INSECTICIDAL ACTIVITY OF Bacillus thuringiensis, ACTINOMYCETES AND Serratia marcescens ON Plutella xylostella L. AND Spodoptera litura F.
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Date
2015-06
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Abstract
Investigations were carried out to explore the insecticidal activity in Bacillus
thuringiensis, actinomycetes and Serratia marcescens bacteria against the Plutella xylostella
and Spodoptera litura. Out of the 50 B. thuringiensis isolates tested DBT-388 and DBT-772
recorded 92.00 and 86.00 per cent mortality against P. xylostella, respectively in laboratory.
AIM-213(A) registered 38.00 per cent per cent mortality of S. litura larvae. Twelve promising
isolates which registered more than 75.00 per cent mortality were screened to know the
spectrum of cry genes present in them. Cry1 gene was amplified in eleven, cry2 in eight,
whereas cry8 and cry9 in three and six isolates, respectively. Cry20 was not amplified in any
of the isolates. Among 95 isolates of actinomycetes, AUDT-240 and AUDT-258 reduced the
larval load of P. xylostella by 92.00 and 86.00 per cent respectively in in vitro conditions.
Highest mortality of 80.00 per cent was recorded by AUDT-280 against S. litura larvae.
Insecticidal compounds reported through the GC-MS studies in AUDT-240 isolate are methyl
formate, transp- mentha-2,8-dien-1-ol and 3,9-epoxy-p-mentha-1,8 (10) diene, whereas
compounds from AUDT-258 were methyl formate and 3-furanmethanol. In case of S.
marcescens, no significant mortality was observed in P. xylostella. In case S. litura mortality
was not registered. In AUDS-33, AUDS-111, AUDS-96, AUDS-141 and AUDS-170 isolates of
S. marcescens, ChiA and chiC genes were present. chiB gene was present in four isolates,
except AUDS-111. Water based flowable formulation from promising isolates, two each of Bt
DBT-388, DBT-772; and actinomycetes viz., AUDT-240 and AUDT-258 along with HD-1 were
evaluated in green house. In first season DBT-388 caused highest mortality of 94.00 per cent
followed by AUDT-240 (91%), DBT-772 (88%), HD-1 (85%) and AUDT-258 (84%). In second
season caused highest mortality of was given by DBT-388 (95%) followed by AUDT-240
(90%), DBT-772 (86%), HD-1 (85%) and AUDT-258 (82%).
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