Canadian Forest Service Publications

Diagnostic biochimique de la présence d'une intoxication par Bacillus thuringiensis sérotype "H3a, 3b" chez deux lépidoptères. 1989. Valéro, J.R.; Letarte, R. Canadian Journal of Microbiology 35 : 444-449.

Year: 1989

Issued by: Laurentian Forestry Centre

Catalog ID: 14239

Language: French

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Abstract

A detailed biochemical analysis has shown that during larval development on artifical medium, the amounts of K+, Na+, and Ca2+ in the hemolymph of healthy Choristoneura fumiferana varied from 85 to 110 mg/100 mL, 29 to 33 mg/100 mL, and 4.8 to 7.3 mg/100 mL, respectively. Similar results were obtained with Malacosoma disstria. Intoxication by Bacillus thuringiensis "H3a, 3b" (B.t.) considerably modified the amounts of the cations. Thus, after 4 h, the quantity of K+ in M. disstria increased from 99 to 229 mg/100 mL and Na+ from 26.5 to 50.3 mg/100 mL while that of Ca2+ decreased from 5.8 to 1.2 mg/100 mL. Similar results were observed with C. fumiferana, but these variations occurred after 2 to 4 days of B.t. intoxication. The variations detected during the bacillosis, with respect to the cationic composition of the insect hemolymph, are rapidly detectable, well before light microscope observation can confirm the presence of this intoxication. Aspartate aminotransferase, alanine aminotransferase, α=hydroxybutyrate dehydrogenase, and isocitrate dehydrogenase activity fluctuated very slightly in the hemolymph of either healthy or bacillosed larvae of the two insects under study. These results suggest that it is possible to diagnose biochemically the presence of a B.t. intoxication in lepidopteran forest pests following treatments by this biological insecticide for their control.