STUDIES ON NATIVE INSECT PATHOGENS FOR BIOLOGICAL CONTROL OF DBM (Plutetta xylostella Linnaeus) AND HEAD BORER [Helicoverpa armigera Hubner) ON CABBAGE {Brassica oteracea var. Capitata),
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Date
2004
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AAU, Anand
Abstract
Studies on bioefficacy of three native insect patliogens viz. Bacillus thuringiensis (Berliner) (GAU T0B1), Heterortiabditis sp. (GAU A02) and Metarhizium anisopliae var. anisopliae (Metschnikoff) Sorokin (GAU Ma) against Plutella xylostella (Linn.) and Helicoverpa armigera (Hub.) Infesting cabbage were carried out in laboratory, micro plot and field conditions at Gujarat Agricultural University, Anand Campus, Anand during 2002-2003. Laboratory bioassay revealed that native Bt isolate (GAU T0B1) induced maximum mortality (77.50 and 82.50 %) at higher concentration, 10^ sporecrystal mixture/m2 P. xylostella and H. armigera after 168 hrs of treatment respectively. Heterorhabditis sp. (GAU A02) and M. anisopliae (GAU Ma) were also found effective, which incurred more than 50 per cent larval mortality from 168 hrs of treatment at highest dose tested. The bioefficacy of these pathogens against P. xylostella and H. annigera in micro plot under net house conditions, indicated better larval mortality in Bt (65.0 and 67.50%) followed by EPN (42.50 and 42.0%) and M. anisopliae (30.0 and 35.0%). All the treatments remained significantly superior over control. Field experiment showed that among the three pathogens, Bt treatment showed lowest populations 0.75 and 0.10 larva/head of P. xylostella and H. armigera, respectively on 7th day of application followed by EPN and M. anisopliae treatments. Endosulfan reduced quickly maximum pests population of both the insects. The head damage in insect pathogen treatments was observed to be constant, while in control it was further aggravated. Highest yield among the native isolates was recorded in order as Bt (1475.3 kg/ha) followed by Heteroffiabditis sp. (1310.44 kg/ha) and M. anisopliae (1110.65 kg/ha). All the three native pathogens were able to check the populatbn of P. xylostella and H. anvigera effectively and thereby reduced the head damage in cabbage ultimately giving economic yield over control. Considering the yield economics and mortality inflicted, Bt @ 109 spore crystals/m2 was the best among the pathogen evaluated for management of DBM and head borer on cabbage.
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Agricultural Entomology, A Study