ECOFRIENDLY APPROACHES FOR THE MANAGEMENT OF Spodoptera litura (F.) IN GROUNDNUT
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Date
2001-08-06
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK BANGALORE
Abstract
Ecofriendly methods for the effective management of Spodoptera litura in
groundnut were studied during 1996 to 1998 at Main Research Station, UAS,
Dharwad. The EIL computed for third instar larvae of S. iitura at flowering (30 DAS),
peg formation (45 DAS) and pod development (60 DAS) stages was 1.04, 2.18 and
3.59 larvae per plant. At the corresponding stage, the egg load required to cause
economic damage was 1.32, 2.90 and 8.74 egg masses per 7.5 m^ or 25 m row,
respectively. Annona squamosa, NSKE (5%) and AUium sativum (5%) exhibited
good ovicide. property causing around 30 per cent mortality as compared to cent
per cent in rr.ethomyl in vitro. The aqueous extract of NSKE (5%), Vitex negundo
and A. squamosa caused more than 52 per cent mortality in neonate larvae. Among
various comcinations of plant products, NSKE + SINPV, V. negundo + SINPV,
NSKE + Nomuraea rileyi and V. negundo + N. riieyi qtoved equally as recommended
insecticides "n reducing damage and recording higher yield with better B:C ratios.
Vitex negundo and A. mexicana in combination with monocrotophos (0.025%)
and V. negundo followed by monocrotophos (0.05%) recorded equal yield compared
to recommended package.
The entomopathogenic fungus, N. /■/Vey/occurred in epizootic form on S. iitura
in groundnut during the rainy season. Persistence of N. rileyi on groundnut foliage
during kharif v/as upto ten days. In vitro studies on compatibility of entomopathogen
with fungicices, insecticides and botanicals indicated that fungicides were highly
detrimental followed by insecticides and plant products. Soil application of the
pathogen @ 2.5 x 10 12 conidia per ha followed by foliar spray (S 1.2 x 10 11 conidia
per ha follov.ed by spraying monocrotophos (0.05%) mixed with cyperconazole
(0.1%) were :he most effective combined applications.
All the groundnut genotypes under the study exhibited moderate to high degree
or tolerance to the defoliator. Among the different histological
-igher laminar thickness, cuticular thickness and low water content
=d for imparting resistance. Low growth index in Dh-52, Dh-53 and
:ed the antibiosis mechanism operating in imparting resistance to
'ence in yield between unprotected and protected condition in selected
:S less compared to susceptible check (JL-24) indicating the tolerance
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