Adventive Gryon aetherium Talamas (Hymenoptera, Scelionidae) associated with eggs of Bagrada hilaris (Burmeister) (Hemiptera, Pentatomidae) in the USA

Abstract

Bagrada bug, Bagrada hilaris (Burmeister) (Hemiptera, Pentatomidae), has become a major pest of cole crops (cabbage, broccoli, cauliflower, kale) in California since its arrival in 2008. In this study we documented parasitism of B. hilaris eggs at a highly infested site in northern California by deploying sentinel B. hilaris eggs and collecting naturally-laid B. hilaris eggs in the soil. Two parasitoids, Gryon aetherium Talamas (Hymenoptera, Scelionidae) and Ooencyrtus californicus Girault (Hymenoptera, Encyrtidae), emerged from sentinel eggs, but only G. aetherium was documented attacking eggs in the soil. Gryon aetherium is currently being assessed as a classical biological control agent for B. hilaris in California, and mating experiments showed that crosses between G. aetherium from Pakistan and California yielded viable female offspring. This report marks the first known record of G. aetherium in the USA, and further work should be conducted to assess the potential of this parasitoid for biological control of B. hilaris.