TWO KEY VOLATILES OF CHINESE WHITE PINE (PINUS ARMANDII) (PINALES: PINACEAE: PINOIDEAE) PHLOEM RESIST INVASION BY CHINESE WHITE PINE BEETLE (DENDROCTONUS ARMANDII) (COLEOPTERA: CURCULIONIDAE: SCOLYTINAE)

Pinus armandii phloem is the key tissue in which Dendroctonus armandii live and breed. Although previous research examined the volatiles in P. armandii phloem, the dynamic changes and functions of these volatiles were never revealed. This study detected the changes in P. armandii phloem volatiles at each stage of infestation from healthy to dead trees and tested the toxicity of these volatiles against D. armandii. It revealed that (1) the weight of females was significantly greater than that of males, and females were more tolerant to host volatiles than males. (2) Limonene and myrtanol of P. armandii phloem volatiles played the key roles in resisting the invasion of D. armandii. The first increased the percentage of limonene together with other volatiles killing D. armandii in the resistant period of P. armandii, and the second synthesised myrtanol to further resist the invasion of D. armandii in the retreat period of P. armandii. These observations highlight the differences in the resistance of males and females to toxicity from the volatiles and the difference in the toxicity of different volatiles to D. armandii, revealing the defensive system of P. armandii phloem to provide a theoretical basis for the control and management of D. armandii.

Automated summary

This study detected the changes in volatile compounds in Pinus armandii phloem at each stage of infestation by Dendroctonus armandii, and revealed the defensive system of the phloem. It also found differences in the resistance of males and females to the volatiles and the toxicity of different compounds to D. armandii.