Toxicity of Chemical Insecticides and Neem Oil on Cucurbit Fruit Fly Bactrocera cucurbitae

Abstract

Background: The popular vegetable sweet gourd (Cucurbita moschata) is cultivated throughout Bangladesh. However, its yield is low owing to the severe infestation by fruit fly Bactrocera cucurbitae. This study investigated the toxicity of chemical insecticides and neem oil on fruit flies infesting sweet gourd. Methods: The repellency of adult fruit flies and larvae and the body weight and mortality of the larvae of the fruit fly were evaluated using three chemical insecticides- Karate 2.5 EC (cyhalothrin), Ripcord 10 EC (cypermethrin) and Shobicron 425 EC (profenofos Q+cypermethrin) and neem oil (azadirachtin). Result: The repellency rate of the fruit fly larvae varied from 20.0±0.0 to 86.7±6.7% and that of the adult fly from 13.3±6.7 to 73.3±6.7%; Shobicron 425 EC, at 2000 ppm, exhibited the best results in both the cases. The treatments negatively affected the weight of larvae compared to the control, where Shobicron 425 EC caused the lowest weight (7.8±0.2 mg). The insecticides at 24, 48 and 72 h after treatment demonstrated toxic effects on the larvae, where the LC50 values ranged from 742.5 (550.4-1060.5) to 2476.3 (2150.6-2954.7) ppm at 72 h after treatment. On the whole, Shobicron 425 EC demonstrated better efficacy than the other insecticides against fruit flies.