成蟲飼料添加新尼古丁類與抗生素類殺蟲劑對瓜實蠅[Bactrocera cucurbitae (Coquillett)] (Diptera: Tephritidae)之毒效測試

Abstract

The melon fly, Bactrocera cucurbitae (Coquillett), is an important pest of cucurbit crops. Application of poison baits is the major strategy recommended by the government for the melon fly control. This study was conducted to screen out effective neonicotinoids and antibiotic insecticides with no-choice (only a poisoned bait being provided) and choice (a non-poison bait being provided together with a poisoned bait) tests in the laboratory. It helps in providing important information for the selection of low-toxic insecticide additives for melon fly baits that reduces the harmful effects imposed on the environments and the farmers, as well as increasing the insecticide options to reduce the development of insecticide resistance. Results of no-choice tests showed that the neonicotinoidsthiamethoxam, clothianidin, and dinotefuran, and the antibiotic insecticides-emamectin benzoate, spinetoram, and spinosad added to the adult foods elicited high lethal effects to the melon flies. These selected neonicotinoids resulted in approximately 50% mortalities which was a little lower than 60% mortalities caused by the selected antibiotic insecticides. However, both insecticide groups all made the melon fly mortalities reached 95% at the end of 72-h experimental periods. Results also showed that the rates of melon fly mortalities induced by emamectin benzoate and spinetoram were faster than that induced by spinosad, a registered insecticide additive for fruit fly food baits, and the mortality rates by the thiamethoxam, clothianidin, and dinotefuran were similar to the spinosad. Choice tests indicated that both the selected neonicotinoids and antibiotic insecticides caused limited deterrent effects, but substantial insecticidal toxicities to the melon flies. Collectively, this study suggests that the above selected insecticides and abamectin, the one with a little less lethality, deserve further investigations for their potential as effective insecticide additive in the melon fly baits.