防治水稻秧田二化螟持效性药剂的筛选

Selection of persistent insecticides for control of Chilo suppressalis in rice seedling stage

采用Potter喷雾塔法和饲料涂药法分别测定了9种常用杀虫剂对二化螟4龄幼虫和初孵幼虫的室内毒力。结果表明:两种生测方法测定的9种药剂对二化螟的室内毒力顺序基本一致,阿维菌素和氯虫苯甲酰胺毒力最高,氟铃脲、醚菊酯、毒死蜱和稻丰散次之,杀虫单、三唑磷和丙溴磷相对较差。以氯虫苯甲酰胺、阿维菌素和毒死蜱为代表,采用不同剂量喷雾处理稻苗,分期接种蚁螟进行持效性观察发现,喷施20%氯虫苯甲酰胺悬浮剂1∶5 000倍液,可以维持在14 d内接种蚁螟无侵入危害,而用高剂量1∶1 000倍液处理稻苗后,28 d内接种二化螟的死亡率仍达到100%,不能侵入危害;喷施1.8%阿维菌素乳油1∶1 000倍液仅在7 d内接种蚁螟无侵入危害,使用高剂量1∶500倍液处理后,延长至14 d内无侵入危害;40%毒死蜱乳油1∶1 000倍液处理后7 d的防效仅为84.3%,使用高剂量1∶300倍液处理,7 d内无侵入危害,14 d的防效仍为89.5%。讨论分析认为,氯虫苯甲酰胺和阿维菌素的持效期较长,使用高剂量处理可以进一步延长其持效期。因此,生产上在不产生药害和经济许可的情况下,可以使用高剂量氯虫苯甲酰胺和阿维菌素作为秧苗的"送嫁药",更好地防治一代水稻螟虫,并避免本田过早用药干扰天敌种群的建立。

The toxicities of 9 commonly used insecticides against the 4th-instar larvae and neonates of Chilo suppressalis were tested by Potter Tower Spraying and Residues on Artificial Diet, respectively. The results showed that abamectinn and chlorantraniliprole were higher in toxicity to C. suppressalis, and followed by hexaflumuron, ethofenprox, chlorpyrifos and phenthoate, but monosultap, triazophos and profenofos were lower. Then, the three insecticides, chlorantraniliprole, abamectin, chlorprifos, were selected as representatives to treat rice seedlings for checking their persistent effect on the neonates inoculated in time course. The results showed that treatment with 5 000 times dilution of 20% chlorantraniliprole SC could keep the rice seedlings from infestation for 14 days, and high doses （ 1 000 times dilution）could keep for 28 days. One thousand time dilution of 1.8% abamectin EC could keep no infestation for only 7 days, which could be extended to 14 days when 500 times dilution was used. The persistent control effect of 40% chlorprifos EC was poorest of the three insecticides. Only 84.3% in 7 days was observed when 1 000 times dilution was applied. However, the corresponding control effect could be enhanced to 100% ,89.5% by using 300 times dilution. It was concluded that chlorantraniliprole and abamectin had good persistent control effect,which could be further enhanced by the use of high doses. Thus,under the prerequisite for no phytotoxicity,high doses of these two insecticides were suggested for the control of the first generation of C. suppressalis by handling rice seedlings before transplant to enhance the control effect and minimize the following field insecticide sprays.