A Probit Analysis of the Disinfestation of Mangosteens by Cold Treatment Againts the Larval Stages of the Oriental Fruit Fly (Bactrocera dorsalis (Hendel)) ( Diptera : Tephritidae)

Abstract

The presence of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera : Tephritidae), in Thailand restricts entry of mangosteens to some foreign markets because of plant quarantine regulations. Mangosteens infested with third instar larvae of B. dorsalis were held at 5, 6 and 7^oC for ¼, ½, 1, 2, 4, 8, 11, 14, 16 and 20 days. Probit regression lines were fitted to the data of the relationship between exposure time and mortality of the insect. The exposure times required to kill B. dorsalis in mangosteens at 99.9968% mortality (probit 9), based on the recovery of puparia or adults, were calculated to be 19.4, 24.9 and 24.9 days for fruit treated at 5, 6 and 7^oC, respectively. Attempts to find alternative procedures given the criterion of probit 9 were discussed.