Analysis of the effects of the pesticide clothianidin on the midgut and tubules of Malpighi from Scaptotrigona postica Latreille, 1807 (Hymenoptera, Apidae)

In Brazil, Scaptotrigona postica bees are important pollinators of native and cultivated plants. However, due to agricultural intensification and the indiscriminate use of pesticides, the populations of these pollinators are being reduced to levels that harm ecosystem pollination services. In Brazil, different groups of pesticides are used, including clothianidin, a systemic insecticide whose residues can be found in pollen and nectar, which is a route of exposure to bees. In this context, the objective of this study was to evaluate possible morphological changes in the midgut and Malpighi tubules of stingless bees S. postica, due to chronic exposure to a sublethal concentration of clothianidin (0.0000118ng ia / μL of diet), for 8 days. For this, the morphological analyzes were performed through sections of the organs, which were subjected to histology and morphology techniques. The analyzes were performed taking into account the loss of cytoplasmic material, brush border, elimination of cells to the lumen, pycnosis, loss of regenerative cell nests, cellular swelling, apocrine secretion and spherocrystals. For each observed change, a pre-established score value was used, which represents the severity of the changes in the organs. The results showed that chronic exposure to clothianidin was able to cause significant morphological changes in both organs and observed times, with the exception of apocrine secretion and spherocrystals. Such results are essential as they provide important data on the toxicity of this insecticide at the cellular and tissue level in stingless bees.