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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Commodity Protection and Quality Research » Research » Publications at this Location » Publication #115756
Title: CONTROL OF COWPEA WEEVIL, CALLOSOBRUCHUS MACULATUS, USING FREEZING TEMPERATURES.

Author
item Johnson, Judy
item Valero, Karen

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/20/2000
Publication Date: 11/20/2000
Citation: JOHNSON, J.A., VALERO, K.A. CONTROL OF COWPEA WEEVIL, CALLOSOBRUCHUS MACULATUS, USING FREEZING TEMPERATURES. MEETING ABSTRACT. 2000.

Interpretive Summary: California is responsible for roughly 80% of the black-eyed peas (cowpeas)and more than 40% of garbanzo beans (chickpeas) produced in the United States. A serious postharvest pest of these products is the cowpea weevil, Callosobruchus maculatus (Coleoptera: Bruchidae). Loss of methyl bromide and possible restriction of phosphine, in addition to the rising popularity of organic produce lines, has created interest in non-chemical disinfestation treatments. One alternative is the use of cold storage. Although this method has been recommended since the 1920s, detailed information on the response of cowpea weevil to commercial freezer temperatures is not available. To develop more useful recommendations, the most cold tolerant stage of the insect, the exposure times necessary for control at commercial freezer temperatures (about 18C), and the effect of slow cooling rates on treatment efficacy are being determined. Preliminary results indicate that cowpea weevil may be easily controlled by temperatures found in commercial freezers. With rapid cooling rates, exposures of 6 - 24 hours reduced pest numbers by more than 99%. There is concern, however, that gradual cooling may allow pest insects to acclimate to freezing temperatures, extending the require treatment time for disinfestation. This study found that cooling rates for the center of bean bins can be very slow, requiring 19 days to reach target temperatures. Researchers are currently examining the effect of cooling rate on treatment efficacy in order to develop realistic treatment.

Technical Abstract: California is responsible for roughly 80% of the black-eyed peas (cowpeas)and more than 40% of garbanzo beans (chickpeas) produced in the United States. A serious postharvest pest of these products is the cowpea weevil, Callosobruchus maculatus (Coleoptera: Bruchidae). Loss of methyl bromide and possible restriction of phosphine, in addition to the rising popularity of organic produce lines, has created interest in non-chemical disinfestation treatments. One alternative is the use of cold storage. Although this method has been recommended since the 1920s, detailed information on the response of cowpea weevil to commercial freezer temperatures is not available. To develop more useful recommendations, the most cold tolerant stage of the insect, the exposure times necessary for control at commercial freezer temperatures (about 18C), and the effect of slow cooling rates on treatment efficacy are being determined. Preliminary results indicate that cowpea weevil may be easily controlled by temperatures found in commercial freezers. With rapid cooling rates, exposures of 6 - 24 hours reduced pest numbers by more than 99%. There is concern, however, that gradual cooling may allow pest insects to acclimate to freezing temperatures, extending the require treatment time for disinfestation. This study found that cooling rates for the center of bean bins can be very slow, requiring 19 days to reach target temperatures. Researchers are currently examining the effect of cooling rate on treatment efficacy in order to develop realistic treatment.