Knockdown of ecdysone receptor in male desert locusts affects relative weight of accessory glands and mating behavior. (April 2022)

• Record Type: Journal Article
• Authors: Van Lommel, Joachim; Lenaerts, Cynthia; Delgouffe, Charlotte; Vanden Broeck, Jozef
• Is Part Of: Journal of insect physiology. Volume 138(2022)
• Publication Date: 2022-04
• Subjects: 20E 20-hydroxyecdysone -- E ecdysone -- EcR ecdysone receptor -- MAG male accessory gland -- RXR retinoid-X-receptor -- USP ultraspiracle; 20-Hydroxyecdysone -- Ecdysteroid -- Insect -- Male accessory gland -- Reproduction -- Retinoid-x receptor; Insects -- Physiology -- Periodicals; Insectes -- Physiologie -- Périodiques; Insects -- Physiology; Periodicals; 571.157
• DOI: 10.1016/j.jinsphys.2022.104368
• Languages: English
• ISSNs: 0022-1910

Abstract

Graphical abstract: Highlights: In desert locust adults, male accessory glands become fully developed after 9 days. SgEcR mRNA levels are significantly higher in fat body of sexually mature males. Knockdown of SgEcR, not SgRXR, increased relative weight of male accessory glands. Knockdown of SgEcR or SgRXR caused a delay in the onset of mating behavior. In some cases Sg EcR and Sg RXR might act independently of each other. Abstract: Locusts have been known as pests of agricultural crops for thousands of years. Recently (2018–2021) the world has faced the largest swarms of desert locusts, Schistocerca gregaria, in decades and food security in large parts of Africa and Asia was under extreme pressure. There is an urgent need for the development of highly specific bio-rational pesticides to combat these pests. However, to do so, fundamental research is needed to better understand the molecular mechanisms behind key physiological processes underpinning swarm formation, such as development and reproduction. The scope of this study is to investigate the possible role(s) of the ecdysteroid receptor in the reproductive physiology of male S. gregaria . Ecdysteroids and juvenile hormones are two important classes of insect hormones and are key regulators of post-embryonic development. Ecdysteroids are best known for their role in moulting and exert their function via a heterodimer consisting of the nuclear receptors ecdysone receptor (EcR) and retinoid-X receptor (RXR). To gain insight into the role of SgEcR and/or SgRXR in the male reproductive physiology of S. gregaria we performed RNAi-induced knockdown experiments. A knockdown of SgEcR, but not SgRXR, resulted in an increased relative weight of the male accessory glands (MAG). Furthermore, the knockdown of these genes, either in combination or separately, caused a significant delay in the onset of mating behavior. Nevertheless, the MAG appeared to mature normally and the fertility of mated males was not affected. The high transcript levels of SgEcR in the fat body, especially towards the end of sexual maturation in both males and females, represent a remarkable finding since as of yet the exact role of SgEcR in this tissue in S. gregaria is unknown. Finally, our data suggest that in some cases SgEcR and SgRXR might act independently of each other. This is supported by the fact that the spatiotemporal expression profiles of SgEcR and SgRXR do not always coincide and that knockdown of SgEcR, but not SgRXR, significantly affected the relative weight of the MAG.