Functional analysis of adipokinetic hormone signaling in reproductive diapause of Coccinella septempunctata

Abstract

BACKGROUNDThe ladybeetle, Coccinella septempunctata, an important predator, is widely used to control aphids, whiteflies, mites, thrips, and lepidopteran pests. Diapause control technology is the key to extend C. septempunctata shelf‐life and commercialization. Lipid accumulation is a major feature of reproductive diapause, but the function of AKH signaling as a regulator of lipid mobilization in reproductive diapause remains unclear. This study aimed to identify and characterize AKH and AKHR genes, and clarify their functions in reproductive diapause.RESULTSThe relative expression levels of CsAKH and CsAKHR were the highest in the head and fat body, respectively, and significantly decreased under diapause conditions, both in developmental stages and tissues (head, midgut, fat body, and ovary). Furthermore, CsAKH and CsAKHR expression was increased significantly after JH injection, but CsMet silencing significantly inhibited CsAKH and CsAKHR expression, while CsMet knockdown blocked the induction effect of JH. CsAKH and CsAKHR knockdown significantly reduced water content, increased lipid storage, promoted the expression of genes related to lipid synthesis, meanwhile significantly blocked ovarian development, and induced forkhead box O (FOXO) gene expression in C. septempuctata under reproduction conditions. In contrast, injection of AKH peptide significantly inhibited FOXO expression, reduced lipid storage, and increased water content in C. septempuctata under diapause conditions.CONCLUSIONThese results indicate that CsAKH and CsAKHR are involved in the regulation of lipid accumulation and ovarian development during diapause in C. septempuctata, and provide a promising target for manipulating C. septempunctata diapause.This article is protected by copyright. All rights reserved.