Knockdown of a chemosensory protein disrupts soil-guided behavior of a subterranean larval pest.

Abstract

In recent years, RNA interference (RNAi) has become a widely studied tool for the functional analysis of genes and more recently, for pest control. Hylamorpha elegans (Coleoptera: Scarabaeidae) is a beetle endemic to Chile, considered an important pest during its larval stage as white grubs, feeding on organic matter (OM) and crop roots (e.g., wheat and red clover). Its control is limited due to its subterranean behavior. Thus, studying a chemosensory system as a fundamental part of the transport and recognition of chemicals from the environment could provide new targets for the knowledge and control of this beetle. Recently, chemosensory genes have been identified for H. elegans white grubs, and a chemosensory protein (CSP) was selected. This study aimed to evaluate the functional role of a highly expressed CSP in the subterranean behavior of white grubs. For this purpose, food preference assays were performed and standardized. Afterward, double-stranded RNA (dsRNA) was synthesized based on a selected CSP. A chosen preference assay was conducted using white grubs treated with dsRNA. Findings showed that white grubs prefer peat with high OM over red clover roots. Additionally, the CSP gene is upregulated when OM content increases. Finally, the knockdown of the CSP led to a disruption in soil-guided behavior. This protein may represent a novel target to be studied in the frame of management strategies for H. elegans.