Research On Screening Of The Insecticides And Their Application Technique Against Melon Fly, Bactrocera Cucurbitae (Diptera: Tephritidae)

The melon fly Bactrocera cucurbitae (Coquillett) (Diptera:Tephritidae), is a major pest on cucurbitaceous vegetables, and has caused serious economic losses. Chemical control is one of the main controlling measures against melon fly, and the effective pesticides as well as scientific and reasonable application technique are significant for sustainable control on melon fly. The bioassay methods and field efficacy trials were used in this paper for assessing and screening the poison reagent against the adult, the mature larvae and pupae of melon fly, and the oviposition repellent against of the adult of melon fly. A set of application Technique of chemical control based on the incidences of melon fly, characteristics of crop growth and features of pesticides were studied out to support the integrated management on the fly. The results as follows:1. Screening pesticides for melon fly control in the laboratoryThe toxic effects of 24 pesticides on adult of melon fly were evaluated by residual film method. The result demonstrated that profenofos, nitenpyram, phoxim, emamectin benzoate and bifenthrin had high toxicity against the adult of melon fly, with the LC50 values of 0.2649,0.3306,1.0638,1.5616 and 2.8974 mg/L, respectively.The oviposition deterrent effects of 14 pesticides on the adult of melon fly were determined by fruit spraying method. The result indicated that azadirachtin and chlorpyrifos had strong deterrent effects on the fly, with the oviposition deterrent rates reaching 100%.The toxic effects of 14 pesticides on the pupae and mature larvae of melon fly were determined by immersion method. The result showed that azadirachtin, matrine, Abamectin and emamectin benzoate all have high toxicity on the pupae and mature larvae of melon fly, with the LC50 values of 0.0058,40.598,129.357,122.173mg/L against pupae, and 0.0092, 0.1961,1.8803,3.2526 mg/L against mature larvae, respectively.2. The control effect of pesticides on melon fly in field trialsThe result of the field trials demonstrated the control effects of profenofos at the doses of 133.3-200 mg.a.i.L-1, nitenpyram at the does of 20-33.3mg.a.i.L-1 and azadirachtin at the doses of 9.375 g.a.i.ha -1 were up to 83.33%,87.78% and 93.33%, respectively, at 5d after 3 times application.3. The application technique of pesticides for controlling melon flyProfenofos and nitenpyram were effectively on control the adult of melon fly by spraying method during bitter gourd growth period at the dose of 133.3-200 mg.a.i.L-1 and 20-33.3 mg.a.i.L-1, respectively.During flowering period, the young fruits were effectively protected to avoid damage from melon fly by spraying Azadirachtin to the bitter gourd's female flowers at the dose of 9.375 g.a.i.ha-1, and bagging fruit with PE plastic bag after flower withers.Azadirachtin got the control effects over 96.67% against the pupae and mature larvae of melon fly at the doses of 5-10 mg.a.i.L-1 and 2.5-5 mg.a.i.L-1 by soil spraying method, respectively.