Xie, Y.P., Xue, J.L., Tang, X.Y., & Zhao, S.L. 2004 The Bunge Prickly-Ash tree damaged by a mealybug, Phenacoccus azaleae attracting the ladybug, Harmonia axyridis.. Scientia Silvae Sinicae 40(5): 116-122.

Notes: In this paper, the host plant (Zanthoxylum bungeanum) damaged by a mealybug (Phenacoccus azaleae) which attracts its natural enemy, the ladybug (Harmonia axyridis), was studied in Tainhang Mountain Area of Shanxi Province, China, during 1999-2001. Results showed that the percentage of the ladybug attracted to damaged fresh twigs and leaves reached 57.0%. The rate of the ladybug attracted to the extractive solution from the damaged twigs and leaves was 37.0%. The rate of the check test was 10.3%. It is suggested that the volatiles of host plant can be greatly changed by the induction of the mealybug which was attracted to twigs and leaves. Furthermore, the inductive activity released by the damaged host plant could persist for approximately two months after the mealybug stopped feeding. The inductive activities increased with the content of the damaged twigs and leaves. Through GC/MS analysis, it was found that some long chain ester compounds were distinctly increased in damaged host tree. A total of 15 compounds were observed in almost the same amount in both undamaged and damaged trees. However, the compounds were much higher in damaged host tree. Other new compounds were synthesized in the damaged host tree. These compounds might play the role of attracting the natural enemies.