‘Sharwil’ Avocado: Quarantine Security Against Fruit Fly (Diptera: Tephritidae) Infestation in Hawaii

Abstract

Laboratory studies with ‘Sharwil’ avocados at 3, 12, or 24 h after harvest showed that the cultivar was not susceptible to infestation by Mediterranean fruit fly, Ceratitis capitata (Wiedemann); melon fly, Dacus cucurbttae Coquillett; or oriental fruit fly, D. dorsalis Hendel for up to 12 h after harvest if the fruits were harvested with stems attached. Similar studies also showed that ‘Sharwil’ avocados were not a host for D. latifrons (Hendel). Packinghouse inspections during the 1984-1985 and 1986-1987 harvest seasons indicated no fruit fly infestations in 114,112 individually inspected ‘Sharwil’ avocados, including 3,438 avocados culed for detached sterns or damage to the fruit surface. Based on these data, USDA allowed the export of ‘Sharwil’ avocados to Alaska during the 1987-1990 harvest seasons. No fruit fly infestation was reported from 53,979 kg of ‘Sharwil’ avocados exported to Alaska. No larval infestations were found in 1,232 ‘Sharwil’ avocados sampled during 1987-1988 from an orchard where oriental fruit flies were observed ovipositing into the fruit. During the 1988-1989 harvest season at the same orchard, 2,439 ‘Sharwil’ avocados were culled for fruit fly ovipunctures (oviposition wounds), disease, surface blemishes and damage, and miscellaneous defects. Less than 4.1% of 1,206 oviposition sites contained dead eggs. No live eggs or larval infestations were found in 426, 539, or 401 fruits culled for ovipunctures, disease, or for miscellaneous defects, respectively. One infested avocado was found in 1,073 fruits culled for surface damage. These studies confirmed that the ‘Sharwil’ avocado is not a host for Mediterranean fruit fly, melon fly, or oriental fruit fly infestations when the fruit is attached to the tree, or when fruits are harvested with stem attached and brought to a fly free packinghouse within 12 h after harvest, culled to remove damaged fruits, and packed in fly-proof boxes. When these regulatory procedures are used to ensure quarantine security, ‘Sharwil’ avocados can be exported from Hawaii without danger of spreading fruit flies.