The role of neuropeptides in regulating ecdysis and reproduction in the hemimetabolous insect Rhodnius prolixus

Abstract

In ecdysozoan animals, moulting entails the production of a new exoskele-ton and the shedding of the old one during ecdysis. It is induced by a pulse of ecdysone that regulates the expression of different hormonal receptors and acti-vates a peptide-mediated signalling cascade. In Holometabola, the peptidergic cascade regulating ecdysis has been well described. However, very little function-al information regarding the neuroendocrine regulation of ecdysis is available for Hemimetabola, which displays an incomplete metamorphosis. Here, we studied neuropeptides related to ecdysis regulation in the hemi-metabolous insect Rhodnius prolixus. The RNA interference-mediated reduction of ETH expression in fourth instar nymphs resulted in lethality at the expected time of ecdysis, thereby showing its crucial role in this process. Furthermore, the results revealed the involvement of ETH in the regulation of reproductive fitness. Different from holometabolous, the knockdown of ETH in adult females led to failures in egg hatching without affecting the oviposition. Most of the first instar nymphs hatched from the eggs laid by females injected with dsEH, dsCCAP and dsOKA died at the expected time of ecdysis, indicating the crucial involvement of these genes for post-embryonic development. No phenotypes were observed up-on CZ knockdown in nymphs or adult females. The conservation of the role of these neuropeptides in regulating ecdysis and reproduction throughout the class Insecta is discussed.

eIF3 subunit M regulates blood meal digestion in Rhodnius prolixus affecting ecdysis, reproduction and survival

“…The insects did not moult despite their survival being longer than the expected moulting period, indicating that the reduced survival was not due to problems during the ecdysis process. If it were the case, the nymph should die during the expected ecdysis period, as observed for Crustacean Cardioactive Peptide (Lee et al, 2013), Orcokinin A (Wulff et al, 2017) and Ecdysis Triggering Hormone knockdowns (Sterkel et al, 2022), presenting the characteristic phenotype of interrupted ecdysis (Wulff et al, 2017).…”