Acute Thiamethoxam exposure in Apis mellifera : Absence of both stress-induced changes in mRNA splicing and synergistic effects of common fungicide and herbicide

Securing food supply for a growing population is a major challenge and heavily relies on the use of agrochemicals to maximize crop yield. Neonicotinoids are globally one of the most widely used insecticides. It is increasingly recognized, that some neonicotinoids have a negative impact on non-target organisms, including important pollinators such as the European honeybee . Toxicity of neonicotinoids may be enhanced through simultaneous exposure with additional pesticides, which could help explain, in part, the global decline of honeybee colonies. Here we examined whether exposure effects of the neonicotinoid Thiamethoxam are enhanced by the commonly used fungicide Carbendazim and the herbicide Glyphosate. We also analysed alternative splicing changes upon pesticide exposure in the honeybee. In particular, we examined transcripts of three genes: i) the stress sensor gene (, ii) the ( gene and iii) the ( gene, which are important for neuronal function. Our results showed that acute neonicotinoid exposure is not enhanced by Carbendazim, nor Glyphosate. Toxicity of the compounds did not trigger stress-induced, alternative splicing in the analysed mRNAs, thereby leaving dormant a cellular response pathway to these man-made environmental perturbations.