Toxic and sub toxic effects of Bacillus Thuringiensis svar. kurstaki Toward Ectomyelois Ceratoniae (Lepidoptera: Pyralidae).

The objective of this study is twofold: first, to determine the toxicity of Bacillus thuringiensis var. kurstaki (Bt) on the first larval instar of Ectomyelois ceratoniae, and second, to study its deferred effect on other biological parameters, such as the development and reproduction of this pest. The treated larvae were then paired, and the following concentrations were utilized: The experiment was conducted using a series of concentrations, ranging from 0.25 grams per liter (250 parts per million [ppm]) to 2 grams per liter (2000 ppm). Six pairs of Petri dishes were utilized for each concentration, with the number of eggs laid being recorded. Subsequent to this, the number of eggs that hatched following their incubation period was tallied. In the context of Bt svar. kurstaki, the variable of interest is the rate of larval mortality. The results demonstrated a robust and positive correlation between the administered doses and the adjusted mortality of the larvae across a range of bioinsecticide exposure times. The five Bt svar. kurstaki concentrations utilized resulted in a corrected mortality of E. ceratoniae first instar larvae, exhibiting variation between a minimum of 50.78% and a maximum of 97.92%. It has been demonstrated that Bacillus thuringiensis var. kurstaki becomes increasingly toxic to larvae following exposure to the biopesticide. Therefore, the median lethal concentration (LC50) of Bt svar. kurstaki for E. ceratoniae larvae, calculated at concentrations of 250, 500, 1,000, 1,500, and 2,000 parts per million (ppm), exhibited an inverse proportionality to the different lethal times. Conversely, the Bt treatment exhibited a marked decrease in female insects' reproductive rate and egg viability. Consequently, the BT exerted a deleterious effect on the growth and reproductive parameters of E. ceratoniae.