Isolation and characterization of gut bacteria associated with the degradation of host-specific terpenoids in Pagiophloeus tsushimanus (Coleoptera: Curculionidae) larvae

Abstract

Insect intestinal bacteria play an important role in resisting defensive substances of host plants. Pagiophloeus tsushimanus (Coleoptera: Curculionidae) feeds exclusively on camphor trees (Cinnamomum camphora, Laurales: Lauraceae) in China, causing substantial economic and ecological losses. It is unclear how the larvae of P. tsushimanus outcome the main secondary metabolites of C. camphora such as D-camphor, eucalyptol, and linalool. In this study, we isolated terpenoid-degrading bacteria from the gut of P. tsushimanus larvae by using selective culture medium. Maximum likelihood phylogenetic analyses were performed with 16S rDNA sequences to identify the bacteria, and results showed ten strains belonged to four genera, including Pseudomonas, Enterobacter, Serratia, and Corynebacterium. Then, gas chromatography was employed to determine the degradability of D-camphor, eucalyptol, and linalool by the isolated strains, results showed that Z5 strain (i.e., Corynebacterium variabile, Actinomycetales: Corynebacteriaceae), F1 strain (i.e., Pseudomonas aeruginosa, Pseudomonadales: Pseudomonaceae), and A3 strain (i.e., Serratia marcescens, Enterobacterales: Enterobacteriaceae) had the highest degradation rates of D-camphor, linalool, and eucalyptol, respectively. The intestinal bacteria were capable of terpenoid degradation in vitro, which suggested that these gut bacteria associated with P. tsushimanus play an important role in overcoming host plant secondary metabolite defense, thereby facilitating the host specialization of this pest.

Penicillium-Infected Apples Benefit Larval Development of Conogethes punctiferalis via Alterations of Their Gut Bacteria Community and Gene Expression

“…Relevant studies have reported that Pantoea can exert a negative impact on aphid hosts as a pathogenic bacterium . Furthermore, infection with Asaia resulted in a shorter nymphal duration and increased adult body weight in the white-backed planthopper, while infection with Weissella played a crucial role in enhancing the adaptability of host insects. , Recent findings show that Corynebacterium from the gut of the leaf beetle Pagiophloeus tsushimanus degrades plant terpenoid secondary metabolites, enhancing insect adaptability on host plants . Moreover, Actinobacteria produce antifungal compounds, reinforcing the defensive association between these microorganisms and host insects .…”

Characterization of bacterial diversity and screening of cellulose-degrading bacteria in the gut system of Glenea cantor (Fabricius) larvae

“…For instance, P . aeruginosa had demonstrated the capability to degrade linalool, which was isolated from Pagiophloeus tsushimanus ( Qiao et al, 2023 ). Additionally, Pseudomonas sp.…”

“…may play a role in the degradation of secondary metabolites in host plant, which were associated with defense substances specific to the host plant. For instance, P. aeruginosa had demonstrated the capability to degrade linalool, which was isolated from Pagiophloeus tsushimanus (Qiao et al, 2023). Additionally, Pseudomonas sp.…”