Response of a Predatory Insect, Chrysopa sinica, toward the Volatiles of Persimmon Trees Infested with the Herbivore, Japanese Wax Scale

Abstract

A predatory insect, Chrysopa sinica Tiedet (Neuroptera: Chrysopidae), and its taxis behavior were investigated in a tritrophic system that included a herbivore, Ceroplastes japonicus Green (Hemiptera: Coccidae), and a host plant, persimmon tree, Diospyros kaki L. (Ebenaceae). The results showed that this predator was attracted to the volatile compounds of persimmon trees that were infested with C. japonicus; however, the attraction varied with the growth season of the trees and the development stage of the wax scale. The strongest attraction occurred in the autumn and not in the late spring or summer. For the four time periods considered throughout the day, the most significant attraction rates were found at midnight and the early afternoon. The results indicated that the transformation of the chemical compositions of the volatiles of the persimmon tree might drive the taxis response of the predator in the three studied seasons. We mainly found differences in terpenoid emissions and propose that these compounds play a key part in the observed differences in attractiveness.