DETERMINING AN OPERATIONAL X-RAY DOSE FOR STERILIZING AEDES AEGYPTI ADULT MALES TOWARD STERILE INSECT TECHNIQUE DEPLOYMENT IN ST. JOHNS COUNTY, FLORIDA

Abstract

Control of Aedes aegypti populations remains a major challenge due to multiple factors, including widespread development of insecticide resistance, daytime biting preference, and cryptic breeding and resting sites. Sterile Insect Technique (SIT) has emerged as a promising complementary tool within integrated vector management programs, demonstrating promising results. The mosquito control program in St. Johns County, Florida, has been developing an in-house SIT program following the phased conditional approach recommended by the World Health Organization and International Atomic Energy Agency. This study aimed to determine the minimum X-ray dose required to induce ≥99% sterility in adult male Ae. aegypti of the local strain while maintaining high sterile male quality. A dose-response experiment was conducted, followed by assessments of survival, longevity and mating competitiveness. An absorbed X-ray dose of 47.13 ± 2.09 Gy (± SD) achieved 99% sterility without significantly affecting the survival and longevity of adult males. Fried’s competitiveness index estimated for males irradiated at a target dose of 50 Gy (mean ± SD: 1.12 ± 0.12) indicated that the irradiated males were as competitive as unirradiated males. A 5:1 irradiated: unirradiated ratio achieved an 84% induced sterility, which was not significantly different at the 10:1 ratio. No significant differences in competitiveness were observed among 1:1, 5:1 and 10:1 ratios. Based on these results, a 50 Gy dose of X-rays was selected as the operational dose for adult males of the local Ae. aegypti strain.