Hormonal regulation of insect reproduction and post-embryonic development

ONS SHEILA

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Sociedades de Biociencias

Insects are thedominant terrestrial life form in Earth. They affect us directly either withharmful or beneficial consequences (vectors of diseases, crop damage/ pollinators,natural predators of pests, etc.). Their evolutionary success is due toparticular strategies for development and reproduction, which have facilitatedthe colonization of a wide range of ecological niches. During post-embryonicdevelopment, insect larvae complete each molt by shedding the old cuticle, inorder to emerge as the next developmental stage. This process culminates inadults able to produce mature gametes, and is perfectly regulated by endocrine networkscomposed of lipophilic hormones and neuropeptides. The crucial involvement of neuropeptidesin development and reproduction suggests that these molecules could bepromising targets for new-generation insecticides. Given their particularcharacteristics, neuropeptidergic-targeting insecticides will offerspecies-selectivity and environmental compatibility, with practical advantagescompared to current neurotoxic insecticides. The peptidergic signaling cascade regulating ecdysisat the end of each molt has been well studied for those insect species thatundergo a complete metamorphosis (holometabolous) such as flies, moth, beetles,etc. The nodal components of this cascade are Ecdysis Triggering Hormone and EclosionHormone. However, the endocrine factors regulating ecdysis inHemimetabolous (such as kissing bugs, cockroaches, etc) has not beencharacterized to date. Strikingly, even though adults do not molt, the hormonesregulating ecdysis are expressed in this mature stage, as much in males as infemales. This suggests pleiotropic physiological roles for ecdysis hormones.Recent reports indicate that the interrelationships of hormones occurring injuvenile stages to regulate molting and ecdysis is maintained in the adultstage to regulate gametogenesis and fecundity. Hence, the members of this hormonalnetwork would be excellent candidates in the search for next-generation insectpest management strategies. In this context, our research group studieshormonal regulation in insects, focusing in the post-embryonic development andreproduction processes. Our results show for the first time that a particularfamily of neuropeptides called Orcokinin isa critical component of the regulatory network of ecdysis and reproduction ininsects. When Orcokinin geneexpression was silenced, phenotypes of arrested molting in kissing bugs andimpaired reproduction in cockroaches were observed. Furthermore, we studied thecomponents and interrelationships within this network in hemimetabolous, andfound crucial differences with holometabolous. Our recent work suggests thatOrcokinins could be excellent candidates as targets for novel insect pest managementstrategies.