The identification and characterisation of a new deltamethrin resistance-associated gene, UBL40, in the diamondback moth, Plutella xylostella (L.)

• We investigated the possible role of UBL40 in deltamethrin detoxification.
• UBL40 expression was increased in response to deltamethrin treatment.
• UBL40 knockdown attenuated P. xylostella resistance to deltamethrin.
• UBL40-transfected cells increased the ability of deltamethrin detoxification.

Differential expression of ubiquitin was previously reported between Plutella xylostella strains that are resistant or susceptible to the pesticide deltamethrin (DM). This finding hinted at the potential involvement of ubiquitin in deltamethrin resistance, a theory that demanded further testing. Real-time PCR analyses revealed that one of the ubiquitin genes, UBL40, was overexpressed in the deltamethrin-resistant strain during the fourth instar. To investigate the functional relationship between this gene and deltamethrin resistance, RNA interference (RNAi) and cell transfection were utilised. UBL40 knockdown was observed to significantly reduce the level of resistance in RNAi-treated larvae after 48 h. Conversely, overexpression of UBL40 in Drosophila Kc cells conferred a degree of protection against deltamethrin. These results represent the first evidence that UBL40 plays a role in the regulation of deltamethrin resistance in P. xylostella.