Integrated RNA interference and RNA‐sequencing analysis of the effects of laccase2 on cuticular pigmentation and survival in Halyomorpha halys (Stål) (Hemiptera: Pentatomidae)

Abstract BACKGROUND Laccase2 is a member of the multicopper oxidase family that plays essential roles in the sclerotization and pigmentation of the insect cuticle. Previous studies have suggested RNA interference (RNAi) targeting laccase2 often resulted in high mortality in various pests. This study aims to evaluate the potential effects of laccase2 gene knockdown on a serious pest, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). RESULTS We identified, validated and characterized one laccase2 ( Hhlac2 ) gene from H. halys . Quantitative real‐time PCR results demonstrated that the expression of the Hhlac2 is tissue‐specific and changes periodically during development. The results of RNA interference revealed that injecting nymphs with the double‐stranded RNA Hhlac2 (ds Hhlac2 ) at doses ranging from 100 to 500 ng/individual significantly suppressed Hhlac2 expression, and pigmentation was not significantly inhibited until the injection dose reached more than 500 ng/individual, while the mortality rate reached over 90% at a dose of 100 ng. RNA‐sequencing analysis revealed 802 up‐regulated and 1052 down‐regulated genes in the ds Hhlac2 ‐injected group compared with control, and these unigenes were mainly enriched in terms of tyrosine metabolism, melanin biosynthesis, chitin, immunity and apoptosis. Notably, several key differentially expressed genes associated with metabolism (tyrosine metabolism, lipid metabolism and chitin metabolism) and innate immunity (Toll signaling pathway) were mainly significantly suppressed, which may influence host fitness together with phenotypic changes and increased mortality. CONCLUSION Our study elucidates the pivotal roles of Hhlac2 knockdown induces overall disorder and high mortality at the molecular and individual levels, respectively, which provide insight into biocontrol via RNAi‐based technology in heteropteran pests. © 2025 Society of Chemical Industry.