Optimal Low-pressure Conditions for Long-term Storage of Fresh Commodities Kill Caribbean Fruit Fly Eggs and Larvae

Abstract

U.S. regulations prevent importation of fresh horticultural commodities that have not received an approved quarantine treatment assuring 99.999% (Probit 9) mortality of potentially invasive insect pests. Because imported mangoes (Mangifera indica) are likely to be infested by the caribbean fruit fly (Anastrepha suspensa) and other tropical fruit flies in the Americas, such as the mexican fruit fly (A. ludens), guava fruit fly (A. striata), inga fruit fly (A. distincta), south american fruit fly (A. fraterculus), sapote fruit fly (A. serpentina), and the west indian fruit fly (A. obliqua), they must be hot-water treated prior to shipment in order to satisfy quarantine requirement. Hot water treatment often damages the fruit, especially if it is not fully mature. Hypobaric [low pressure (LP)] intermodal shipping containers developed by the VacuFresh Corp. preserve fresh commodities, such as horticulturally mature mangoes, far longer than is possible using other technologies. We tested the ability of caribbean fruit fly eggs and larvae to survive simulated optimal hypobaric conditions for shipment of mangoes [15 and 20 mm mercury (Hg), ≥98% relative humidity, 13 °C (the lowest, safe nonchilling temperature)]. Caribbean fruit fly eggs or larvae were maintained on agar media, flushed with one air change per hour at the storage pressure, and shielded with Mylar to prevent radiant heat uptake and limit evaporative cooling. Nearly 98% of the eggs and larvae were killed within 1 week at 15 and 20 mm Hg in nine replicated experiments. All eggs were killed by 11 days with a predicted kill of 99.999% of the eggs by 9.4 days in 15 mm Hg and 10.6 days in 20 mm Hg LP (based on Probit 9 statistical analysis), whereas a substantial number of eggs survived to 14 days at atmospheric pressure (760 mm Hg). Shipment of fresh produce using this technology promises to provide quarantine control while preserving the freshness of fully mature tropical fruits and vegetables.