Molecular Cloning and Functional Characterization of <i>HaChi2</i> and <i>HaEchi</i> in <i>Helicoverpa armigera</i>

In the previous research, we found that compound ZQ-8 might target the chitinase of Helicoverpa armigera, thereby affecting its growth and development. However, the structural and functional characteristics of chitinase in H. armigera remain unclear, which poses difficulties in the mechanistic study of this compound. The HaChi2 (1515 bp) and HaEchi (1737 bp) coding sequences were obtained by gene cloning. Both encode stable secretory proteins of the glycoside hydrolase family 18 and are highly conserved in lepidopteran insects. Spatiotemporal expression profiling revealed their upregulation in fifth-instar larval head tissues. Functional experiments showed that dsRNA delivered by chitosan nanoparticles suppressed gene expression, and treatment with ZQ-8 significantly altered their expressions. Molecular docking predictions indicated that ZQ-8 had a stronger binding affinity and a more complex interaction network with endochitinase. These results reveal the functional differentiation of chitinases and identify endochitinase as a potential target for pest control, providing a theoretical basis for developing green strategies based on chitinase regulation.