High host specificity in Encarsia diaspidicola (Hymenoptera: Aphelinidae), a biological control candidate against the white peach scale in Hawaii

Abstract

Pre-introductory host specificity tests were performed with Encarsia diaspidicola, a biological control candidate against the invasive white peach scale, Pseudaulacaspis pentagona. False oleander scale, P. cockerelli, coconut scale, Aspidiotus destructor, cycad scale, Aulacaspis yasumatsui, greenhouse whitefly, Trialeurodes vaporariorum, green scale, Coccus viridis, and long-tailed mealybug, Pseudococcus longispinus were tested in quarantine using traditional no-choice tests and examined for wasp emergence. The Hawaiian endemic palm scale, Colobopyga pritchardiae was also tested using no-choice tests and evaluated using species-specific molecular markers. All tests used unexposed non-target cohorts and no-choice exposure of white peach scale to the parasitoid as controls. None of the non-target exotic species yielded wasp emergence, and exposure to wasps had no effect on the mortality of the non-target species examined. Molecular tests with the endemic palm scale showed no evidence of parasitism by E. diaspidicola. These results strongly support that E. diaspidicola has a narrow host range and that its release in Hawaii will have negligible risk of non-target effects.