Comparative proteotranscriptomic analysis of four carpenter moth species reveals key salivary proteins related to feeding adaptations

Salivary proteins play a crucial role in insects, facilitating nutrient acquisition and regulating complex interactions with host plants. However, most research has focused on pierce-sucking insects, leaving chewing insects, such as caterpillars largely unexplored. Carpenter moths (Cossidae) are important destructive wood bores whose larvae cause significant damage to forestry. Here, we present the first comparative morphological and proteotranscriptomic analysis of the salivary glands of four cossid species, namely Cossus cossus, Deserticossus arenicola, Streltzoviella insularis and Yakudza vicarious. Despite the conserved structure of their salivary glands, we identified a complex composition of salivary proteins involved in digestion, feeding regulation and silk production. Notably, proteins related to immunity and detoxification were enriched in sialome, indicating their essential roles in insect-plant interactions. Furthermore, our analysis revealed that cossid species with similar feeding habits exhibited convergent patterns in major protein groups and expression. Specifically, serpins were the most expressed in root feeders, while odorant-binding proteins dominated in stem feeders, likely contributing to their specific feeding preferences. Our findings highlight the essentiality of salivary proteins in feeding adaptations of carpenter moths and provide valuable insights for developing targeted pest management strategies against these wood-boring pests.