Studies on the insecticidal properties of datura metel against helicoverpa armigera (Hubner)
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Date
2005
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Publisher
CCSHAU
Abstract
The studies on the insecticidal properties of Datura metel leaves
and seeds extract in methanol and its fractions in hexane, benzene,
chloroform and acetone were conducted under laboratory conditions against
Helicoverpa armigera (Hubner). Treatments included 2.5, 5.0, 7.5, 10.0 per
cent concentrations of methanol extract and 0.5, 1.0, 1.5, 2.0 per cent
concentrations of fractions to compare the results with water/acetone as
control. Methanol extracts (2.5,5.0,7.5,10.0%) of leaves and seeds of Datura
metel and their fractions (0.5,1.0,1.5,2.0%) in benzene, acetone, chloroform
and hexane were evaluated against Helicoverpa armigera (Hubner). Leaf
extracts and fractions treated food showed significant effect on larval
mortality (12.22-74.43%), larval period (12.00-18.33 days), larval weight
(303-495 mg), pupation (30.38-87.31%), pupal period (9-11.33 days) and
adult emergence (28.33-86.95%). Almost similar results were obtained with
the extracts and fractions of seeds. In contact toxicity experiment, first instar
larval mortality ranged from 26.66% (2.5% methanol extract) to 76.66% (2.0%
benzene fraction) in leaf extract and fractions. Corresponding mortality in
seeds extracts and fractions was 30.0 to 80.0%. Leaf extract and fractions
also caused significant effect on CI (3.41-8.58), GR (0.14-0.35mg/day), ECI
(2.57-7.52%), AD/AE (87.65-98.06%) and ECD (2.62-9.81%). Similar results
were obtained with Datura seeds. Antifeedancy due to extract and fractions of
leaves ranged from 5.08% in 0.5% benzene fraction to 39.46% in 2% acetone
fraction. In Datura seeds it ranged from 7.01% in 0.5% hexane fraction to
41.15% in 2% acetone fraction. Under oviposition studies, adults were
allowed to lay eggs on oviposition substrate under choice, no choice and
without actual contact situations. Minimum eggs were laid in 10% methanol
extract treatment while maximum were laid in benzene fraction 0.5%. Effects
of leaves and seeds were almost similar. When the adults were allowed to feed
on sucrose diet containing different concentrations of extract and fractions of
Datura leaves, number of eggs laid ranged from 151(2% chloroform fraction)
to 241 (0.5% hexane fraction) and hatching ranged from 64.88% (2% hexane
fraction) to 75.75% (0.5% acetone fraction). Similar results were obtained
with seed extract and fractions. Egg hatching (45.73-84.16%) was also
affected significantly when eggs were directly treated with extract and
fractions of Datura leaves and seeds.