Bark beetles overcome the toxic terpenoids produced by pine trees by both detoxifying and converting them into a pheromone system. Detoxification enzymes such as cytochrome P450s, glutathione S-transferases, and carboxylesterases are involved in the ability of Dendroctonus armandi to adapt to its chemical environment. Ten genes from these three major classes of detoxification enzymes were selected to study how these enzymes help D. armandi to respond to the host defenses. The expression profile of these detoxification enzyme genes was observed in adult beetles after feeding on different types of diet. Significant differences were observed between two types of seminatural diet containing the phloem of pines, and a purely artificial diet containing five monoterpenes ((−)-α-pinene, (−)-β-pinene, (+)-3-carene, (±)-limonene, and turpentine oil) also caused differential transcript levels in the detoxification enzyme genes. The results suggest that monoterpenes enter the beetles through different routes (i.e., respiratory and digestive systems) and cause the expression of different genes in response, which might be involved in pheromone metabolism. In addition, the xenobiotic metabolism in bark beetles should be considered as a system comprising multiple detoxifying enzymes.

The ambrosia beetle Euwallacea interjectus Blandford (Coleoptera: Curculionidae: Scolytinae) has recently emerged as a pest in Chinese poplar plantations, causing significant economic losses through damage to host trees in association with its mutualistic fungus Fusarium populicola. This study evaluated the biocontrol potential of Beauveria bassiana strain B-BB-1, Serratia marcescens strain B-SM-1, its metabolite prodigiosin, and two ectoparasitic mites, Pyemotes moseri and Pyemotes zhonghuajia. B. bassiana exhibited significant lethality toward adult female E. interjectus, reduced offspring production, and inhibited F. populicola growth. S. marcescens and prodigiosin had certain lethal effects on larvae and inhibited the growth of F. populicola. Both mites effectively parasitized beetle pupae and larvae, with no significant differences in efficacy between the two species. These agents demonstrate promise for the biological control of E. interjectus, offering insights for managing ambrosia beetle infestations.