Comparative Efficacy of Different Insecticides Against Cucurbit Fruit Fly (Bactrocera cucurbitae) on Bottle Gourd (Lagenaria siceraria) in Sarlahi District, Nepal

Abstract

The present investigation was conducted to evaluate the comparative efficacy of different Insecticides against cucurbit fruit fly, Bactrocera cucurbitae in Bottle Gourd laid out at farmer's field in Sarlahi district. The research was designed under RCBD with 6 treatments (T1 = Spinosad @ 200ml/ha, T2 = Dichlorovos 76% EC @2ml/litre water, T3 = Lambda cyhalothrin 5% EC @ 1-2 ml/litre water, T4 = Jholmal @10ml/ litre water, T5 = Multineem (Azadirachtin 0.03%) @ 10ml/ litre water and T6 = Control (water spray) and 3 replications accommodating 12 plants in each plot. The insecticides were applied as first, second, and third sprays at pre-set, post-set, and harvest stage of Bottle Gourd in 10 days intervals between each spray and data collection being done on 3 rd , 7 th , and 10 th day after each spray. The results showed significant variation for studied traits. The maximum number of fruit fly per plant was 8.40 (10DAS-III) during the experiment. Cucurbit fruit flies preferred young fruits and flowers for oviposition and the results obtained high pre-set damage of 43.85% (10DAS-I) and post-set damage of 68.14% (10DAS-II). The highest fruit infestation was 52.41% & 53.71% based on number and weight respectively under control treatment. Under Spinosad treatment, the lowest insect population (1.33 at 3DAS-III) was obtained with least pre-set damage, post-set damage, and minimum fruit infestation of the insect by number (27.29%) and weight (25.90%) followed by Dichlorovos and Lambda-cyhalothrin for similar traits. While, Jholmal and Azadirachtin were inferior in controlling the fruit fly population and reducing the infestation at pre-set, post-set, and harvest stage. However, Azadirachtin and Lambda-cyhalothrin were on par in terms of post-set damage (46.32% and 47.50%), respectively. The results revealed that Spinosad is the best bio-pesticide against Cucurbit fruit fly in Bottle Gourd with Dichlorovos and Lambda-cyhalothrin next in order while Jholmal and Azadirachtin offered a better quality of fruits and higher yield in Bottle Gourd. While chemical insecticides may seem effective for short term, we must opt to use eco-friendly pesticides/botanicals such as Spinosad, Jholmal and Azadirachtin for pest management and thus further study is required to explore the comparative efficacy of bio-pesticides/botanicals against chemical insecticides for fruit fly management in Bottle Gourd.