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Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/5/2005 Publication Date: 2/1/2006 Citation: Follett, P.A. 2006. Irradiation as a methyl bromide alternative for postharvest control of Omphisa anastomosalis (Lepidoptera: Pyralidae), Euscepes postfasciatus and Cylas formicarius elegantulus (Coleoptera: Curcuionidae) in sweetpotatoes. Journal of Economic Entomology. 99(1): 32-37. Interpretive Summary: Until recently, growers have been exporting sweetpotatoes (Ipomoea batatas [L.] Lam.) from Hawaii to the U.S. mainland using methyl bromide fumigation to control three sweetpotato pests. Methyl bromide was identified as an ozone depleting substance and its use is being phased out. Methyl bromide fumigation adversely affects sweetpotato root quality and has become costly. Irradiation treatment is a viable alternative to chemical fumigation for sweetpotato growers. The main advantage of irradiation as a phytosanitary treatment is that it is broadly effective against arthropod pests at dose levels that do not cause injury to most types of fresh fruits and vegetables, including sweetpotatoes Irradiation studies were conducted with three sweetpotato pests to determine an effective dose for quarantine control. Dose response tests indicated that the most radiotolerant stage occurring in roots was the late pupa of Omphisa anastomosalis (Guenee) and the adult of Euscepes postfasciatus (Fairmaire) and Cylas formicarius elegantulus (Summers). In large-scale confirmatory tests, irradiation of 60,000 Cylas formicarius elegantulus adults, 62,323 Euscepes postfasciatus adults, and 30,000 Omphisa anastomosalis late pupae at a dose of 150 Gy resulted in no production of F1 adults, demonstrating that this dose is sufficient to provide quarantine security. Technical Abstract: Quarantine or phytosanitary treatments eliminate, sterilize or kill regulatory pests in exported commodities to prevent their introduction and establishment into new areas. Irradiation is a versatile technology to disinfest fresh and durable agricultural commodities of quarantine pests. Irradiation is broadly effective against insects and mites, cost competitive with other disinfestation methods (such as fumigation, heat and cold) and fast. Irradiation studies were conducted with three sweetpotato (Ipomoea batatas [L.] Lam.) pests to determine an effective dose for quarantine control. Dose response tests indicated that the most radiotolerant stage occurring in roots was the late pupa of Omphisa anastomosalis (Guenee) and the adult of Euscepes postfasciatus (Fairmaire) and Cylas formicarius elegantulus (Summers). In large-scale confirmatory tests, irradiation of 60,000 Cylas formicarius elegantulus adults, 62,323 Euscepes postfasciatus adults, and 30,000 Omphisa anastomosalis late pupae at a dose of 150 Gy resulted in no production of F1 adults, demonstrating that this dose is sufficient to provide quarantine security. Currently, sweetpotatoes are exported from Hawaii to the U.S. mainland after irradiation treatment at 400 Gy. Our research demonstrates that the treatment dose can be reduced from 400 to 150 Gy, which will lower treatment costs and minimize any adverse effects on quality. |
