Improving the efficiency and safety of sentinel stink bug eggs using x-ray irradiation and other methods

Sentinel eggs used to monitor field parasitism of stink bug pests (Hemiptera: Pentatomidae) can only be deployed for a few days to avoid releasing the pest in the monitored area. Using sterile eggs removes the risk of accidental pest introduction and extends deployment time. Freezing the eggs before deployment is one common method used to sterilize sentinel eggs. However, some egg parasitoid species have lower to no parasitism on frozen eggs. In addition, frozen eggs tend to start rotting and desiccating a few days after thawing and are only suitable for parasitoid oviposition for a few days. This study explores alternative methods to produce sterile eggs: x-ray irradiation, refrigeration, and using unfertilized females. This work focuses on Bagrada hilaris (Burmeister) sentinel eggs intended to monitor parasitism by Gryon aetherium Talamas (Hymenoptera: Scelionidae), the most promising biological control candidate. However, the results could apply to other species for which frozen sentinel eggs are not a good option.