Phytosanitary cold treatment for oranges infested with Bactrocera zonata (Diptera: Tephritidae).

The peach fruit fly, Bactrocera zonata (Saunders), attacks a wide range of tree fruits in countries from Egypt to Vietnam and is occasionally trapped in the United States. Phytosanitary treatments may be required to export fruit hosts of this insect from countries where it is endemic to countries where it is absent but could become established. This research describes comparative studies to determine if B. zonata could be phytosanitarily controlled by cold treatment schedules existing for Ceratitis capitata (Wiedemann) and Anastrepha ludens (Loew), and the development of a cold treatment of 18 d at 1.7 degrees C for B. zonata infesting oranges. Fruit were infested by puncturing holes in oranges and allowing tephritids to oviposit in the holes. The treatments were initiated when the larvae reached late third instar because previous research had shown that stage to be the most cold-tolerant. B. zonata was not found to be confidently as or less cold tolerant than C. capitata; therefore, treatment schedules for the latter are not supported by this research for the former. B. zonata was found to be more susceptible to 1.7 degrees C than A. ludens; therefore, the use of treatment schedules for A. ludens is supported by this research for B. zonata. However, the treatment for A. ludens requires 22 d. A shorter treatment was verified for B. zonata when 36,820 third instars reared from the eggs in oranges were stored at 1.7 degrees C for 18 d with no larvae moving on examination 24 h after removal from the cold treatment chamber.