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

STERKEL, MARCOS; VOLONTÉ, MARIANO; ALBORNOZ, MAXIMILIANO G.; WULFF, JUAN PEDRO; SÁNCHEZ, MARIANA DEL HUERTO; TERÁN, PAULA MARÍA; AJMAT, MARÍA TERESA; ONS, SHEILA

JOURNAL OF EXPERIMENTAL BIOLOGY

COMPANY OF BIOLOGISTS LTD

Año: 2022 vol. 225

0022-0949

In ecdysozoan animals, moulting entails the production of anew exoskeleton and shedding of the old one during ecdysis. It isinduced by a pulse of ecdysone that regulates the expressionof different hormonal receptors and activates a peptide-mediatedsignalling cascade. In Holometabola, the peptidergic cascaderegulating ecdysis has been well described. However, very littlefunctional information regarding the neuroendocrine regulationof ecdysis is available for Hemimetabola, which displays anincomplete metamorphosis. We use Rhodnius prolixus as aconvenient experimental model to test two hypotheses: (1) the roleof neuropeptides that regulate ecdysis in Holometabola is conservedin hemimetabolous insects; and (2) the neuropeptides regulatingecdysis play a role in the regulation of female reproduction during theadult stage. The RNA interference-mediated reduction of ecdysistriggering hormone (ETH) mRNA levels in fourth-instar nymphsresulted in lethality at the expected time of ecdysis. Unlike inholometabolous insects, knockdown of eth and orcokinin isoformA (oka) did not affect oviposition in adult females, pointing to adifferent endocrine regulation of ovary maturation. However, ethknockdown prevented egg hatching. The blockage of egg hatchingappears to be a consequence of embryonic ecdysis failure. Mostof the first-instar nymphs hatched from the eggs laid by femalesinjected with dsRNA for eclosion hormone (dsEH), crustaceancardioactive peptide (dsCCAP) and dsOKA died at the expectedtime of ecdysis, indicating the crucial involvement of these genesin post-embryonic development. No phenotypes were observedupon corazonin (cz) knockdown in nymphs or adult females. Theresults are relevant for evolutionary entomology and could revealtargets for neuropeptide-based pest control tools