NEW IRRADIATION DOSES TO CONTROL HAWAII¿S FRUIT FLIES: TOWARDS A GENERIC DOSE FOR TREPHRITIDS.

Authors: Follett, Peter; Armstrong, John

Submitted to: International Symposium on Fruit Flies of Economic Importance
Publication Type: Proceedings
Publication Acceptance Date: 1/15/2004
Publication Date: 11/15/2004
Citation: Follett, P.A., Armstrong, J.W. 2004. New irradiation doses to control hawaii¿s fruit flies: towards a generic dose for trephritids. P237-240. Proc. 6th International Symposium on Fruit Flies of Economic Importance, 6-19 May 2004, Stellenbosh, South Africa.

Interpretive Summary: Irradiation studies were conducted with melon fly, oriental fruit fly, and Mediterranean fruit fly to reduce currently approved doses that are unnecessarily high. Melon fly was the most tolerant of the three species to irradiation, contrary to previous findings. Laboratory and wild strains of melon fly were equally tolerant of irradiation, and flies were more tolerant when irradiated in fruit compared with diet. An irradiation dose of 150 Gy applied to 50,000 melon fly mature third instars in papayas resulted in 0 survivors to the adult stage, indicating that this dose is sufficient to provide quarantine security for melon fly. Results support a proposed generic irradiation quarantine treatment dose of 150 Gy for all tephritid fruit flies.

Technical Abstract: Approved irradiation quarantine treatment doses for melon fly, Bactrocera cucurbitae, Mediterranean fruit fly, Ceratitis capitata, and oriental fruit fly, Bactrocera dorsalis infesting fruits and vegetables for export from Hawaii to the continental U.S. are 210, 225, and 250 Gy, respectively. Irradiation studies were initiated to determine whether these doses are unnecessarily high and could be reduced. Dose response tests were conducted with mature third instars of wild and lab strains of the three fruit fly species, both in diet and in fruit. After irradiation treatment, development of each individual in a test was followed until death while recording adult emergence and adult female fertility. Melon fly was the most tolerant of the three species to irradiation. Laboratory and wild strains of melon fly were equally tolerant of irradiation, and flies were more tolerant when irradiated in fruit compared with diet. An irradiation dose of 150 Gy applied to 50,000 melon fly mature third instars in papayas resulted in 0 survivors to the adult stage, indicating that this dose is sufficient to provide quarantine security. Lowering the irradiation dose for these quarantine insects would reduce costs and increase capacity for treatment facilities. Results support a proposed generic irradiation quarantine treatment dose of 150 Gy for all tephritid fruit flies.