甲氨基阿维菌素苯甲酸盐对稻纵卷叶螟的室内毒力测定及田间药效

目的]筛选防治稻纵卷叶螟的高效、安全药剂和施用方法,为水稻安全生产及科学用药提供依据.方法]在室内测定5％甲氨基阿维菌素苯甲酸盐水分散粒剂（简称甲维盐WG）和1.8％阿维菌素EC对稻纵卷叶螟3龄幼虫的毒力效果;田间药效试验设5％甲维盐WG 150.0、187.5、225.0 g/ha和1.8％阿维菌素EC 750.0 mL/ha处理,以空白为对照,调查各处理对稻纵卷叶螟的杀虫效果和保叶效果.结果]5％甲维盐WG对稻纵卷叶螟3龄幼虫具有较高的毒力,其致死中浓度（LC50）为0.5013 mg/L,低于1.8％阿维菌素EC（1.6282 mg/L）.田间药效试验结果表明,5％甲维盐WG对稻纵卷叶螟幼虫具有较好的速效性和持效性,每公顷用药187.5～225.0g,药后3d的杀虫效果为77.67％～81.33％、保叶效果为60.01％64.17％;药后7d的杀虫效果为89.38％92.17％、保叶效果为82.94％～85.02％;药后14d的杀虫效果为87.16％～89.50％、保叶效果为81.29％～84.00％,且对水稻安全.结论]5％甲维盐WG可作为稻纵卷叶螟化学防治的高效、安全药剂在水稻生产中推广应用,在稻纵卷叶螟1～2龄发生高峰期,每公顷用药187.5～225.0 g对水750 kg喷雾一次,即可达到理想的防治效果.

Toxicity determination and field control effect of emamectin benzoate WG against Cnaphalocrocis medinalis Guenee

Objective]The present experiment was conducted to screen some pesticides with high efficacy and security and determine their application method in order to provide references for rice safety production and its scientific pharmacy.Method]The toxicity effects of 5％ emamectin benzoate WG and 1.8％ abamectin EC on the 34 instar larvae of Cnaphalocrocis medinalis were tested.Four treatments were designed with blank as control,5％ emamectin benzoate WG 150.0,187.5,225.0 g/ha and 1.8％ abamectin EC 750.0 mL/ha to investigate their effects on killing insects and protecting leaves.Result]The results of toxicity determination in laboratory indicated that LC50 of 5％ emamectin benzoate WG was 0.5013 mg/L to 3rd instar larvae of Cnaphalocrocis medinalis,which was lower than that of 1.8％ abamectin EC （1.6282 mg/L）.The results of control tests in fields showed that 5％ emamectin benzoate WG had better rapid and persistent effects on controlling instar larvae.When it was applied by 187.5 to 225 g/ha,the population was decreased by 77.67％ to 81.33％ with the efficacy of leaf protection being 60.01％ to 64.17％ after three days; the population was decreased by 89.38％ to 92.17％ with the efficacy of leaf protection being 82.94％ to 85.02％ after 7 days; the population was decreased by 87.16％ to 89.5％ with the efficacy of leaf protection being 81.29％ to 84.00％ after 14 days.Additionally 5％ emamectin benzoate WG was safe on rice.Conclusion]The 5％ emamectin benzoate WG had better rapid and persistent effects on controlling instar larvae,which could be extended and applied in rice production.In peak time of the 1-2 instar larvae of Cnaphalocrocis medinalis,the appropriate mist spray should be 187.5-225.0 g/ha of 5％ emamectin benzoate WG with 750 kg/ha of water per hectare.