Reliability of CT Products in Varieties of Perishable Commodities Fumigated with Methyl Bromide

摘要

To evaluate the reliability of the CT product as an indicator of insecticidal efficacy of methyl bromide (MB), the laboratory scale test was conducted with different varieties of apples ('Alps Otome' and 'Mutsu') and nectarines ('Fantasia' and 'Shuhou') infested with egg and larval stages of the peach fruit moth, Carposina sasakii. The result showed that (1) the difference of the LC_(50's) was smaller than that of the LDso's in two varieties of apples and nectarines when compared the concentration-mortality data with the dose-mortality data. The data suggested that if gas concentration (CT product) was the same, the same efficacy would be obtained between varieties, while even if the same dose was applied, there would be a possibility of differencein efficacy between varieties, and that (2) no significant difference was observed on eggs' response between varieties of 'Alps Otome' and 'Mutsu' apples and of 'Fantasia' and 'Shuhou' nectarines in both the LC_(50's) and the LD_(50'), respectively. However, 95% confidential limits between apple varieties were slightly overlapped with a slight difference each other in the LDso's. The data indicated that there might be significant difference in efficacy between two apple varieties if larger difference was obtained between confidential limits in the LD_(50's), and that (3) no difference was observed on the mortality of the larval stage inside different sizes of 'Mutsu' (the weight ratio is approx 1:2.3), while the mortality in extremely small size of 'Alps Otome' was always higher than that in extremely large size of 'Mutsu' with the difference of 6.8～8.9% (the weight ratio is approx 1:9.2) and there is a possibility with the difference in efficacy in extremely large size of fruit because of influenceof gas penetration.