Sterile but sexy: assessing the mating competitiveness of irradiated Bagrada hilaris males for the development of a Sterile Insect Technique

Authors: MAINARDI, CHIARA - University Of Rome; PECCERILLO, CHIARA - University Of Trento, Italy; MUSMECI, SERGIO - Enea Casaccia Research Center; PAOLINI, ALESSANDRA - Bbca-Onlus, Italy; SFORZA, RENE - European Biological Control Laboratory (EBCL); CEMMI, ALESSIA - Enea Casaccia Research Center; DI SARCINA, IARA - Enea Casaccia Research Center; ANFORA, GIANFRANCO - University Of Trento, Italy; PORRETTA, DANIELE - University Of Rome; CRISTOFARO, MASSIMO - Bbca-Onlus, Italy

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2025
Publication Date: 4/7/2025
Citation: Mainardi, C.E., Peccerillo, C., Musmeci, S., Paolini, A., Sforza, R., Cemmi, A., Di Sarcina, I., Anfora, G., Porretta, D., Cristofaro, M. 2025. Sterile but sexy: assessing the mating competitiveness of irradiated Bagrada hilaris males for the development of a Sterile Insect Technique. Insects. 16: 391. https://doi.org/10.3390/insects16040391.
DOI: https://doi.org/10.3390/insects16040391

Interpretive Summary: Invasive agricultural insects cause severe economic losses worldwide due to their feeding activity on crops. The painted bug Bagrada hilaris (Hemiptera: Pentatomidae) is currently controlled almost exclusively through the spraying of synthetic insecticides. Among the possible least-toxic alternative approaches, one possible solution is the Sterile Insect Technique (SIT), which consists in sterilizing males by gamma irradiation and releasing them into the field so that they mate with wild females, thereby reducing the sustainability of the target population. In this study, we analyzed the sexual behavior of irradiated and non-irradiated males to test whether sterile males remain competitive with their fertile counterparts. After identifying the optimal irradiation dose, we compared the mating duration of treated males under different conditions. The results showed that irradiation does not affect the sexual performance of males; in fact, they appear to perform better than non-irradiated males. These data indicate that SIT could be an effective tool for controlling B. hilaris, helping to reduce pesticide use and promote more sustainable management of this invasive species.

Technical Abstract: Bagrada hilaris (known as painted bug) is a pest native to India, Southeast Asia, and Middle and central Africa and was reported as invasive in the southwestern USA, Hawaii, Mexico, South America, and two Mediterranean islands. The feeding activity results in extensive damage to economically important Brassicaceae crops. Among sustainable alternatives to synthetic pesticides, the Sterile Insect Technique (SIT) is considered a promising strategy because it relies on the release of competitive sterile males that can reduce the pest reproduction. In this study, the efficacy of different doses of gamma irradiation (60, 80, and 100 Gy) was evaluated to identify the treatment that would ensure high sterility without compromising the competitiveness of the treated males. Observational tests showed that the doses of 60 Gy and 80 Gy showed no difference in mating times compared to non-irradiated males, in contrast to 100 Gy. Thus, 80 Gy was identified as the most promising dose. For further investigation, tests were conducted under choice and no-choice conditions at 80 Gy for three days. The results showed that irradiated males had a comprehensive higher mating rate than non-irradiated males, and under choice conditions, they were often preferred by females, confirming that SIT has potential as an environment-friendly method for controlling B. hilaris.