Regulation of chitin synthesis by the juvenile hormone analogue fenoxycarb in Hyphantria cunea

Abstract

Fenoxycarb, a non-terpenoid carbamate with stomach and contact toxicity, is a promising insecticide affecting insect growth and development. However, fenoxycarb how to regulate insect digestion and absorption and chitin synthesis remains largely unclear. Here, we investigated the effects of fenoxycarb on growth, chitin synthesis, carbohydrate homeostasis, and digestive capabilities in Hyphantria cunea, a widespread agricultural and forestry pest, to clarify the action mechanism of fenoxycarb from the perspective of digestive function and carbohydrate metabolism, and confirmed that fenoxycarb significantly decreased chitin content, increased chitinase activity, and regulated the expression of genes related to chitin synthesis and degradation. Further studies showed that fenoxycarb significantly reduced glycogen content and increased glucose and trehalose contents, increased trehalase activity, and down-regulated trehalase synthesis and degradation related genes in the larvae, indicating abnormal metabolism of chitin synthesis substrates. Moreover, from the perspective of midgut digestive function, fenoxycarb significantly affected the activities of digestive enzymes in the midgut of the larvae, indicating that the larvae had digestive and absorption disorders. The findings provide a novel insight into the molecular mechanism by which fenoxycarb abnormally promotes digestive enzyme activity in the midgut and eventually interferes with insect chitin synthesis.