Using the irradiation technique to predict the sperm competition mechanism in Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae): Insights for a future management strategy

Authors: MAINARDI, CHIARA ELIVRA - Bbca-Onlus, Italy; PECCERILLO, CHIARA - Bbca-Onlus, Italy; PAOLINI, ALESSANDRA - Bbca-Onlus, Italy; CEMMI, ALESSIA - Enea Casaccia Research Center; SFORZA, RENÉ - European Biological Control Laboratory (EBCL); MUSMECI, SERGIO - Enea Casaccia Research Center; CRISTOFARO, MASSIMO - Bbca-Onlus, Italy

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2023
Publication Date: 8/1/2023
Citation: Mainardi, C., Peccerillo, C., Paolini, A., Cemmi, A., Sforza, R.F., Musmeci, S., Cristofaro, M. 2023. Using the irradiation technique to predict the sperm competition mechanism in Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae): Insights for a future management strategy. Insects. 14,681. https://doi.org/10.3390/insects14080681.
DOI: https://doi.org/10.3390/insects14080681

Interpretive Summary: One of the greatest challenges of the current century is to avoid control of invasive insect populations through synthetic insecticides: these are extremely expensive and have a major impact on ecosystems. The Sterile Insect Technique (SIT) can help control the target population through a release of adults in the field rendered sterile by irradiation. To evaluate the applicability of this technique, a great deal of knowledge about the biology of the target species is required. In this study, we investigated the mechanism of sperm competition in a polyandrous stink bug species, Bagrada hilaris, the painted bug: in fact, in view of the possible application of SIT, it is important that irradiated males have the same potential to compete with wild non-irradiated ones, even at the post-copulation stage. The results here showed a mechanism of partial sperm mixing.

Technical Abstract: The stink bug Bagrada hilaris is a pest of mainly Brassicaceae crop species. It is native to Africa and Asia and was recently reported as invasive in the southwestern part of the USA, South America. There are no eradication programs in use that do not involve pesticides. Therefore, much attention has recently been paid to the study of this species in order to identify sustainable and effective control strategies, such as the Sterile Insect Technique (SIT). To evaluate the suitability of SIT on this pest, the mechanism of post-copulatory sperm competition was investigated. This is a polyandrous species, and it is important to understand whether irradiated males are able to com-pete with wild, e.g. non-irradiated, males for sperm selection. To determine the paternity of the progeny of multiple mated females, double-cross experiments were set up by confining individual females with either a non-irradiated male or a '-irradiated male (Co-60) at three different doses (60, 80 and 100 Gy). An initial assessment of the sperm competition success with a P2 index was performed. From our data, sperm from the non-irradiated male was preferred at the lowest irradi-ation doses (60 and 80 Gy), in contrast to the highest dose (100 Gy) where the irradiated male suc-ceeded. As a result, Bagrada hilaris exhibited a high variability in P2 indexes, indicating a partial sperm mixing behavior.