Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2000
Publication Date: 8/20/2001
Citation: Yokoyama, V.Y., Miller, G.T., Crisosto, C.H. 2001. Basic and large-scale tests to determine pest response in packed table grapes to low temperature storage combined with slow release sulfur dioxidepads. Journal of Economic Entomology. Volume(94):984-988. Interpretive Summary: Foreign markets may be available for table grapes produced in the San Joaquin Valley of California, if the fruit complies with quarantine regulations that prevent accidental introductions of California grape pests into areas where the pests are not found. Certain species of thrips, mites, mealy bugs, and caterpillars are pests of concern to countries such as Australia. Methyl Bromide (MB) fumigation is the current acceptable quarantine treatment to control such pests. MB uses may be limited in the future so new treatments are needed.Low temperature combined with slow release sulfur dioxide pads is a method to store grapes for long periods of time. This procedure was investigated as a potential quarantine treatment to control grape pests in basic laboratory tests and large scale commercial tests. Complete control of western flower thrips and grape mealybug and 98- 99% control of twospotted and Pacific spider mites was attained after a six xweek exposure to the treatment in basic tests. In large scale tests an 8 week exposure to low temperature combined with slow release sulfur dioxide pads was effective as a quarantine treatment for western flower thrips, twospotted spider mite, and omnivorous leafroller and attained 92-99% control of grape mealybug and Pacific spider mite. The results of this study show that the combination treatment offers an economical method to achieve quarantine control of certain insects and mites. The procedure can be readily incorporated into existing table grape handling, storage, and shipping procedures. Recently, a U.S. trade partner in South America has shown interest in the proposed quarantine treatment for exports of table grapes to the U.S. during winter months.
Technical Abstract: The effect of low temperature storage combined with slow release sulfur dioxide pads was determined in basic and large-scale tests on western flower thrips, Frankliniella occidentalis, Pergrande; grape mealybug, Pseudococcus maritimus (Ehrhorn); Pacific spider mite, Tetranychus pacificus McGregor; twospotted spider mite, Tetranychus urticae Koch; and, omnivorous leafroller, Platynota stultana Walshingham. Complete control o western flower thrips and grape mealybug was attained after 6 wk. Western flower thrips was completely controlled by a greater or equal to one week exposure. Grape mealybug mortality was greater or equal to 94% after 2-5 wk exposures. However,<2% of Pacific spider mite and <1% of twospotted spider mite survived after a 6 wk exposure. In general, mortality of the spider mites was directly related to the duration of exposure. Large-scale tests showed that an 8 wk exposure to low temperature storage combined with slow release sulfur dioxide pads was as effective as a quarantine treatment for western flower thrips, twospotted spider mite, and omnivorous leafroller. The treatment resulted in <8% survival of grape mealybug and <1% survival of Pacific spider mite. Temperatures within the foam containers among the packed clusters decreased from ambient to 2C within approximately 1 d in all tests and fluctuated thereafter, from approximately 1-3C.Sulfur dioxide concentrations in the foam containers ranged between 0.2-1.6 ppm during the 1-6 wk storage period in basic tests and 0.5-1.1 ppm during the 1-8 wk storage period in large-scale tests. The combination treatment offers an economical method to attain quarantine control of certain insects and mites.