Journal of Insect Behavior (2008) 21, 407-421
Gurmeet Singh, Pushpinder J. Rup and Opender Koul (2008)
Selective feeding of Helicoverpa armigera (Hübner) and Spodoptera litura (Fabricius) on meridic diet with Bacillus thuringiensis toxins
Journal of Insect Behavior 21 (5), 407-421
Abstract: Laboratory experiments were conducted to evaluate the behavior of Helicoverpa armigera (Hübner) and Spodoptera litura (Fabricius) larvae on meridic diet with different concentrations of Bt spray formulation Delfin or isolated Cry1Ac protein or the foliage and bolls from transgenic cotton, Bollgard hybrid RCH-317 Bt. Both insect species selectively fed on nontreated diet compared with the diet treated with Delfin. While H. armigera exhibited concentration response with Cry1Ac, this protein did not affect S. litura larvae. In general Helicoverpa selected diet with low concentrations (EC20 and EC50 levels) of Cry1Ac compared with higher concentrations of Cry1Ac. In order to develop appropriate management strategies, a thorough understanding of the behavioral mechanisms leading to the responses of insects to the proteins in transgenic varieties is required. Thus, based on results of the insects fed individually on the leaf discs or bolls from transgenic cotton plants alone or under choice situation with meridic diet revealed that H. armigera larvae preferred meridic diet to transgenic leaves or bolls expressing Cry1Ac protein. H. armigera larvae preferred meridic diet to plant material; more than 70% larvae were seen on the meridic diet, and average larval weight gain was in the range of 121.7-130.5 mg. However, in case of S. litura the larvae showed no significant discrimination between meridic diet and the leaf discs. In fact more than 60% larvae preferred leaf discs for feeding, though Cry1Ac expression in leaf discs was in the range of 0.9-2.18 μg/g. Thus differences in behavioral response could potentially impact the level of efficacy of crop cultivars that have been genetically engineered to produce these proteins.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Opender Koul
Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution
