Transcriptomic Analysis of the Head Reveals Molecular Mechanisms Underlying Topical Imidacloprid Effects on Africanized Apis mellifera Forager Bees

The global decline of bees has raised significant concerns due to their crucial role in agroecosystems, rendering their diminishment a potential predisposing factor for a worldwide crisis in the agri-food sector and ecosystems. Multiple factors contribute to the decline of pollinator species, including land-use alterations with monoculture expansion, intensive agricultural practices, and the use of systemic pesticides, such as neonicotinoids, which can impact non-target organisms, including bees. This study aimed to evaluate the effect of the neonicotinoid imidacloprid on the gene expression, through contact bioassays (at lethal and sublethal doses) on Africanized Apis mellifera forager bees, analysing the transcriptome of their heads. The results revealed differential gene expression after one and four hours of imidacloprid exposure. Differentially expressed genes (DEGs) were categorized based on gene ontology, revealing alterations in critical biological processes, molecular functions, and cellular components. These changes were associated with immune response, stress, neurotoxicity, and other vital functions. The study identified genes associated with major royal jelly proteins and Yellow proteins, which play significant roles in bee physiology, development, and behavior. Furthermore, an impact on odorant-binding proteins was observed, suggesting altered sensory abilities in bees. These findings contribute to a deeper comprehension of the molecular mechanisms underlying the effects of imidacloprid on honeybees. The study highlights the importance of considering sublethal pesticide effects and their potential long-term consequences on bee populations and ecosystem functioning.

全球蜜蜂种群衰退已引发广泛担忧，因其在农业生态系统中扮演着不可或缺的核心角色，故而蜜蜂数量减少可能成为全球农业食品领域与生态系统危机的潜在诱因。传粉物种数量下降受多种因素驱动，包括土地利用格局改变伴随的单一作物种植扩张、集约化农业生产方式，以及新烟碱类杀虫剂（neonicotinoids）的使用——这类系统性药剂可对包括蜜蜂在内的非靶标生物产生影响。本研究通过接触生物测定法（设置致死与亚致死剂量），对非洲化西方蜜蜂（Africanized Apis mellifera）的采集蜂开展试验，旨在评估新烟碱类杀虫剂吡虫啉（imidacloprid）对其基因表达的影响，并对其头部转录组（transcriptome）进行分析。结果显示，在暴露于吡虫啉1小时与4小时后，蜜蜂体内出现了差异基因表达现象。研究人员基于基因本体（Gene Ontology，GO）对差异表达基因（differentially expressed genes，DEGs）进行功能分类，发现其关键生物学过程、分子功能及细胞组分均发生显著改变。这些变化与免疫应答、应激反应、神经毒性及其他重要生理功能密切相关。本研究还鉴定出与主要蜂王浆蛋白（major royal jelly proteins）及Yellow蛋白相关的基因，这类蛋白在蜜蜂生理、发育与行为调控中发挥关键作用。此外，研究观察到气味结合蛋白（odorant-binding proteins）的表达受到扰动，提示蜜蜂的感官能力可能出现异常。上述研究结果有助于更深入地阐明吡虫啉影响蜜蜂的分子机制。本研究同时强调，在评估农药的生态风险时，需充分考虑杀虫剂的亚致死效应及其对蜂群种群与生态系统功能的潜在长期影响。