Journal of Applied Microbiology (2000) 89, 309-316

M. Porcar and P. Caballero (2000)
Molecular and insecticidal characterization of a Bacillus thuringiensis strain isolated during a natural epizootic
Journal of Applied Microbiology 89 (2), 309-316
Abstract: A new Bacillus thuringiensis strain belonging to the serovar aizawai was isolated from a dead larva of the lepidopteran Mythimna loreyi collected in a corn crop in Spain during a natural epizootic. This strain, which was named Leapi01, was compared with the kurstaki and aizawai strains isolated from Dipel^® and Xentari^®, by electron microscopy, SDS-PAGE, plasmid pattern, PCR and insecticidal activity. This strain showed similar morphological and biochemical characteristics to the standard strains. The content in cry genes of Leapi01 was analysed with a set of general and specific primers recognizing most of the cry genes reported to date. DNA amplification was obtained with primers corresponding to six genes and, to clearly determine the identity of the genes, the amplified fragments were sequenced and corresponded to cry1Aa, cry1Ab, cry1Ca, cry1Da, cry2Ab and cry1Ia. However, the proteins encoded by two of these genes, Cry2 and Cry1I, were not detected in the SDS-PAGE of the purified parasporal bodies. The insecticidal activity of Leapi01 was determined by bioassays against two Lepidoptera species, Helicoverpa armigera and Spodoptera littoralis, that were found to be very susceptible to Leapi01 purified crystals. Since two of the cry genes identified in Leapi01 appear to be silent, other factors may be involved in the toxicity of the strain. As a result of this study, the potential of Leapi01 as biological control agent is discussed, with special emphasis on the high toxicity and relatively broad spectrum activity compared with two B. thuringiensis strains that are the active ingredients of commercial preparations commonly used as bioinsecticides.
(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): Primitivo Caballero

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Acantholeucania loreyi	Maize/corn (Zea mays)	Spain (continental)
Bacillus thuringiensis var. aizawai (entomopathogen)			Spain (continental)