Laccase2-Mediated Mandibular Development Is Crucial for Larval Feeding Behavior in the Silkworm, Bombyx mori

Abstract

Simple Summary Laccase2 (Lac2) is a conserved insect gene essential for cuticle formation, pigmentation, and survival. However, its potential roles in insect feeding remain poorly understood. In this study, we investigated the function of Lac2 in the silkworm, Bombyx mori, using CRISPR/Cas9 system. Our findings suggest that loss of BmLac2 disrupted larval mandibular development, resulting in abnormal feeding behavior, reduced food intake, developmental arrest, and ultimately larval mortality. Although BmLac2 deficiency caused dopamine accumulation during the dormancy stage, dopamine levels recovered after molting and did not affect feeding motivation, suggesting that feeding impairment mainly resulted from defective mandibular development. These findings uncover a previously unrecognized role of Lac2 in regulating mandibular development and feeding ability in lepidopteran larvae.