Characterization of the small hive beetle transcriptome focused on the insecticide target site and RNA interference genes

Abstract

The small hive beetle (SHB), Aethina tumida, is an invasive pest species in most Northern Hemisphere countries, including Korea. SHB causes serious damage to apiaries by destroying overwintering honey bee colonies. To obtain basic information for efficient management of SHB, genes encoding conventional insecticide targets, specifically the voltage-sensitive sodium channel alpha-subunit (VSSC) and acetylcholinesterase (AChE), and RNA interference (RNAi)-related components were annotated and characterized following analysis of transcriptomes of adults and larvae. A single VSSC gene was identified but no apparent mutations associated with pyrethroid resistance were detected. Genes encoding two AChEs (AtAChE1 and AtAChE2) were identified from the SHB transcriptome. No apparent mutations associated with resistance to organophosphorus and carbamate insecticides were identified in the AtAChE1 gene, whereas the S238G mutation, originally identified from the Colorado potato beetle, was detected in the AtAChE2 gene. Native polyacrylamide electrophoresis in conjunction with western blotting revealed that AtAChE1 was the main catalytic enzyme and therefore a toxicologically more relevant target. AtAChE1 was determined to exist in both membrane-anchored and soluble forms. The main components of RNA interference (RNAi) were identified, suggesting that RNAi is likely functional in SHB and an RNAi-based approach is a feasible alternative control measure.