(103) Assay Card

General Information
Summary Growth of H. armigera larvae stunted by kalata B1 containing diet
Condition H. armigera larvae were raised on an artificial diet based on haricot beans. Wheat germ was suspended in water and boiled for 20 min to inactivate the wheat germ lectin before incorporation into the diet. Larvae were raised from neonates to the midsecond (electron microscopy) and early-third (light microscopy) instar stage of development, before they were starved for 6 h and transferred to test diets supplemented with kalata B1 peptide [0.13% (wt/vol) or 0.24% (wt/vol)] or linear kalata B1 [0.24% (wt/vol)]. The cyclic kalata B1 and linear B1 (Fig. 1) were prepared as described (32). The control diet contained casein in place of the inhibitor. Each larva was placed in a clean 1.5-ml microfuge tube containing 330 mg of diet and was maintained at 25 1C, 16:8 h (light/dark). After 16 h, the larvae were weighed, and the amount of fecal pellets produced and diet remaining was recorded. Three larvae were used for each diet. The bioassay was performed three times.
Result Control larvae doubled in size over the 16-h bioassay. Larvae on the diet with the highest concentration of kalata B1 [0.24% (wt/vol)] did not grow, consumed very little, and produced few fecal pellets. Larvae exposed to the lower concentration of kalata B1 were only 16% larger than larvae fed on the highest concentration of kalata B1 even though they had consumed about half the diet and produced an intermediate amount of fecal pellets relative to the other two groups.
AssayType Insecticidal

References
Barbeta BL, Marshall AT, Gillon AD, Craik DJ, Anderson MA (2008) Plant cyclotides disrupt epithelial cells in the midgut of lepidopteran larvae Proc Natl Acad Sci U S A 105:1221-1225

Cross-references
Proteins Assayed kalata B1