Many invertebrates develop into different color morphs in response to changes in environmental conditions. Color morphs can differ in their biology and stress tolerance including pesticide resistance, but underlying mechanisms are unclear. In this study, we found that yellow morphs (predominant in hot summer conditions) of an agricultural pest, the melon aphid Aphis gossypii, have higher levels of resistance to the commonly used pesticides imidacloprid and sulfoxaflor compared to the green morphs (predominant in cooler spring and autumn conditions), while no difference was found in morph resistance to the antibiotic/pesticide avermectin. Transcriptome analysis and biochemical assays of enzyme activities revealed no differences in metabolic processes between the two color morphs except for differentially expressed genes related to wing development. Microbiome analysis revealed that the endosymbiont Buchnera aphidicola is the dominant bacterium in both morphs, representing 86.76–99.88% of the microbiome. The yellow morph had a higher density of Buchnera compared to the green morph. When yellow morphs were treated with avermectin and antibiotics, the density of Buchnera was reduced to levels similar to the green morph, and their susceptibility to imidacloprid was simultaneously increased. These results indicate an association between resistance in the yellow morph of A. gossypii and symbiotic bacteria, providing novel insights into pesticide resistance mechanisms and the plasticity of stress adaptation.

中文翻译：

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甜瓜蚜虫黄色变体中与杀虫剂抗性有关的内共生布氏杆菌密度增加

许多无脊椎动物会响应环境条件的变化而发展为不同的颜色形态。颜色形态在生物学和压力耐受性（包括抗药性）方面可能有所不同，但潜在的机制尚不清楚。在这项研究中，我们发现一种农业病虫害甜瓜蚜虫Aphis gossypii的黄色形态（主要在炎热的夏季条件下）与绿色形态相比（对春季和秋季条件较冷），对常用农药吡虫啉和磺胺嘧啶具有较高的抗性水平，而对抗生素/农药阿维菌素的抗性没有差异。酶活性的转录组分析和生化测定表明，除了与机翼发育相关的差异表达基因外，两种颜色形态之间在代谢过程中没有差异。微生物组分析表明，内共生双歧杆菌蚜虫是两种形态的主要细菌，占微生物组的86.76–99.88％。黄色变体的布氏杆菌密度更高与绿色变体相比。当用阿维菌素和抗生素处理黄色形态时，布氏菌的密度降低到与绿色形态相似的水平，同时它们对吡虫啉的敏感性增加。这些结果表明在的黄色变形阻力之间的关联棉蚜和共生的细菌，从而提供新的见解农药抗性机制和应力适应的可塑性。