Research on Quarantine Disinfestation of Mangos

Mangos cannot be transported from Hawaii to markets on the U.S. mainland or in other countries that prohibit the entry of fruit fly hosts without quarantine treatment. Mangos in Hawaii presently have no available quarantine treatments to disinfest the fruit of tephritid fruit flies, including Mediterranean fruit fly, Ceratitis capitata (Wiedemann); melon fly, Bactrocera cucurbitae Coquillett; and oriental fruit fly, B. dorsalis Hendel; or the mango (seed) weevil, Cryptorhynchus mangiferae (F). Whether mangos can be a host for the so-called Malaysian fruit fly, B. latifrons (Hendel), is questionable. Japan imports mangos from Australia, Philippines, Taiwan, and Thailand after the fruits receive a vapor heat disinfestation treatment that raises the fruit pulp temperature to a specified temperature and holds that temperature for 10 20 minutes before hydrocooling. The ARS Hilo laboratory recently completed construction of a vapor heat research facility that will be used to provide data to determine the required parameters for an efficacious quarantine treatment using this technology. Meanwhile, we have been developing a high-temperature forcedair treatment that, to date, shows promise in disinfesting Mediterranean and oriental fruit flies from mangos. The treatment consists of heating mangos with forced hot air at 85 95 percent relative humidity. The fruit surfac(;s remain dry during treatment because the dewpoint of the air is maintained below the fruit surface temperature to preclude condensation onto the fruit. The mango pulp is heated to 47.2°C, measured at the outer seed surface during treatment, followed by hydrocooling until the pulp is 30°C. The data required to demonstrate a probit 9 quarantine security to USDA APHIS is a treated population of 100,000 target insects of the most heat-tolerant life stages with no more than three survivors. Mediterranean and oriental fruit flies are the most heat-tolerant species, and the lateaged eggs and first instar larvae are the most heattolerant life stages. Our accumulated data for the forced hot-air treatment are: 370,805 Mediterranean fruit fly eggs treated, with four survivors. 25,318 Mediterranean fruit fly first instar larvae treated, with zero survivors (74,682 more needed to complete data). 443,789 orie?tal fruit fly eggs treated, with zero survIvors. 114,676 oriental fruit fly first instar larvae treated, with zero survivors. About 30,000 of the less heat-tolerant life stages are needed to show that the forced hot-air treatment provides quarantine security. We hope to complete these data for the forced hot-air treatment this year during mango harvest season. Vapor-heat treatment is identical to a forced hot-air treatment except that water condenses on the fruit surfaces during all or some part of the treatment process. When the forced hot-air treatment data is complete, we will test a vaporheat treatment to show corresponding pulp temperature profiles and insect mortality using Mediterranean and oriental fruit fly eggs and larvae. One to two years will be required to complete this work to provide a second quarantine treatment. Mango weevil remains a major problem. No available treatment technology, other than irradiation, has shown promise as a quarantine treatment, and the temperatures and times required to kill mango weevil with heat also damage the fruit. Microwave treatment, ultrasound detection, and field sanitation were found ineffective. So long as there is no available quarantine treatment against mango weevil, USDA APHIS may not allow the entry of mangos from Hawaii into the U.S. mainland regardless of applicable fruit fly disinfestation treatments. Japan imports mangos from countries where mango weevil occurs and, although there is a zero tolerance for mango weevil, evidently does not inspect for this insect at this time. With applicable quarantine treatments against fruit flies, some countries may accept mangos from Hawaii without disinfestation treatment against mango weevil. The inherent danger is that quarantine regulations may change.