Reassessment of the Role of Predators and Trissolcus basalis in Biological Control of Southern Green Stink Bug (Hemiptera: Pentatomidae) in Hawaii

The role of predators and parasitoids in biological control of the southern green stink bug, Nezara viridula (L.), in macadamia nut orchards was investigated in three field studies in Hawaii. Egg masses placed in the weeds at the orchard borders had significantly higher rates of parasitism by Trissolcus basalis (Wollaston) in 1990 and 1991 than eggs placed in the canopy of macadamia trees. Predators were more efficient at locating and destroying egg masses placed in trees than in weeds and were always more efficient than T. basalis, regardless of their location. An island-wide survey taken from July to December 1991 recovered no T. basalis, but predators were responsible for high levels of egg mortality at all locations. The importance of these findings in relationship to the commonly held view that N. viridula is under good biological control by T. basalis in Hawaii is discussed.