Lyonet's gland of the tomato fruitworm, Helicoverpa zea (Lepidoptera: Noctuidae)

The Lyonet's gland is a widespread accessory labial gland in Lepidoptera. Although its function is ambiguous, the Lyonet's gland arguably plays an important role in silk production. Our knowledge of the Lyonet's gland in heliothine species is extremely limited; it is reportedly missing from Helicoverpa armigera and Heliothis virescens, whereas it is reportedly reduced in size in Helicoverpa zea. Using confocal microscopy and brightfield imaging, we show that the Lyonet's gland in Helicoverpa zea is present and the size is relatively enlarged relative to other lepidopterans. We also examined whether glucose oxidase, an abundant enzyme found in labial salivary gland is also present in the extracts of Lyonet's gland, but we found no evidence of that. Based on the size and accessibility of the Lyonet's gland, future studies should include transcriptomic and proteomics studies in H. zea to provide evidence for potential functions.