Cuticular hydrocarbons form a barrier that protects terrestrial insects from water loss via the epicuticle. Lipophorin loads and transports lipids, including hydrocarbons, from one tissue to another. In some insects, the lipophorin receptor (LpR), which binds to lipophorin and accepts its lipid cargo, is essential for female fecundity because it mediates the incorporation of lipophorin by developing oocytes. However, it is unclear whether LpR is involved in the accumulation of cuticular hydrocarbons and its precise role in aphid reproduction remains unknown. We herein present the results of our molecular characterization, phylogenetic analysis, and functional annotation of the pea aphid (Acyrthosiphon pisum) LpR gene (ApLpR). This gene was transcribed throughout the A. pisum life cycle, but especially during the embryonic stage and in the abdominal cuticle. Furthermore, we optimized the RHA interference (RNAi) parameters by determining the ideal dose and duration for gene silencing in the pea aphid. We observed that the RNAi-based ApLpR suppression significantly decreased the internal and cuticular hydrocarbon contents as well as adult fecundity. Additionally, a deficiency in cuticular hydrocarbons increased the susceptibility of aphids to desiccation stress, with decreased survival rates under simulated drought conditions. Moreover, ApLpR expression levels significantly increased in response to the desiccation treatment. These results confirm that ApLpR is involved in transporting hydrocarbons and protecting aphids from desiccation stress. Furthermore, this gene is vital for aphid reproduction. Therefore, the ApLpR gene of A. pisum may be a novel RNAi target relevant for insect pest management.

中文翻译：

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Lipophorin 受体调控豌豆蚜 Ayrthosiphon pisum 表皮碳氢化合物积累和成虫繁殖力

表皮碳氢化合物形成一道屏障，保护陆生昆虫免受上表皮水分流失。Lipophorin 将脂质（包括碳氢化合物）从一个组织装载和运输到另一个组织。在一些昆虫中，与脂蛋白结合并接受其脂质货物的脂蛋白受体 (LpR) 对雌性繁殖至关重要，因为它通过发育卵母细胞介导脂蛋白的掺入。然而，尚不清楚 LpR 是否参与表皮碳氢化合物的积累，其在蚜虫繁殖中的确切作用仍然未知。我们在此展示了豌豆蚜虫 ( Acyrthosiphon pisum ) LpR 基因 ( ApLpR ) 的分子表征、系统发育分析和功能注释的结果。该基因在整个A. pisum生命周期，但尤其是在胚胎阶段和腹部角质层中。此外，我们通过确定豌豆蚜虫基因沉默的理想剂量和持续时间来优化 RHA 干扰 (RNAi) 参数。我们观察到基于 RNAi 的ApLpR抑制显着降低了内部和表皮碳氢化合物的含量以及成人的繁殖力。此外，表皮碳氢化合物的缺乏增加了蚜虫对干燥胁迫的敏感性，在模拟干旱条件下存活率降低。此外，ApLpR表达水平响应干燥处理显着增加。这些结果证实了ApLpR参与运输碳氢化合物和保护蚜虫免受干燥胁迫。此外，该基因对蚜虫繁殖至关重要。因此，ApLpR的基因A.豌豆可以是相关的害虫管理的新的RNAi靶。