College of Agricultural and Food Science, Zhejiang A&F University at Hangzhou, Zhejiang, China.
School of Mathematical & Natural Sciences, New College of Interdisciplinary Arts & Sciences, Arizona State University, Phoenix, AZ, USA.
Insect Mol Biol. 2019 Oct;28(5):637-648. doi: 10.1111/imb.12581. Epub 2019 Apr 4.
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.
昆虫表皮角质层上的碳氢化合物 (HCs) 不仅可减少水分流失，还可作为化学信号。细胞色素 p450 CYP4G 基因是某些昆虫中 HCs 生物合成所必需的。然而，其在黄粉虫中的功能尚不清楚。此外，宿主的 CYP4G 是否可以调节其寄生蜂的搜索行为也尚不清楚。本研究探索了 T. molitor 中 TmCYP4G122 和 CYP4G123 基因的功能。TmCYP4G122 和 CYP4G123 转录本可在所有发育阶段检测到。它们在脂肪体和腹部表皮中的表达高于肠道。在干燥胁迫下（相对湿度 < 5%），成熟幼虫中的表达水平显著高于对照（相对湿度 = 70%）。dsCYP4G122 和 dsCYP4G123 的注射导致 HCs 生物合成减少，并与对干燥的敏感性增加有关。从正常蛹中羽化出的寄生蜂 Scleroderma guani 个体对正常蛹表现出宿主偏好，而从缺乏 CYP4G122 和/或 CYP4G123 的蛹中羽化出的 S. guani 则失去了这种搜索偏好。目前的结果证实，CYP4G122 和 CYP4G123 调节 HCs 的生物合成，并调节其寄生蜂 S. guani 的嗅觉反应。
