Bacillus thuringiensis cry3Ca1 protein is toxic to the Colorado potato beetle, Leptinotarsa decemlineata (Say)

• Published in: Biotechnology progress 2001-03, Vol.17 (2), p.211-216
• Main Authors: HAFFANI, Yosr Z, CLOUTIER, Conrad, BELZILE, Francois J
• Format: Article
• Language: English
• Subjects: Animals; Bacillus thuringiensis; Bacillus thuringiensis - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - isolation & purification; Bacterial Proteins - toxicity; Bacterial Toxins; Base Sequence; Biological and medical sciences; Biological control; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Cloning, Molecular; Coleoptera - growth & development; Control; Cry3Ca1 protein; cry3Ca1 toxin; Curculionidae; d-Endotoxin; DNA Primers; Electrophoresis, Polyacrylamide Gel; Endotoxins - genetics; Endotoxins - isolation & purification; Endotoxins - toxicity; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Hemolysin Proteins; insecticidal proteins; insecticides; Larva - drug effects; Larva - growth & development; Leptinotarsa decemlineata; Lethal Dose 50; Miscellaneous; Mission oriented research; Phytopathology. Animal pests. Plant and forest protection; Protozoa. Invertebrates; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - isolation & purification; Recombinant Fusion Proteins - toxicity
• ISSN: 8756-7938; 1520-6033
• DOI: 10.1021/bp000150d

We expressed the wild-type cry3Aa3 and cry3Ca1 Bacillus thuringiensis genes, which code for insecticidal proteins, in an Escherichia coli expression system. Highly purified preparations of the soluble delta-endotoxins were used to perform comparative bioassays with third-instar larvae of the Colorado potato beetle (CPB). Acute mortality data showed that Cry3Ca1 (LD(50) = 320.1 ng) was 2-fold more toxic than Cry3Aa3 (LD(50) = 672.9 ng). We also compared the chronic effects of sublethal doses of these toxins by measuring the consumption of untreated foliage and monitoring survival and development for 6 days after intoxication. No significant additional mortality was recorded, but we found that surviving larvae fed Cry3Ca1 consumed foliage at a slower rate than the larvae fed Cry3Aa3, suggesting more damage to their digestive epithelium. This study, the first assessment of the toxicity of cry3Ca1 in third-instar CPB, suggests cry3Ca1 will prove useful for the control of this important insect pest.