Original paper

Three CYP4G genes contribute to cuticular penetration resistance by participating in hydrocarbon biosynthesis in Aethina tumida

Wu, Lixian; Mei, Shiqiong; Xu, Yajing; Liu, Fang; Zeng, Xinnian; Zhao, Hongxia

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Entomologia Generalis Volume 45 Number 1 (2025), p. 295 - 304

published: Feb 26, 2025
published online: Feb 6, 2025
manuscript accepted: Jan 3, 2025
final revised version received: Sep 28, 2024
manuscript revision requested: Aug 9, 2024
manuscript received: Aug 7, 2024

DOI: 10.1127/entomologia/2024/2918

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Abstract

Insect cuticle hydrocarbons (CHCs) are critical in regulating desiccation tolerance and insecticide penetration. The last step of CHC biosynthesis is known to be catalyzed by an insect-specific cytochrome P450 of the 4G subfamily (CYP4G). Some insect species have multiple (more than two) CYP4G genes, but their functions are not well understood. In this study, three genes (CYP4G277, CYP4G278, and CYP4G279) were identified in the small hive beetle Aethina tumida. Then we analyzed and compared the sequence similarity, expression patterns, and function in CHC biosynthesis of the three CYP4G genes. RT-qPCR showed that CYP4G277, CYP4G278, and CYP4G279 were highly expressed in the embryonic, larval, and adult stages, respectively, with specific localization in larval integument or adult abdomen. Silencing each of the CYP4G genes through RNA interference (RNAi) led to a decrease in CHC contents, in n-alkanes and alkenes for CYP4G279, but only in n-alkanes for CYP4G277 and CYP4G278. Furthermore, knockdown of the three genes increased beetle susceptibility to desiccation and insecticides. Our studies suggest that these three CYP4G genes contribute to CHC biosynthesis and protect beetles from water loss and insecticide penetration. Notably, the observation that CYP4G279 RNAi is highly lethal suggests that CYP4G279 may serve as a candidate target for developing insecticidal agents to control small hive beetles.

Keywords

P450 • RNA interference • RNAi • desiccation • small hive beetle • insect cuticle hydrocarbon