend to some degree. Even the action of products considered not harmful to bees, such as fungicides and herbicides, are being questioned lately because the exposure of adult bees to the food provided to the immature ones seems to harm these insects. Therefore, this study aimed to evaluate the effects of chronic exposure, oral and topical, of agricultural fungicides Mancozebe and Pyrclostrobin on immature workers of stingless bees, using as an experimental model Scaptotrigona bipunctata. The association of the fungicide Carbendazim with the insecticide Chlorpyrifos in immature males of the same species was also evaluated. The bees were exposed to different doses of the fungicide (commercial product), calculated from the field dose indicated for citrus crops. For the active ingredient Mancozeb were used: a) 1.545 ng; b) 2.175 ng; c) 41.29 ng; d) 45.71 ng; e) 960 ng ai/μL of diet) and a control without fungicide. For Pyraclostrobin were used: a) 1.30 x 10 – 4 μl; b) 3.25 x 10 – 3 μl and c) 6.5 x 10 – 3 μl a.i./larva. The effect of the fungicide was evaluated using Kaplan-Meier and one-way Anova survival curves. Our results indicate a dose-dependent curve for the fungicide Mancozebe, and for Pyraclostrobin it was observed that the intermediate dose was 3.6 times more lethal to young bees when compared to the other doses tested. When observing the surviving bees, it is highlighted that both products caused deformations in the individuals wings and abdomen. To verify the effects of exposure to the fungicide and insecticide in males, potential changes in the genitalia were evaluated using geometric morphometry. We detected a significant difference in the shape of the exposed males genitalia. Thus, our work brings evidence of the effects caused by agricultural fungicides on immature stingless bees. Therefore, its indication as a non-harmful product to bees is questionable. In addition, it is recommended to clarify that the positive effect in combating fungal diseases can adversely affect the pollination of crops dependent on this ecosystem service.