Hydrocarbons (HCs) present on the epicuticle of terrestrial insects are not only used to reduce water loss but are also used as chemical signals. The cytochrome p450 CYP4G gene is essential for HC biosynthesis in some insects. However, its function in Tenebrio molitor is unknown. Moreover, it is not yet known whether CYP4G of a host can modulate the searching behaviours of its parasitoid. Here, we explore the function of the TmCYP4G122 and CYP4G123 genes in T. molitor. The TmCYP4G122 and CYP4G123 transcripts could be detected in all developmental stages. Their expression was higher in the fat body and abdominal cuticle than in the gut. Their transcript levels in mature larvae under desiccation stress [relative humidity (RH) < 5%] was significantly higher than that in the control (RH = 70%). Injection of dsCYP4G122 and dsCYP4G123 caused a reduction in HC biosynthesis and was associated with increased susceptibility to desiccation. Individuals of the parasitoid Scleroderma guani that emerged from mealworm pupae showed host preference for normal pupae whereas S. guani that emerged from pupae lacking CYP4G122 or/and CYP4G123 lost this searching preference. The current results confirm that CYP4G122 and CYP4G123 regulate the biosynthesis of HCs and modulate the olfactory response of its parasitoid S. guani.

中文翻译：

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黄粉虫中由TmCYP4G122和TmCYP4G123催化的碳氢化合物可调节拟寄生虫硬皮鸟粪的嗅觉反应。

存在于陆地昆虫表皮上的碳氢化合物（HCs）不仅用于减少水分流失，而且还用作化学信号。细胞色素p450 CYP4G基因对于某些昆虫的HC生物合成至关重要。然而，其在黄粉虫中的功能尚不清楚。而且，还不知道宿主的CYP4G是否可以调节其寄生性寄生虫的搜索行为。在这里，我们探索T.CYP4G122和CYP4G123基因在T. molitor中的功能。该TmCYP4G122和CYP4G123可以在所有发育阶段检测到转录本。它们在脂肪和腹部表皮中的表达高于肠道。在干燥胁迫下[相对湿度（RH）<5％]，它们在成熟幼虫中的转录水平显着高于对照（RH = 70％）。注射ds CYP4G122和ds CYP4G123导致HC生物合成减少，并且与干燥敏感性增加相关。从粉虫worm中出现的寄生虫硬皮鸟粪的个体表现出对正常p的寄主偏好，而从p中出现的沙门氏菌缺乏CYP4G122或/和CYP4G123失去了此搜索偏好。目前的结果证实CYP4G122和CYP4G123调节HCs的生物合成，并调节其寄生性鸟粪链球菌的嗅觉反应。