Selection and characterization of Mexican strains of Bacillus thuringiensis active against four major lepidopteran maize pests.

Bohorova, N and Maciel, A M and Hoisington, D A (1996) Selection and characterization of Mexican strains of Bacillus thuringiensis active against four major lepidopteran maize pests. Entomophaga, 41 (2). pp. 153-165. ISSN 0013-8959

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Abstract

In order to isolate novel delta-endotoxins from Bacillus thuringiensis, a total of 426 native isolates (in varying numbers for each pest) were screened against four major maize pests: Helicoverpa zea, Spodoptera frugiperda, Diatraea grandiosella and Diatraea saccharalis. Spore-crystal complexes from the isolates were integrated into semi-artificial diets of each pest and mortality was assessed 7 days after treatment. A total of 25 isolates were selected on the basis of highest larval mortality against at least one insect species. There was no correspondence of the most toxic isolates when tested against the four different insect species. Most of the 25 selected isolates caused higher toxicities against all four pests than the standard strain HD-1, regardless of not achieving 100% mortality in any bioassay. H. zea demonstrated the highest level of mortality (96%) and was susceptible to the largest number of isolates (98). None of the other insect species were found susceptible at levels greater than 60%. All the selected active strains were isolated from stored grain dusts (except for LBIT-167), and had bipyramidal crystals with Cry I-like proteins. Most isolates also formed an associated square (cubic) inclusion, with Cry II-like proteins according to SDS-PAGE analysis of their parasporal bodies. The most active isolates will be subjected to further studies, in order to identify putative novel genes to be expressed in transgenic maize.

Item Type:	Article
Divisions:	UNSPECIFIED
CRP:	UNSPECIFIED
Uncontrolled Keywords:	Bacillus thuringiensis, Helicoverpa zea, Spodoptera frugiperda. Diatraea grandiosella, Diatraea saccharalis, mortality, maize.
Subjects:	Others > Maize
Depositing User:	Mr. Thimma Reddy
Date Deposited:	16 Mar 2012 10:07
Last Modified:	16 Mar 2012 10:07
URI:	http://oar.icrisat.org/id/eprint/5748
Official URL:	http://dx.doi.org/10.1007/BF02764243
Projects:	UNSPECIFIED
Funders:	UNSPECIFIED
Acknowledgement:	[NOTE: D. A. Hoisington is presently with ICRISAT (Patancheru)]
Links:	Author

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