Shelf-life of spicturin~(R) (Bacillus thuringiensis Berl. var. gallariae) during storage and its efficacy against Plutella xylostella (L.) on cauliflower

摘要

The shelf-lift: studies were conducted to determine the shelf-life of SPICTURIN~(R) (Bacillus thuringiensis Berl. var. gallariae) against Plutella xylostella L. on cauliflower by two methods viz., from the unopened samples and opened sample of Spicturin. In the first method, 18 fresh samples of Spicturin were stored at room temperature (25 to 33 deg C) and each month one sample was opened for bioassay and enumeration of spore load. The bioassays were conducted for 18 months continuously by leaf-dip method. In the second method, first month opened sample was stored at room temperature and used for similar study. The present results indicated that Spicturin samples were found to maintain the spore load of 10~7 spores ml~(-1) for 18 months and there was not much reduction in viable spores in the first month opened sample. However, there were differences in the initial spore load itself in the first method. From the 18 months storage study on Spicturin, the results of both the methods exhibited that the mortality of the second and third instar larvae of P. xylostella varied from 95.00 to 85.00 and 85 to 75.00 per cent respectively for Spicturin 4ml L~(-1) which was higher when compared to lower doses of 3 and 2ml L~(-1); however, it was on par with them.