Characterization of the proteases in the midgut of the xylophagous larvae of Oemona hirta (Coleoptera: Cerambycidae)

Abstract

The protein digestive capability of the larvae of the longhorn beetle (Oemona hirta, Coleoptera: Cerambycidae, Fabricius, 1775) was investigated. This species feeds only on wood where there is a high proportion of vascular tissue. The pH of the midgut, the major digestive organ, was alkaline and protein hydrolysis was maximal at alkaline pH. Use of specific synthetic peptide substrates showed that the major protease activities were the endopeptidases, trypsin and chymotrypsin-like activity, and the exopeptidase, leucine aminopeptidase and the pH curves corresponded to that with protein substrate. Studies using a range of serine protease inhibitors as well as specific inhibitors of metalloproteases, cysteine proteases and aspartate proteases confirmed a serine protease-based digestive system similar to earlier reports of sapwood-feeding Cerambycids. Control of these insect pests using protease inhibitors is discussed.

First evidence of a horizontally‐acquired GH‐7 cellobiohydrolase from a longhorned beetle genome

“…Considering the luminal pH of Cerambycidae larvae was found to be neutral to slightly alkaline in prior studies (Kukor & Martin, 1986; Shaw & Christeller, 2009), we opted to adjust the pH of our enzyme assays from 5.0 to 7.0. Under these conditions, we were able to detect breakdown products on TLC (as depicted in Figure 3).…”