Evaluation of the Sterile Insect Technique for the Control of the Melon Fly (Bactrocera cucurbitae) Under Laboratory and Semi-Field Conditions in Sri Lanka

Abstract

The melon fly, Bactrocera cucurbitae, threatens many cash crops in Sri Lanka, including gherkin, pumpkins, and melons. This study aimed to determine the best irradiation dose to induce sterility in melon flies, aiming to establish a Sterile Insect Technique (SIT)-based control strategy. Melon fly colonies were maintained in the lab, and male pupae were exposed to different gamma radiation levels (0 to 110 Gy). The effect of radiation on pupal survival, flight ability, reproduction, and lifespan was investigated using standard methods. The 70 Gy dose resulted in the highest pupal survival and flight ability, along with very low fertility and satisfactory lifespan. Furthermore, the competitiveness of the irradiated males (at 70 Gy) against wild males also remained satisfactory under both laboratory and semi-field settings. Therefore, irradiation of B. cucurbitae pupae at 70 Gy radiation could be recommended as the best dose to establish SIT programmes in Sri Lanka.