Methyl bromide quarantine treatment for codling moth (Lepidoptera: Tortricidae) in unshelled walnuts
1991
Hartsell, P.L. | Vail, P.V. | Tebbets, J.S. | Nelson, H.D.
Unshelled walnuts were artificially infested with diapausing fifth-instar codling moth, Cydia pomonella (L.), and fumigated with 56 g/m3 methyl bromide for 4 h at 15.6 degrees C under a reduced pressure of 100 mm Hg. When 34,959 were treated, 1 larva survived, indicating a-survival rate of 2.91 larvae/100,000 treated. The upper 95% CL for this survival rate was 13.8 larvae/100,000 treated. When larval survival rates of methyl bromide fumigation tests of a normally applied domestic treatment were combined with survival rates from quarantine vacuum fumigation tests, the 95% CL survival rates were less than or equal to 0.4 larva/100,000 treated. No significant differences were found in mortality of larvae among the four walnut cultivars tested, nor was variation in the size of walnuts of each cultivar a significant factor. Because whole walnuts sorbed 79.6% of the methyl bromide applied, a relatively high rate of methyl bromide was required to obtain an efficacious treatment. The treatment was accepted by the Japanese Ministry of Agriculture, Forestry and Fisheries in 1986.
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