Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 19, 1997
Publication Date: N/A
Interpretive Summary: Commonly used citrus coatings, Citrus Lustr 402 and Sta-Fresh 590HS, were found to provide high levels of kill of Mexican fruit fly eggs and larvae inside of Texas grapefruits. Less mortality was suffered by large larvae which were close to completing feeding. If the grapefruits were not completely coated, the level of control was reduced dramatically. Coating mixed in with the fruit fly's rearing diet did not kill the larvae, demonstrating that the coating was not directly toxic. The mode of action of the coating was probably related to reduced oxygen levels and increased carbon dioxide levels inside of the grapefruits. The use of coatings would fit well into an integrated system of fruit fly abatement where each pest-reducing step in the process decreases the risk of fruit fly infestation to an insignificant level.
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 coatings could be incorporated as a component of an integrated systems approach to quarantine esecurity where a series of pest infestation-reducing steps decrease risk t insignificant levels.