Mortality of Mexican Fruit Fly (Diptera: Tephritidae) Immatures in Coated Grapefruits

Coatings applied to fruits have been shown to kill tephritid fruit fly immatures inside of the fruits. The present research investigated the efficacy of coatings against distinct life stages of Mexican fruit fly, Anastrepha ludens (Loew), and results showed high levels of disinfestation of grapefruits of up to the early third instar (95%) for one commonly used grapefruit coating, Citrus Lustr 402. Emergence was reduced significantly even for late third instars. Leaving one-third of each grapefruit uncoated reduced efficacy considerably. Mixing Citrus Lustr 402 into the diet used to rear Mexican fruit fly did not affect survival indicating that this coating is not toxic to larvae. This research supports the hypothesis that coatings act primarily to modify atmospheres inside the fruits and kill larvae by restricting gaseous exchange. Fruit coating could be incorporated as a component of an integrated systems approach to quarantine security where a series of pest infestation-reducing steps decreases risk to insignificant levels.