The Monitoring Of The Resistance Of Melon Fly To Pesticides And The Effects Of Several Pyrethroids On Its Oviposition Behavior

Melon fly, Bactrocera cucurbitae, is a destructive insect of cururbit and fruits, which has inserted serious impact on the vegetable production in Guangxi province. In this paper, we monitored the resistance level of the melon fly field population against the common control agent in Nanning, and studied the effects of several pyrethroids on the oviposition behavior of melon fly. Provide basic data for control the resistance of melon fly, at the same time, provide scientific guidance for use repellent in control melon fly. The results are follows:1. By using residual film, we conducted resistance monitoring for the melon fly field population in three different areas in Nanning. The resistant ratios of the melon fly field population against eight common control agents were between0.98and4.35, which suggested that the melon fly in Nanning has not formed resistance against these agents. Specifically, the resistant ratio of the melon fly field population in Dingdun, Tanluo against bifenthrin was3.66, which implied that the population was in the sensitive declined stage. The resistant ratios of the melon fly field population in Wutan against emamectin-benzoate and cyhalothrin were4.35and4.20respectively, which also indicated that the population was in the sensitive declined stage.2. The toxic and repellent oviposition effects of ten pyrethroids on adult of melon fly were determinated by impregnation method. The LC50values of that pyrethrodis were between187.05mg/L and442.14mg/L, and The Median Repellent Oviposition Concertration (RO50) were between6.99mg/L and45.10mg/L. The results showed that pyrethroids had poisoning on melon fly at high concentration, and got repellent oviposition effect at low concertrations. Cyhalothrin, deltamethrin, cypermethrin, cyfluthrin, and fenpropathrin showed stronger repellent oviposition effect against melon fly than others pyrethroids, which RO50values were between6.99mg/L and9.84mg/L. 3. The eggs and oviporus of melon fly in non-treated pumpkin blocks more than in treated pumpkin blocks, and reduce with the series of concentration in choice test and non-choic test condition. The numbers of eggs in treated pumpkin blocks were2.5-38.8times for non-treated in choice test, in72mg/L, the oviposition repellent rate of enpropathrin, decamethrin and cypermethrin were more than90%, like the result of observed oviporus, the best effect of oviposition repellent was cypermethrin. In non-choice test condition, the highest oviposition inhibitory rate from cyfluthrin, the rates were74.77%、93.58%and98.39%with the series of concentration, the effect of inhibition in5pyrethroids was best.4. The Y track olfactometer bioassays,5pyrethroids compared with ck, the numbers of adult female of melon fly which made choice repectively6-10, compared with profenofos, the numbers of melon fly which made choice were10-14and3-5, the numbers of female melon fly which made choice difference were no significantly, but profenofos compared with ck, the numbers of choice ck were13-16, the other were3-4, significantly different to others. The female adult of melon fly showed no rejected in olfactometer bioassays, that shows effects of5pyrethroids on repellent and inhibitory oviposition, was not olfactometer bioassays to melon fly.5. Under non-choice test condition, studied learning behavior of melon fly which contacted5pyrethroids with different days and times. Melon fly which went through cyhalothrin, decamethrin, cyfluthrin and enpropathrin, the number of eggs in treated pumpkin blocks were1-10, and8-28in non-treated pumpkin blocks, those difference no significant, no signs to habituation; Melon fly which went through cypermethrin expressed habituation, the number of eggs of melon fly which went through were not signficant for melon fly which didn’t undergo. Treated pupas of melon fly by5pyrethroids, altermate went through pyrethroids after emergence, discover the melon fly which went through decamethrin showed induction of preference, the eggs of melon fly were5-9in treated pumpkin blocks, and9-15in non-treated pumpkin blocks, difference no significant.