Efficacy of Biopesticides for controlling major pests of Cucumber (Cucumis sativus L.) in Surkhet District, Nepal

This study evaluated the efficacy of biopesticides against major insect pests of cucumber (Cucumis sativus L.) in Lekbeshi, Surkhet, Nepal. A randomized complete block design experiment was conducted with four treatments: Beauveria bassiana (1 ml/L), Bacillus thuringiensis (Bt) (2 ml/L), Jholmol (1:5 concentration), and an untreated control. After the third spray, B. bassiana reduced red pumpkin beetle populations from 1.4 to 0.4 insects per plant, while Bt reduced fruit fly populations from 2.8 to 1.6 insects per plant, compared to the control (4.2 to 2.2). At 60 days after transplanting, Bt-treated plants were significantly taller (137.45 cm) than control plants (111.28 cm). Fruit damage was lowest in Bt-treated plots (1.8% and 0.69 kg damage weight) compared to the control (3.8% and 0.69 kg). While yield attributes showed no significant differences, total yield was highest in B. bassiana-treated plots (35.58 t/ha) compared to the control (17.8 t/ha). Economic analysis revealed that B. bassiana treatment had the highest benefit-cost ratio (4.19), followed by Bt (2.9), control (2.8), and Jholmol (2.3). These findings suggest that biopesticides, particularly B. bassiana and Bt, can effectively manage major cucumber pests while improving yield and economic returns, offering a sustainable alternative to chemical pesticides in subtropical regions.