Hormonal Signals & Gravity Cues: How Insects Master Metamorphosis?

Abstract :

The DEB team investigates how Insects regulate the timing and allocation of resources from development to reproduction through the juvenile to adult metamorphic transition. Two key factors tightly control this process: (1) physiological and molecular mechanisms that govern the precise timing of ecdysone secretion—the sole steroid hormone existing in all insects that triggers metamorphosis—and (2) behavioral adaptations that ensure its successful execution. In this seminar, I will present two aspects of this regulation. First, I will discuss our study (currently under revision) on specialized filopodia structures, which we term hormonemes, and their role in ecdysone secretion. We found that hormonemes are essential for steroid hormone exocytosis, forming a polarized secretion mechanism that fine-tunes hormone timing by adjusting their length and density. This study suggests a conserved role for membrane projections in steroid hormone release. Second, I will introduce our BIGS (Bees and Insects: Gravitational Studies) project within the EXPLOR’AE program. Our preliminary findings indicate that insects, in a species-specific manner, systematically orient their puparium in a precise position to undergo metamorphosis. Interestingly, honeybees also exhibit a case-dependent orientation. This raises fundamental questions about how gravity influences the metamorphic developmental processes across species. By bridging molecular, behavioral, and ecological perspectives, we aim to uncover whether insects and, more specifically, bees could adapt their metamorphic development to nonterrestrial gravitational conditions.

The seminar can also be followed via ZOOM: https://inrae-fr.zoom.us/j/4292208801