Gamma Radiation and Cold Treatments for the Disinfestation of the Mediterranean Fruit Fly in California-Grown Oranges and Lemons

Low-dose gamma radiation and cold treatments were tested for their effectiveness in the disinfestation of the Mediterranean fruit fly, Ceratitis capitata, from California-grown navel oranges and Calfame lemons. Cold treatments were applied for 7, 14, or 21 days to simulate postharvest storage and/or shipment durations and temperatures (5.5°C for oranges and 11.1°C for lemons). Low-dose gamma radiation treatments were applied at various dosages, both independent of and in tandem with cold treatments. The results of egg hatchability and larval survival studies show that a synergistic effect is observed when gamma radiation and cold treatments are used in tandem. The data show that infested navel oranges stored for 14-21 days at 5.5°C required a radiation dose of 0.30 kGy or less to result in very low, or no, hatch of mature medfly eggs. Furthermore, identical treatment of mature medfly larvae resulted in no adult eclosion from pupae. Shorter durations of cold storage, however, require considerably higher dosages to observe similar mortality rates and may not be desirable as fruit quality may be affected at these higher do sages . Calfame lemons require higher dosages than oranges to ob serve similar mortality rates at the same cold treatment durations due to the higher temperature 11.1°C) at which they are stored. The data show that irradiation at 0.30 kGy with cold storage of 21 days or irradiation at 0.50 kGy with cold storage of 14 days is sufficient to cause nearly total egg mortality

Ecology and Evolution of Drosophila ambochila, A Rare Picture-Winged Species Endemic to the Wai'anae Range of O'ahu, Hawaiian Islands

The rare O'ahu picture-winged fly Drosophila ambochila Hardy & Kaneshiro is endemic to two windward ravines in the Wai'anae Mountains that harbor its host plant. Drosophila ambochila is an ecological specialist that breeds on Pisonia stems and trunks in an intermediate stage of decay. By providing field-collected females with suitable substrate material, we have been able to observe the oviposition behavior of this species in the laboratory and obtain F 1 larvae. In nature, females oviposit each batch of mature eggs ("'4050) in a single cluster, by repeatedly inserting their long ovipositor into the same crack or beetle hole in the decaying Pisonia bark. Ovipositor, ovary, and egg morphology are characteristic of bark-breeding Hawaiian Drosophila, but SEM studies revealed a distinctive chorionic ultrastructure for the eggs of this species. Larval salivary chromosome analyses indicated that the O'ahu D. ambochila is most closely related to D. alsophila from the island of Hawai'i and have helped to resolve the phylogenetic relationships among six of the nine species belonging to the vesciseta subgroup of the glabriapex species group

Gamma Radiation Treatment for Disinfestation of the Mediterranean Fruit Fly in California Grown Fruits. I. Stone Fruits

A study was conducted to investigate the effectiveness of gamma irradiation for disinfesting California grown stone fruits which contain eggs and larvae of the Mediterranean fruit fly, C. capitata. Several varieties of plums, peaches, and nectarines, and one variety each of cherries and apricots were investigated. It was found that the different varieties of fruits as well as fruit quality, i.e., ripeness, water content, bruised areas on the fruit, may have a pronounced effect on the effectiveness of the gamma radiation treatment. However, despite varying degrees of survival due to fruit quality, in all of the egg hatchability and larval survival studies, none of the treated individuals survived to emerge as adults at dosages less than 0.60 kGy. Our studies indicate that the gamma radiation technology might indeed be considered a possible alternative to quarantine treatment with chemical fumigants such as ethylene dibromide (EDB)

Ethological Isolation Among Three Species of the planitibia Subgroup of Hawaiian Drosophila.

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