Gina T. Miller

Pest Response in Packed Table Grapes to Low Temperature Storage Combined with Slow-Release Sulfur Dioxide Pads in Basic and Large-Scale Tests

Abstract The effect of low temperature storage combined with slow release sulfur dioxide pads was determined in basic laboratory and large-scale commercial tests on western flower thrips, Frankliniella occidentalis Pergande; grape mealybug, Pseudococcus maritimus (Ehrhorn); Pacific spider mite, Tetranychus pacificus McGregor; twospotted spider mite, Tetranychus urticae Koch; and omnivorous leafroller, Platynota stultana Walshingham. Temperatures within the foam containers among the packed clusters decreased from ambient to 2°C within approximately 1 d and ranged from 0.4 to 1.7°C in all tests. Sulfur dioxide concentrations in the foam containers ranged between 0.2 and 1.6 ppm during the 1- to 6-wk storage period in basic tests and 0.5–1.1 ppm during the 1- to 8-wk storage period in the large-scale test. Western flower thrips was completely controlled by a ≥1-wk exposure. Grape mealybug mortality was ≥93% after 2–5 wk exposures and 100% after a 6-wk exposure in basic tests. Pacific spider mite and twospotted spider mite mortality was 98.0 and 99.6%, respectively, after a 6-wk exposure. Mortality of grape mealybug and twospotted spider mite increased significantly at ≥3-wk exposures and Pacific spider mite mortality increased significantly at ≥4-wk exposures. Mortality of the spider mites in general was directly related to the duration of exposure. An 8-wk exposure to low temperature storage combined with slow release sulfur dioxide pads in the large-scale test resulted in 100% mortality of 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 in the large-scale test. The combination treatment offers an economical method to attain quarantine control of certain insects and mites.

Bale Compression and Hydrogen Phosphide Fumigation to Control Cereal Leaf Beetle (Coleoptera: Chrysomelidae) in Exported Rye Straw

Abstract Control of larvae and adults of cereal leaf beetle, Oulema melanopus (L.), by bale compression and hydrogen phosphide fumigation was studied in rye straw, Secale cereale L., in Aurora, OR. Natural mortality of larvae after transport was 4.0 ± 1.0% (mean ± SEM). Compression (105 kg/cm2) of larvae in standard bales (122 cm long) of rye straw resulted in 100% mortality. Compression of adults in standard bales plus storage of the compressed bales (56 cm long) for 1 d in a freight container resulted in 100% mortality. A KD50 of 102 ppm hydrogen phosphide for 1 h was estimated from the probit regression line developed from dose–response data at 21°C in basic laboratory tests. The LD50s and LD99s were 163 and 6,910 ppm for 2-h exposures and were 18 and 42 ppm for 6-h exposures at 21°C, respectively. A tested dose of 400 ppm for 24 h at 21°C resulted in 100% mortality of the adults. Larvae (n = 10,560) and adults (n = 18,602) did not survive exposure to bale compression followed by hydrogen phosphide fumigation (60 g/28.3 m3) for 3 d in rye straw loaded in freight containers in large-scale tests. Copper plate corrosion values indicating the severity of exposure to hydrogen phosphide were 13 and 12, and mean temperatures of five locations in the freight container were 25 and 26°C in large-scale tests with the larvae and adults, respectively. Hydrogen phosphide concentrations were ≥400 ppm throughout the 3-d fumigation for larvae and during the first day of fumigation for adults. We propose that cereal leaf beetle can be controlled by a single treatment of bale compression followed by a 1-d storage period or by a fumigation in which 400 ppm hydrogen phosphide is maintained for 1 d at 21°C or above. We confirmed that a multiple quarantine treatment of bale compression followed by a 3-d fumigation will control cereal leaf beetle in exported rye straw.

Response of Omnivorous Leafroller (Lepidoptera: Tortricidae) and Onion Thrips (Thysanoptera: Thripidae) to Low-Temperature Storage

Abstract Eggs and first–fifth instars of omnivorous leafroller, Platynota stultana Walshingham, had a mean percentage survival to the adult stage of 60.7–95.2% for nonexposed immatures and 14.5–54.3% for immatures exposed to 1 wk at 0–1°C. Exposures of 2–5 wk resulted in 0–6.7% survival, and a 6-wk exposure resulted in <1% survival of all stages tested. A significant reduction in survival of all larval stages occurred between exposures of 0 and 1 wk and between 1 wk and 2–6 wk. Survival of eggs after exposures of 0 and 1 wk was significantly different than survival after exposures of 2–6 wk. The second instar was the stage least susceptible to low-temperature storage. Adults that were exposed to low temperature for 1 wk in the third through fifth instars laid a mean of 120–289 eggs per female, and the mean percentage viability of the eggs ranged from 56.2 to 71.4%. Mean percentage survival of adults and nymphs of onion thrips, Thrips tabaci Lindeman, was inversely related to the duration of exposure from 1 through 3–6 wk at 0–1 and 5°C and was lower at 0–1 (0.2–52.5%) than at 5°C (17.6–66.6%). Exposure to 0–1°C for 4 wk attained 91.2% control, which increased to 99.8% after 6 wk. Low-temperature storage has potential to control omnivorous leafroller in table grapes, Vitis vinifera L., and onion thrips in onions, Allium cepa L.

Large-Scale, On-Site Confirmatory, and Varietal Testing of a Methyl Bromide Quarantine Treatment to Control Codling Moth (Lepidoptera: Tortricidae) in Nectarines Exported to Japan

Abstract In total, 30,491 codling moth, Cydia pomonella (L.), 1-d-old eggs on May Grand nectarines in two large-scale tests, and 17,410 eggs on Royal Giant nectarines in four on-site confirmatory tests were controlled with 100% mortality after fumigation with a methyl bromide quarantine treatment (48 g3 for 2 h at ≥21°C and 50% volume chamber load) on fruit in shipping containers for export to Japan. Ranges (mean ± SEM) were for percentage sorption 34.7 ± 6.2 to 46.5 ± 2.5, and for concentration multiplied by time products 54.3 ± 0.9 to 74.5 ± 0.6 g · h/m3 in all tests. In large-scale tests with May Grand nectarines, inorganic bromide residues 48 h after fumigation ranged from 6.8 ± 0.7 to 6.9 ± 0.5 ppm, which were below the U.S. Environmental Protection Agency tolerance of 20 ppm; and, organic bromide residues were <0.01 ppm after 1 d and <0.001 ppm after 3 d in storage at 0–1°C. After completion of large-scale and on-site confirmatory test requirements, fumigation of 10 nectarine cultivars in shipping containers for export to Japan was approved in 1995. Comparison of LD50s developed for methyl bromide on 1-d-old codling moth eggs on May Grand and Summer Grand nectarines in 1997 versus those developed for nine cultivars in the previous 11 yr showed no significant differences in codling moth response among the cultivars.