RESIDUAL TOXICITY OF INSECTICIDES, OILS AND SURFACTANTS AGAINST SPIRALLING WHITEFLY,Aleurodicus (dispersus Russell
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Date
2001-08-06
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK BANGALORE
Abstract
Investigations were carried out on the different developmental stages of
spiralling whitefly, Aleurodicus dispersus on the toxicity and bio-efficacy of
fifteen insecticides, seven oils and four surfactants and their combinations in
the greenhouse and under field conditions.
Triazophos (0.06%) and dimethoate (0.05%) have shown excellent
performance both under laboratory and field conditions and proved to be
ovicidal, ovipositional deterrent and effective against the most resistant pupal
stage of the pest and recorded an adult mortality of 75 per cent at 1 5 DAT in
laboratory conditions and 90 per cent egg mortality and around cent per cent
mortality of other stages under field conditions. Dichlorvos (0.105%) and
monocrotophos (0.045%) were the next best chemicals against different stages
of the pest.
Among the seven oils used with four surfactants, fish oil insecticidal soap
at 2.50 per cent proved to be better which persisted for a longer time and
recorded 60 per cent adult mortality at 15 DAT under laboratory conditions.
The next best oils were neem oil (1%) and cotton seed oil (1.0%). Under field
condition also fish oil insecticidal soap was effective recording around 70, 60,
55 and 80 per cent reduction of egg masses, nymphs, pupae and adults,
respectively at the end of 1 5 DAS. Among the plant products neem oil proved
better registering around 65, 55, 40 and 75 per cent reduction in egg masses,
nymphs, pupae and adults, respectively at 15 DAS.
The combination of promising insecticides with oils at their half dose was
excellent in triazophos or dimethoate combination with FOIS as compared to
triazophos and dimethoate alone under laboratory conditions. But triazophos
and dimethoate recorded higher reduction of the pest population as compared
to their combination with oils under field conditions. Further, the insecticides
were found to be cheaper as compared to the oils.
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