Tineola destroys woolen fibers but makes its own from silk
Although it is usually associated with silkworm larvae, silk spinning is rather common phenomenon in Lepidoptera. Cocoons and protective shelters are also formed by primitive species such as the clothing moth (Tineola bisselliella). However, the silk composition has been studied mostly in the more advanced species.
Fig.: Cladogram showing the basal phylogenetic position of Tineoidea relative to other Lepidoptera.
To determine the proteins that comprise T. bisselliella silk, we obtained mRNA sequences from the silk glands. We used the resulting transcriptome to establish a database for identification of short peptides from the T. bisselliella cocoon by mass spectrometry, based on their masses.
Using this method, we found 101 proteins that contained secretory signal peptides. This list included homologs of known structural proteins, like fibroins, fibrohexamerins, and sericins, together with mucins, protease inhibitors, and several enzymes. The silk gland-specific expression was confirmed for 25 of those proteins. Furthermore, T. bisselliella silk contained a surprising amount of proteases, which, however, did not originate from the silk glands but from the digestive system. We also compared some of the candidate proteins with their homologs in other lepidopteran species and determined their evolutionary relationships.
In conclusion, this study offers a detailed analysis of the silk of one of the more primitive moth species, and it presents novel candidate proteins with so far little-known functions in silk production.
Rouhová L., Kludkiewicz B., Sehadová H., Šerý M., Kučerová L., Koník P., Žurovec M. (2021) Silk of the common clothes moth, Tineola bisselliella, a cosmopolitan pest belonging to the basal ditrysian moth line. Insect Biochemistry and Molecular Biology 130 : 103527.