Bulletin of Entomological Research (2007) 97, 351-357
G. Singh, P.J. Rup and Opender Koul (2007)
Acute, sublethal and combination effects of azadirachtin and Bacillus thuringiensis toxins on Helicoverpa armigera (Lepidoptera: Noctuidae) larvae
Bulletin of Entomological Research 97 (4), 351-357
Abstract: The efficacy of neem (1500 ppm azadirachtin (AI)), Delfin®WG™, a biological insecticide based on selected strain of Bacillus thuringiensis Berliner (Bt) subspecies kurstaki, and Cry1Ac protein, either individually or in combination, were examined against first to fourth instar Helicoverpa armigera (Hübner) larvae. Using an oral administration method, various growth inhibitory concentrations (EC) and lethal concentrations (LC) were determined for each bioagent. Combinations of sublethal concentrations of Bt spray formulation with azadirachtin at EC50 or EC95 levels not only enhanced the toxicity, but also reduced the duration of action when used in a mixture. The LC20 and LC50 values for Cry1Ac toxin were 0.06 and 0.22 μg ml-1, respectively. Bt-azadirachtin combinations of LC50+EC20 and LC50+EC50 result in 100% mortality. The mortality also was significant in LC20+EC20 and LC20+EC50 mixtures. These studies imply that the combined action is not synergistic but complimentary, with azadirachtin particularly facilitating the action of Bt. The Bt spray-azadirachtin combination is more economical than combinations that involve isolating the toxic protein, as the Bt spray formulations can be combined in a spray mixture with neem. These combinations may be useful for controlling bollworm populations that have acquired resistance to Bt as they may not survive the effect of mixture. Azadirachtin may be useful as a means of reducing the endotoxin concentrations in a mixture, to promote increased economic savings and further reduce the probability of resistance development to either insect control agent.
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Link to article at publishers website
Database assignments for author(s): Opender Koul
Research topic(s) for pests/diseases/weeds:
control - general
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
formulation/storage of bioagents
Pest and/or beneficial records:
Beneficial | Pest/Disease/Weed | Crop/Product | Country | Quarant.
|
---|---|---|---|---|
Helicoverpa armigera | ||||
Bacillus thuringiensis var. kurstaki (entomopathogen) | Helicoverpa armigera | |||
Bacillus thuringiensis Cry1A-toxin (entomopathogen) | Helicoverpa armigera |