Improving the Efficiency and Safety of Sentinel Stink Bug Eggs Using X-rays

Area of Science:

• Agricultural Entomology
• Biological Control
• Insect Pest Management

Background:

• Sentinel eggs are crucial for monitoring field parasitism of stink bugs (Hemiptera: Pentatomidae).
• Current methods using sentinel eggs have limitations, such as short deployment times and potential pest release.
• Freezing sentinel eggs, a common sterilization method, reduces parasitism rates by certain parasitoid species, like Gryon aetherium (Hymenoptera: Scelionidae).

Purpose of the Study:

• To evaluate X-ray irradiation as a sterilization method for Bagrada hilaris sentinel eggs.
• To assess the efficacy of irradiated eggs for monitoring parasitism by Gryon aetherium and Ooencyrtus californicus (Hymenoptera: Encyrtidae).
• To determine if X-ray irradiation impacts the development and host-selection behavior of key egg parasitoids.

Main Methods:

• Bagrada hilaris eggs were exposed to varying doses of X-ray irradiation.
• Sterility was assessed at different irradiation doses, with 10 Gy inducing 100% sterility.
• Parasitism levels and parasitoid development on irradiated eggs were compared to fresh eggs, and Gryon aetherium host preference was tested.

Main Results:

• X-ray irradiation at doses as low as 10 Gy achieved 100% sterility in B. hilaris eggs.
• Irradiated eggs supported normal development of Gryon aetherium and Ooencyrtus californicus.
• Parasitism rates on irradiated eggs were comparable to fresh eggs for up to seven days, and Gryon aetherium showed no preference for non-irradiated eggs.

Conclusions:

• X-ray irradiation is a viable and effective alternative to freezing for sterilizing sentinel eggs.
• This method provides safe and reliable sentinel eggs for monitoring B. hilaris parasitism by key biological control agents.
• The findings suggest X-ray irradiation can be applied to other sentinel egg systems for pest monitoring.