Differential activity and activation of Bacillus thuringiensis insecticidal proteins in diamondback moth, Plutella xylostella.
Whole-crystal preparations from strains HD-1 and HD-133, activated Cry1Ab and Cry1C toxins as well as Cry1Aa, Cry1Ac, Cry1D, and Cry2Aa protoxins were tested for toxicity to 2nd-instar larvae of the diamondback moth, Plutella xylostella. Mortality data recorded after 2 and 5 days provided different results that were related to differential rates of solubilization, activation, and degradation of insecticidal crystal proteins. The two most active proteins are Cry1Ab and Cry1C, which are both present in HD-133. The Cry1Ab protoxin is activated within 2 days, whereas activation of the Cry1C protoxin occurs between 2 and 5 days. HD-133 is more active than HD-1 immediately after infection and remains toxic over 5 days owing to the sequential activation of its crystal components. Solubility properties of crystals and rates of activation of protoxins influence the overall toxicity of HD-1 and HD-133 to the diamondback moth.
Monnerat
R
R
Cenargen-EMBRAPA, SAIN-Parque Rural CP, 02372 CEP, 70770-970 Brasilia DF, Brazil.
Masson
L
L
Brousseau
R
R
Pusztai-Carey
M
M
Bordat
D
D
Frutos
R
R
D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism*; D001427:Bacterial Toxins; D003460:Crystallization; D004731:Endotoxins / Q000378:metabolism*; D006460:Hemolysin Proteins; D002479:Inclusion Bodies / Q000737:chemistry; D007814:Larva / Q000378:metabolism; D007928:Lethal Dose 50; D009036:Moths / Q000254:growth & development / Q000378:metabolism*; D010572:Pest Control, Biological; D013997:Time Factors
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis