Bioefficacy of Mycopathogens Verticillium lecanii Zimmermen and Metarhizium anisopliae Metchnikoff against Sucking Pests of Bt Cotton

Entomopathogenic fungi Verticillium lecanii Zimmermen and Metarhizium anisopliae Metchnikoff have generated a great deal of interest in recent years because of their potential as bio-control component in integrated pest management of cotton. These two mycopathogens were evaluated against sucking pests of Bt cotton during Kharif 2011 and 2012 at Cotton Improvement Project, Mahatma Phule Krishi Vidyapeeth, Rahuri to find out the scope and potentiality of V. lecanii and M.anisopliae against sucking pests of Bt cotton in intra hirsutum Bt hybrid (RCH-2Bt). Mycopathogens V.lecanii (2 ×10⁸ cfu/gm and 2 ×10¹² cfu/g) and M.anisopliae @ 2000 g/hectare were evaluated alone and in combination (V. lecanii + M.anisopliae). The observations were recorded on 3,5 and 10 days interval after each spray application. Pooled analysis of two years data revealed that V. lecanii (2 ×10¹² cfu/g) @ 2000 g/hectare + M. anisopliae (2 ×10¹² cfu/g) @ 2000 g/ha in combination was found more effective and significantly superior to its lower dose V. lecanii (2 ×10⁸ cfu/g)@ 2000 g/ha + M. anisopliae (2 ×10⁸ cfu/g) @ 2000 g/ha. It was proved superior over all other treatments in reducing aphids, jassids, thrips and whitefly population, however, it was at par with V. lecanii (2 ×10¹² cfu/g) @ 2000 g/ha. Thus, V. lecanii (2 ×10¹² cfu/g) @ 2000 g/ha was found to be the effective dose against all major sucking pests of cotton. Investigation on evaluation of entomopathogenic fungi against natural enemies of sucking pests in Bt cotton revealed that there was no significant adverse impact of V. lecanii and M. anisopliae on the activity of natural enemies viz., Chrysoperla and Coccinellids; when compared with the population of natural enemies in control. Sole and combine application of V. lecanii and M. anisopliae at all the evaluated doses were not found toxic to natural enemies.