Abstract:

Objective: Based on the phenomenon that the Anoplophora glabripennis population in Guyuan, Ningxia preferentially infests Fraxinus pennsylvanicain mixed stands with Salix matsudana, this study compares the differentiation in host adaptability between this population and the population in Qiqihar, Heilongjiang, which mainly infests Acer negundo. The purpose of this study is to reveal the physiological mechanism underlying the adaptation of the Guyuan population to F. pennsylvanica and provide important physiological basis for regional monitoring and ecological management for different geographical populations of A. glabripennis. Method: A. glabripennis adults for this experiment were collected from the two regions: the Guyuan population (G) and the Qiqihar population (Q). The two populations were mainly fed on either F. pennsylvanica or A. negundo. In this study, four treatments were set up: Guyuan population fed on F. pennsylvanica (G-Y), Guyuan population fed on A. negundo (G-F), Qiqihar population fed on A. negundo (Q-F), and Qiqihar population fed on F. pennsylvanica (Q-Y). The nutrient and secondary metabolite profiles in the bark of one-year-old branches from both host plants were analyzed. Furthermore, we measured the selective feeding amount, oviposition of two populations feeding on two host plants, non selective feeding amount, survival time of two populations feeding on a single host plant, and midgut enzyme activities (digestive, detoxification, and protective enzymes) of the beetles under the different treatments. Result: 1) There was a significant difference in the bark composition between the two host species: A. negundo had higher moisture, cellulose, soluble sugar, and sesquiterpene content than F. pennsylvanica, while F. pennsylvanica contained more flavonoids and tannins than A. negundo. There was no significant difference in starch, protein, and alkaloid content between the two. 2) Behavioral and survival of A. glabripennis exhibited distinct population specificity. The Qiqihar population had a significant preference for feeding on A. negundo, with significantly reduced survival after feeding on F. pennsylvanica, and no oviposition behavior on the host. Although the Guyuan population also preferred A. negundo, there was no significant difference in non-selective feeding amount or survival duration on the two hosts and was capable of ovipositing on F. pennsylvanica. 3) There were significantly differences in the activities of digestive enzymes, detoxifying enzymes, and protective enzymes among different treatments, which reflected the activity of midgut enzymes was co-regulated by host plant and population origin. Digestive enzyme activities were correlated with host nutrient levels, while the activities of detoxifying enzymes and protective enzymes were primarily modulated in response to host secondary metabolites. Conclusion: There is significant differentiation in their physiological adaptability to the non-preferred host, F. pennsylvanica, between the two geographic populations. Both populations maintained a strong feeding and oviposition preference for A. negundo, while only the Guyuan population has developed a notable physiological tolerance and utilization capacity for F. pennsylvanica, through its efficient detoxification enzyme system, enabling completion of feeding, survival, and reproduction on this resistant host. This differentiation likely represents local adaptive evolution under long-term selection pressure from differing host environments. The findings provide crucial physiological insights for developing region-specific monitoring and ecological management strategies for A. glabripennis.

Key words: Anoplophora glabripennis, geographic population, host selection, host adaptability, midgut enzyme