MANIPULATING AND ENHANCING CITRUS-FRUIT RESISTANCE TO THE CARIBBEAN FRUIT-FLY (DIPTERA, TEPHRITIDAE)

The natural resistance of citrus fruit to attack by the Caribbean frui t fly (caribfly) varies according to fruit senescence and cultivar. Le mons are virtually immune, oranges are highly resistant, and grapefrui t are initially somewhat resistant, at least before becoming senescent . A method allowing an extension of the innate early-season resistance of grapefruit to fruit flies is described. Elucidation of lemon immun ity factors is needed so that the responsible factors can be incorpora ted into less resistant cultivars, perhaps through use of genetic engi neering techniques. By extending and/or increasing resistance of grape fruit, it may be possible to achieve adequate prevention of caribfly i nfestation throughout most of the season without the need to use expen sive and troublesome postharvest disinfestation treatments in order to ship the fruit to quarantine-sensitive states and countries.