How is the reaction of the Apis mellifera brain to a sublethal dose of thiamethoxam?

Abstract

Pollination by Apis mellifera is extremely important ecologically as well as in agriculture, playing also an important role in beekeeping. However, some xenobiotic compounds, such as thiamethoxam introduced in agro ecosystems, are toxic to bees and have caused mass disappearance of colonies in several countries, risking the process of pollination and thus causing an environmental imbalance. Thiamethoxam is extremely active in the insect nervous system, acting as an agonist of acetylcholine. Therefore, this study aims to evaluate the acute oral toxicity of thiamethoxam to africanized Apis mellifera and investigate how the brain of these insects reacts to the intoxication by sublethal doses of tiametoxam. For this, will be investigated possible changes in synaptic pattern by immunolocalization of the protein synapsin, and spatial distribution of the proteins present in the brain by Maldi-imaging technique. These techniques, together, will provide information about which brain structures are affected by tiametoxam, which suggest possible physiological and behavioral consequences that such exposure may cause the insect. Through the obtained results we intend to elucidate the neurotoxic effect of the insecticide in order to understand how thiamethoxam can change the physiology of bees. On the other hand the observations of the effect of this insecticide on the nervous system of the bees may provide subsidies to observe behavioral changes that affect the intra-colonial. So, this study can contribute to clarify whether such insecticides would be among the causes of the "syndrome of the disappearance of bees" (Colony Collapse Disorder - CCD) currently worrying beekeepers and farmers. (AU)