Effects of Gamma Irradiation on the Fecundity, Fertility, and Longevity of the Invasive Stink Bug Pest Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae)

SIMPLE SUMMARY: Controlling alien insect pests in cropping systems with no use of chemicals has always been challenging. Here, the first research studies to evaluate the use of irradiation to determine the feasibility of the sterile insect technique (SIT) approach to controlling the bagrada bug, Bagrada hilaris, are described. This work complements investigations on biological control for some of the major pentatomid pests, e.g., the brown marmorated stinkbug, the southern green stink bug, or the bagrada bug, using specific egg parasitoids. The complete sterility of males and females was reached with a minimum of 100 Gy gamma irradiation dose. This study documented how various irradiation doses impact the life history parameters of the bagrada bug, such as fertility, fecundity, and longevity. The results warrant further research to test the SIT directly on bagrada bug populations in the field or combine the SIT with a classical biological control program. ABSTRACT: The bagrada bug, Bagrada hilaris, is an invasive insect pest in the family Brassicaceae that causes economically important damage to crops. It was originally present in Asia, the Middle East, and Africa, and was reported as invasive in the southwestern part of the US, in Chile, and on a few islands in the Mediterranean Basin. In its native range, B. hilaris is controlled by several egg parasitoid species that are under consideration as potential biological control agents. This research evaluated the impact of gamma irradiation on life history parameters, e.g., the fecundity, fertility, and longevity of B. hilaris, as a critical step towards assessing the feasibility of using the sterile insect technique against this recent invasive pest. Newly emerged adults of a laboratory colony originally collected from the island of Pantelleria (Italy) were gamma-irradiated. Life history parameters were evaluated at nine different doses, ranging from 16 Gy to 140 Gy. The minimal dose to approach full sterility was 100 Gy. Irradiation up to a maximum of 140 Gy apparently did not negatively impact the longevity of the adults. Even if both genders are sensitive to irradiation, the decline in fecundity for irradiated females could be exploited to release irradiated males safely to apply the SIT in combination with classical biological control. The data presented here allow us to consider, for the first time, the irradiation of bagrada adults as a suitable and feasible technique that could contribute to guaranteeing a safe approach to control this important pest species in agro-ecosystems. More research is warranted on the competitive fitness of irradiated males to better understand mating behavior as well as elucidate the possible mechanisms of sperm selection by polyandric B. hilaris females.