Disruption of egg and nymph development via RNAi-mediated Glutamine: fructose-6-phosphate aminotransferase knockdown in <i>Locusta migratoria</i>: A promising strategy for pest management.

Glutamine: fructose-6-phosphate aminotransferase (GFAT) is the first rate-limiting enzyme in the hexosamine biosynthetic pathway, which plays a crucial role in various biological processes, including chitin metabolism in insects. <i>Locusta migratoria</i>, a widespread and highly destructive agricultural pest, poses a significant threat due to its rapid reproduction and long-distance migration. In this study, we identified and characterized <i>LmGFAT</i> as a key regulator of locust development. The expression pattern showed that <i>LmGFAT</i> was highly expressed during the early and late stages of embryogenesis. Knockdown of <i>LmGFAT</i> by microinjection resulted in a 95 % egg mortality rate compared to ds<i>GFP</i>-injected embryos. <i>LmGFAT</i> was mainly distributed in the wing pad, integument, midgut and gastric caeca among the different tissues of fifth-instar nymphs. During development from the 4th and 5th nymphal instars, the expression of <i>LmGFAT</i> reached maximal levels after ecdysis. In fifth-instar nymphs injected with ds<i>LmGFAT</i>, <i>LmGFAT</i> expression was significantly suppressed, leading to a marked reduction in cuticular chitin content. Consequently, the nymphs were unable to successfully molt, failing to shed their old cuticle completely, which ultimately resulted in mortality. Furthermore, RNA interference (RNAi) efficiency analysis showed that naked ds<i>LmGFAT</i> reduced <i>LmGFAT</i> expression by over 63 %, resulting in 70 % mortality. Notably, chitosan-complexed ds<i>LmGFAT</i> (Cs/ds<i>LmGFAT</i>) significantly enhanced RNAi efficiency, leading to a nearly 90 % mortality. Collectively, our findings establish <i>LmGFAT</i> as an essential gene for egg and nymph development in <i>L. migratoria</i>. Moreover, the enhanced RNAi efficacy achieved through chitosan-mediated dsRNA delivery highlights its potential as an innovative approach for locust population control by targeting critical developmental pathways.