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Department of Entomology, S.V. Agricultural College, ANGRAU, Tirupati-517 502.
Diamondback moth larvae were reared on natural diet (cabbage) with three concentrations of Streptomycin sulphate (0.05, 0.1 and 0.2%) and without antibiotic (control). Mean larval developmental period was prolonged to 10.00, 11.00 and 12.00 days at 0.05, 0.1 and 0.2 per cent antibiotic respectively, compared to untreated natural diet (9.00 days). Among the concentrations of antibiotic tested, a dose of 0.2 per cent resulted in reduced pupal recovery (67.40%) with shortest pupal duration (4.23 days). Emergence of adults was drastically decreased from 85.80 per cent (control) with a higher number of females (1.5 f/m) to 57.80 per cent (0.2per cent antibiotic) with higher number of males (0.8 f/m). Females laid a greater number of eggs on untreated diet (151.70 eggs/female), with highest percent egg hatchability (82.16%), while a marked reduction was observed at 0.2 per cent antibiotic with 95.38 eggs/female and 58.25 per cent egg hatchability. Biological parameters of Plutella xylostella were negatively affected at all the three concentrations of Streptomycin sulphate and it was more obvious at 0.2 per cent antibiotic dose.
KEYWORDS: Diamondback moth, Streptomycin sulphate, Natural diet, biological parameter.