Irradiation as a quarantine treatment for Mexican mangoes

Laboratory experiments involved the irradiation of mangoes infested with third instar larvae of Anastrepha serpentina, A. ludens and Ceratitis capitata, over a range of doses between 10 and 250 Gy. Irradiation was carried out using a Co-60 AECL irradiator model JS-7400. The experiments were designed to achieve a dose distribution equal to or less than 1.025. Fricke dosimeters were used. Fertility tests were carried out on emerged adults of A. ludens and C. capitata; a larval dose of 40 Gy or more resulted in zero fertility in the case of A. ludens, while the corresponding figure for C. capitata was 60 Gy. The adults that emerged of A. serpentina died before reaching sexual maturity. It was concluded that i) irradiation at the dose of 60 Gy totally inhibits the emergence of A. serpentina and A. ludens adults; and ii) the dose of 150 Gy inhibits the emergence of Ceratitis capitata adults from 99.9% of irradiated larvae, and those which survive are sterile. The doses of 60 and 150 Gy exceed the mortality probit 9 threshold, and are within the tolerance limit of fresh fruit (approximately 1000 Gy). (author). 4 refs, 2 figs, 6 tabs