Bacillus thuringiensis increases the efficacy of bio-pesticides against eggplant shoot and fruit borer, Leucinodes orbonalis Guenee

Abstract

Brinjal shoot and fruit borer (BSFB) is a notorious pest of brinjal. This study evaluates some microbe and plant origin bio-pesticides alone or in combination with Bacillus thuringiensis var. kurstaki 5 % (Btk 5 %) in the brinjal field to combat against BSFB. We found that application of biopesticides in combination with Btk 5 % increased the control of BSFB that results increased marketable yield, gross yield, individual fruit weight compared to their application without Btk 5 %. Among the biopesticide combinations, Abamectin 1.2 % + Emamectin benzoate 1 % and Btk 5 % as well as Emamectin benzoate 1 % and Btk 5 % were potent in context to BSFB control and yield attributes. These combinations confirmed 78.04 % and 74.76 % shoot infestation control, 70.90 % fruit infestation reduction in number basis, 72.40 % and 72.18 % fruit infestation control in weight basis, 13.56 ton ha⁻¹ and 11.41 ton ha⁻¹ marketable yield, 15.59 ton ha⁻¹ and 12.37 ton ha⁻¹ gross yield, respectively. In contrast, Abamectin 1.2 % + Emamectin benzoate 1 % and Emamectin benzoate 1 % confirmed 58.18 % and 67.96 % shoot infestation control, 50.27 % and 62.06 % fruit infestation reduction in number basis, 51.86 % and 59.24 % fruit infestation control in weight basis, 9.05 ton ha⁻¹ and 9.44 ton ha⁻¹ marketable yield, 11.82 ton ha⁻¹ and 10.83 ton ha⁻¹ gross yield. These promising bio-pesticide combined with Bt also ensure more individual fruit weight compared to without Bt. These results thus illustrated that application of Btk 5 % along with bio-pesticide increases their efficacy because of the synthesis of insecticidal toxins named Cry, Vip, and Cyt by Btk 5 % that have synergistic effect with biopesticides and kill insects.