Insecticidal activity of native Bacillus species against brinjal shoot and fruit Borer, Leucinodes orbonalis (Lepidoptera: Crambidae)

Abstract

Brinjal (Solanum melongena L.), is an economically important vegetable crop cultivated across the world. Shoot and fruit borer, Leucinodes orbonalis (Guenée) is the major biotic stress in brinjal crop. The insecticidal activities of the twenty six strains of Bacillus comprising of Bacillus thuringiensis (17), B. subtilis (5), B. pumilus (2), B. atrophaeus (1) and B. amyloliquifaciens (1) along with reference strain i.e. B. thuringiensis sub species kurstakiHD1were screened at single concentration of 10 μgg-1of diet against neonates of L. orbonalis using diet incorporation method. On 7th day after treatment, the highest mortality was observed in B. thuringiensis reference strain HD1 (100%) followed by 96% (VKK-13 and VKK-BB2) and 80% (VKK-BB1) mortality with native Bt strains. Moreover, endophytic bacteria B. atrophaeus, VKK-6OL and B. subtilisstrain resulted in 68% and 52% mortality respectively. Median lethal concentration (LC50) the potential Bt strains revealed that Btk HD1 (LC50=0.49μg/g of diet) and BtVKK-BB2 (LC50=0.59μg/g of diet) were found to be at par as their fiducial limits are overlapping. Results suggested that besides B. thuringiensis, B. atrophaeus and B. subtilis strains also have insecticidal activity against BSFB and could be suitable for development of bio formulations in future.