Toxicity of Bacillus Thuringiensis Var. San Diego and Var. Kurstaki HD290I to Leaf Beetles (Coleoptera: Chrysomelidae)
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Authors
Pifer, D. Andrew
Issue Date
1992
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Bacillus thuringiensis (Bt) is a soil dwelling bacterium that produces
various insecticidal crystal proteins (ICPs) (Bauer 1990). It has been
demonstrated that some beetles can develop a resistance to Bt isolates
(Whalon, et al. 1992). A research project is underway that will attempt to
discover which mode of ICP action: ingestion, processing, or binding, most
greatly controls resistance. I was responsible for developing a reproducible
bioassay and calculating the median lethal dose (LD50) for Cottonwood Leaf
Beetles (CLB), Chrysomela scripta and Colorado Potato Beetles (CPB),
Leptinotarsa decemlineata (Say) to Bt var. san diego (sd) and Bt var. kurstaki (k)
HD290i. The objectives of these experiments were three-fold: (1) to
experimentally determine if a CLB colony could become Bt-resistant through
graduall y increasing exposure to Bt-sd toxin, (2) to see if cross resistance to
another Bt isolate (Bt-k) occurs in Bt-sd resistant strains, and (3) to calculate
the effectiveness of crystal Bt-k vs. solubilized Bt-k. The results show that CLB
do form a significant level of Bt-sd resistance, some cross resistance occurs in
CLB but not in CPB, and solubilized toxin appears to be more lethal than
crystallized.
Description
vii, 30 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.