Journal of Pest Science (2023) 96, 141-160

Shouyin Li, Hui Li, Jingting Wang, Cong Chen and Dejun Hao (2023)
Hormetic response and co-expression of cytochrome P450 and cuticular protein reveal the tolerance to host-specific terpenoid defences in an emerging insect pest, Pagiophloeus tsushimanus (Coleoptera: Curculionidae)
Journal of Pest Science 96 (1), 141-160
Abstract: Camphor oil (EO) and its main component (i.e. D-camphor) form specific terpenoid defences in camphor trees, Cinnamomum camphora. However, an emerging insect pest, Pagiophloeus tsushimanus (Coleoptera: Curculionidae) has recently caused serious damage to this intractable plant species, which is largely elusive. To investigate the mechanism underlying the tolerance of this weevil to host-specific terpenoid defences, we carried out the bioassays, RNA-seq, and RT-qPCR analysis based on a simulated diet environment with EO or D-camphor exposure. First, a hormetic response (a highly generalized dose–response phenomenon in toxicology) in the larval overall performance was observed in terpenoid-feeding individuals. Then, genes encoding cytochrome P450 (CYP450) and cuticular protein (CP) were induced by both EO and D-camphor exposures using comparative transcriptome, suggesting that this weevil could deploy the dual mechanism (i.e. CYP450-mediated metabolic resistance and CP-mediated cuticular resistance) to counter host terpenoid defences. Furthermore, temporal expression of CYP450 and CP genes under a low dose of D-camphor exposure indicated that there was a trade-off relationship between the inductions of CYP450 and CP genes. We speculate that the dual mechanism of terpenoid tolerance in this specialist is an essential precondition for the hormetic response in larval growth and development, ultimately contributing to its successful colonization on camphor trees. Additionally, we found a few genes related to glucose transport, juvenile hormone, and odorant binding were fine-tuned under terpenoid exposures. Taken together, our study will open new avenues for understanding insect-plant coevolutionary adaptation and developing durable control strategies for this insect pest.
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Link to article at publishers website

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pagiophloeus tsushimanus	Cinnamomum (crop)