Journal of Taiwan Agricultural Research

Author:Hsin-Shun Lai

Abstract:

    The study was conducted to evaluate effects of fiv ratios of eight organophosphates in adult food on the mortality of the melon fl, Bactrocera cucurbitae (Coquillett). Higher ratios of insecticides resulted in increasing melon flymortalities. As there were no non-insecticide food baits provided for melon flys choice (no-choice test), baits mixed with dimethoate caused higher mortalities com-pared to other insecticides tested on the melon flies.Dimethoate baits at a concentration of 1/2000 (v/v) killed approximately 85% of the fliestested at 24 h, while it caused 98% mortality at 48 h. On the other hand, the profenofos bait was least effective to the melon fl. In a non-insecticide bait provided together with an insecticide bait to the melon fliesfor choice (choice test), dimethoate bait still caused the highest mortalities to the fliestested, while fenitrothion and malathion baits resulted in the lowest ones. Melon flymortalities were higher in the no-choice tests than the choice. Phenthoate bait maintained the highest residual toxicity among all of the baits tested. This bait at a concentration of 1/100 after two weeks of exposure in the greenhouse still caused over 80% of mortalities. Collectively, this study showed that chlorpyrifos, dimethoate, fenthion, phenthoate and prothiofos elicited high toxic-ity to the melon flywhile incorporated into the adult food, and were potential to be considered as the insecticide additives in melon fly baits.

Key words:Bactrocera cucurbitae, Organophosphates, Baits

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