Abstract Laccase‐2 (Lac2) is a key phenoloxidase that catalyzes cuticular sclerotization and pigmentation, which are processes essential for insect molting and metamorphosis. Although the alternatively spliced isoform Lac2A is known to function in cuticular tanning, the physiological role of Lac2B has remained largely unresolved. Here, we identified and functionally characterized two Lac2 isoforms, LsLac2A and LsLac2B , from the cigarette beetle Lasioderma serricorne , a globally important stored‐product pest. Both isoforms are highly expressed during the pupal and eclosion stages, with transcripts localized mainly in the cuticle and wing tissues, and are transcriptionally induced by 20‐hydroxyecdysone (20E), linking their activity to endocrine regulation of development. Functional analyses revealed that LsLac2A and LsLac2B have distinct and complementary roles in molting and metamorphosis. During larval molting, LsLac2A promotes the synthesis of new cuticle by regulating genes involved in cuticular protein and chitin biosynthesis, whereas LsLac2B facilitates degradation of the old cuticle through modulation of chitinolytic and cuticular protein‐degrading genes. In the pupal stage, both isoforms influence elytral pigmentation, sclerotization, and wing morphogenesis via the coordinated regulation of wing development‐related and yellow family genes. These results reveal isoform‐specific functions of LsLac2 in cuticle renewal and morphogenesis, uncovering a novel mechanism of hormonal and genetic integration during insect development. This work provides new insight into the molecular specialization of Lac2 and identifies promising RNAi‐based targets for the sustainable control of L. serricorne .
Xu et al. (Fri,) studied this question.