Transgenic expression of MhCHS2 dsRNA in maize confers efficient control to Monolepta hieroglyphica

In recent years, Monolepta hieroglyphica has become a destructive pest threatening food security in northeastern China, where M. hieroglyphica adults inflict substantial yield losses through feeding on young leaves, silks and sometimes on developing kernels from maize. Plant-mediated RNA interference (RNAi) has proven to be a promising tool for sustainable pest management. Thus, specific and effective RNAi target genes for M. hieroglyphica management are needed.

Using homology-based searching of the M. hieroglyphica genome, we identified two chitin synthase genes, and named them MhCHS1 and MhCHS2, respectively. MhCHS2 was found to be expressed in the midgut of M. hieroglyphica. We found that after feeding on transgenic maize expressing MhCHS2 double-stranded RNA (dsRNA) for 2 days, the expression of MhCHS2 was significantly reduced, and the formation of peritrophic membrane was inhibited in M. hieroglyphica. Notably, after feeding on maize expressing MhCHS2 dsRNA, half of M. hieroglyphica died within 4 days, with the majority succumbing by 7 days. Maize expressing MhCHS2 dsRNA exhibited a high degree of resistance to M. hieroglyphica.

These findings further validate the essential role of MhCHS2 in maintaining formation of the peritrophic membrane and ensuring organism survival in M. hieroglyphica. This study suggests that MhCHS2 might be an ideal RNAi target for pest management, and maize expressing MhCHS2 dsRNA could be a potential and effective strategy for M. hieroglyphica control. © 2026 Society of Chemical Industry.