| Abstrakt: |
Bagrada bug, Bagrada hilaris(Burmeister) (Hemiptera: Pentatomidae), is an invasive pest of cruciferous crops. The parasitoid Gryon aetheriumTalamas (Hymenoptera: Scelionidae) is a promising biological control agent for B. hilarisbecause it can forage in the soil where B. hilarisdeposits most of its eggs. In this study, we assessed parasitism by G. aetheriumon B. hilariseggs in situ in northcentral California, including the Salinas Valley where most cruciferous crops in the United States are grown. Parasitism was documented by leaving soil-filled trays under infested plants for 7–14 days, then removing eggs and holding them for emergence of parasitoids. Gryon aetheriumaccounted for over 99% of emerged parasitoids, and occurred at 11 of the 12 sampled sites. Of the 17,729 and 31,759 B. hilariseggs collected in 2021 and 2022, 1,518 (8.84%) and 2,654 (8.36%) were parasitized by G. aetherium, respectively. Parasitism rates were generally higher inland and ranged from 3.64% to 44.93% in 2021 and from 1.01% to 23.04% in 2022, and never exceeded 15% on any sample dates at several coastal sites in the Salinas Valley. Discovery efficiency (a measure of the ability of parasitoids to locate egg patches) reached 80% or higher at all but 1 site, but exploitation efficiency (a measure of the ability of parasitoids to exploit the egg patch after it has been discovered) was generally <20%, suggesting that G. aetheriumcan locate egg patches efficiently but is less efficient at finding eggs within patches. |
