SUSCEPTBiLTIY OFTHE INDIAN MEAL MOTH, PLODIA INTERPUNCTELLA HB (PYRALIDAE- LEPIDOPTERA) TO ENTOMOPATHOGENIC BACTERIA IN THE LABORATORY

Abstract

The effects of three Bacillus thuringiensis based­ formulations (Delfin®, MVPII® and Agerin®) were evaluated against larvae (18-days-old) of Plodia inte1punctel/a Hubner, after 72 h following infection by using diet contamination method. Bioassays were conducted to estimate baseline levels of susceptibility of the larvae to each formulation and to calculate concentrations to be mixed with the rearing medium that would produce about 50, 75 and 95% mortalities. Feeding larvae on media contaminated with each of the three lethal concentrations of the three formulations for 72 h induced the following consequences:

I. Decrease in the rate of 02 -consumption. 2. Induction of somewhat different effects on the level of respiratory quotient. 3. Induction of several variable changes in the haemolymph total carbohydrate and protein contents. 4. Reduction in the haemolymph total lipid content. 5. Induction of several changes in the electrophoretically separated bands of haemolymph protein fractions, either in the pattern or in the densities of the corresponding bands. 6. Production of several numbers of newly formed protein bands characteristic to each single lethal concentration of each bacterial formulation. 7. Absence of any bacteriostatic effect of cell-free haemolymph of infected larvae.