Influence of triflumezopyrim and triadimefon co-exposure on enzymatic activity and gene expression changes in honey bees (Apis mellifera L.)

Abstract

Pollination insects frequently encounter complex mixtures of pesticides within agricultural ecosystems. However, current risk assessments for pesticides focus primarily on single agents, failing to reflect real-world conditions. Mesoionic insecticide triflumezopyrim (TFM) and triazole fungicide triadimefon (TAD) are two compounds often detected together in the environment, raising concerns over their combined toxic effects on pollinators. In this context, our study aimed to explore the enzymatic and transcriptional responses in the honey bee (Apis mellifera L.) when exposed to a mixture of TFM and TAD. Our findings revealed that co-exposure to these two pesticides induced acute synergistic toxicity in A. mellifera. Furthermore, significant alterations were observed in the levels of MDA, AChE, GST, and trypsin, along with the expression of four genes (abaecin, CRBXase, CYP6AS14, and CYP306A1) linked to oxidative stress, neural function, detoxification pathways, digestion, and immune competence. Additionally, both pesticides were found to modify the molecular conformation of CAT and AChE, thereby influencing their enzymatic activities. These results underscored the biochemical and molecular toxicities resulting from the combined action of TFM and TAD on A. mellifera, offering critical insights into the ecological impact of pesticide mixtures on pollinators. Importantly, the co-presence of TFM and TAD might exacerbate physiological damage in A. mellifera, likely due to their interactive effects. Collectively, this study represented a substantial advancement in comprehending the toxicological impacts of commonly used agricultural pesticides and provided valuable foundations for developing effective strategies to mitigate their harmful effects on pollination insects.