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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGICAL, BEHAVIORAL, AND PHYSICAL CONTROL AS ALTERNATIVES FOR STORED PRODUCT AND QUARANTINE PESTS OF FRESH/DRIED FRUITS AND NUTS Title: Radio frequency energy for postharvest control of pests in dry nuts and legumes

Authors
item Wang, S -
item Tang, J -
item Cavalieri, R -
item Mitcham, E -
item Johnson, Judy

Submitted to: Resource Engineering and Technology for a Sustainable World
Publication Type: Trade Journal
Publication Acceptance Date: February 16, 2009
Publication Date: April 21, 2009
Citation: Wang, S., Tang, J., Cavalieri, R., Mitcham, E., Johnson, J.A. 2009. Radio frequency energy for postharvest control of pests in dry nuts and legumes. Resource Engineering and Technology for a Sustainable World. 16(3):17-19.

Interpretive Summary: With increasing globalization, the international trade of agricultural commodities has become an integral part of the global economy. Agricultural commodities are, however, natural carriers of exotic insect pests. To reduce the risk of introducing pests, importing countries or regions impose quarantine or phytosanitary requirements for the hosts of targeted pests. The fumigant methyl bromide is most often used to disinfest exported products, but it is a highly toxic gas and listed as an ozone depleting chemical under the Montreal Protocol. Critical-use-exemption must be obtained each year from the Parties to the Montreal Protocol for continued use of methyl bromide until commercially viable alternatives are developed. As such, there is an urgent need to find environment-friendly and effective alternatives. Radio frequency (RF) heating, which is a process similar to microwave heating, has been shown to control insect pests in walnuts. RF treatments were developed using the most heat tolerant of the major postharvest in-shell walnut pests, which was found to be navel orangeworm. In a commercial setting, walnuts artificially infested with navel orangeworm were rapidly heated above 52°C in a confined 27MHz RF field. Test insects were completely killed, yet walnut quality was not affected. RF treatment is a physical process and, thus, holds potential as an environment-friendly alternative to methyl bromide for control of insects in walnuts and other low-moisture agricultural commodities.

Technical Abstract: Methyl bromide (MeBr) is widely used as a fumigant in insect control, but it is harmful to the environment and a concern to human health. The Montreal Protocol on Substances that Deplete the Ozone Layer calls for the elimination of MeBr by 2005 in developed countries and by 2015 in developing countries. Critical-use-exemption must be obtained each year from the Parties to the Montreal Protocol for continued MeBr use in postharvest control of insects in agricultural commodities until commercially viable alternatives are developed. Radio frequency (RF) energy was shown to control insect pests in walnuts and is being applied to other products such as legumes. RF treatments were developed based on the thermal death kinetics of navel orangeworm, Amyelois transitella [Walker], the most heat tolerant of the major postharvest in-shell walnut pests. In a commercial setting, walnuts artificially infested with navel orangeworm were rapidly heated above 52°C through rapid rotation of polar water molecules and migration of charged ions in a confined 27MHz RF field. Test insects were completely killed, yet walnut quality was not affected. RF treatment is a physical process and, thus, holds potential as an environment-friendly alternative to MeBr for control of insects in walnuts and other low-moisture agricultural commodities.

Last Modified: 12/21/2014
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