Transcriptomic and Gene Expression Analysis of Chemosensory Genes from White Grubs of Hylamorpha elegans (Coleoptera: Scarabaeidae), a Subterranean Pest in South America

Abstract

Simple Summary

Hylamorpha elegans, a native Chilean scarab beetle regarded as a significant pest, feeds on economically important crops, such as red clover, ryegrass, and wheat, in its larval stage (i.e., white grubs). Traditionally, chemical control through insecticides has been used against H. elegans without success, and alternative control strategies based on ethology and the use of semiochemicals have remained elusive. Thus, chemical communication through chemosensory genes in H. elegans could represent an advance towards integrated pest management. In this study, the repertoire of chemosensory gene candidates from white grubs of H. elegans, their phylogenetic relationships, and relative gene expression have been reported for the first time.

Abstract

Olfaction and gustation processes play key roles in the life cycle of insects, such as finding and accepting food sources, oviposition sites, and mates, among other fundamental aspects of insect development. In this context, chemosensory genes found in sensory organs (e.g., antennae and maxillary palps) are crucial for understanding insect behaviour, particularly the phytophagous behaviour of insect pests that attack economically important crops. An example is the scarab beetle Hylamorpha elegans, which feeds on the roots of several crops important for livestock in its larval stage. In this study, chemosensory gene candidates of H. elegans white grubs identified through the head transcriptome and phylogenetic and tissue-biased gene expression (antennae, head without antennae, and legs) have been reported. Overall, 47 chemosensory genes were identified (2 ORs, 1 GR, 11 IRs, 9 CSPs, and 24 OBPs). Gene expression analysis revealed the predominant presence of IRs in the legs, whereas ORs and the GR were present in the heads and/or antennae. Particularly, HeleOBP9 and HeleCSP2 were significantly expressed in the head but not in the antennae or legs; these and other genes are discussed as potential targets in the context of H. elegans management.