Disruption of carboxylesterase DaEST3 reduces tolerance to host allelochemicals in Dendroctonus armandi

Bark beetles mainly rely on detoxification enzymes to overcome the defensive oleoresin terpenes of their host. Insect Carboxylesterases (CarEs) play an important role in the detoxification of plant allelochemicals and insecticides. Nevertheless, the functions of specific CarE genes in metabolization of exogenous substances are still unclear in the Chinese white pine beetle, Dendroctonus armandi. In this study, we sequenced and characterized the full-length cDNAs of six CarE (DaEST1-DaEST6) genes from D. armandi. Spatiotemporal expression profiling showed that the expression of DaEST1, DaEST3 and DaEST4 in D. armandi was higher in the larval and adult stages, and these genes mainly expressed in fat body, Malpighian tubules and midgut. Moreover, the expression of DaEST1, DaEST3 and DaEST4 was significantly induced after treatment with four terpenoids. Importantly, disruption of DaEST3 significantly inhibited the CarE activity and reduced the tolerance of adults to host allelochemicals in D. armandi. Additionally, treatment with triphenyl phosphate to adults also reduced the tolerance after terpenoids exposure, which resulted in a significant decrease of CarE activity, leading to a significant improvement of mortality in D. armandi. These results indicate that DaEST3 plays an important role in determining the tolerance to host allelochemicals in D. armandi, which might be of great significance in developing new therapeutic methods to pest control.

Automated summary

Bark beetles rely on detoxification enzymes to overcome host defensive oleoresin terpenes. Insect Carboxylesterases (CarEs) are important for detoxification of plant allelochemicals and insecticides. However, the specific functions of CarE genes in metabolizing exogenous substances in the Chinese white pine beetle are still unclear. This study sequenced and characterized six CarE genes from D. armandi and found that DaEST3 plays a significant role in determining the tolerance to host allelochemicals in this beetle.