4种杀虫剂对玉米3种害虫的毒力及种子处理防治效果评价

为评价4种杀虫剂在玉米田防治灰飞虱Laodelphax striatellus、禾蓟马Frankliniella tenuicornis和玉米蚜Rhopalosiphum maidis的应用前景,采用浸苗法测定了其对3种害虫的毒力,并通过种子处理筛选对3种害虫田间防效较高的药剂。结果表明,噻虫嗪、呋虫胺和吡虫啉对灰飞虱、禾蓟马和玉米蚜具有较高毒力,LC50分别为0.14～1.10、4.24～31.01 mg/L和0.80～7.49 mg/L,氟啶虫酰胺的毒力最低,对3种害虫的LC50分别为84. 55、222.72 mg/L和44.81 mg/L。采用种子处理的方式施药后,各药剂处理组玉米出苗率与对照组无显著差异,安全性较高;播种后30 d,20%氟啶虫酰胺种子处理悬浮剂对灰飞虱、禾蓟马的防效均在75%以上,播种后40 d,70%噻虫嗪种子处理可分散粉剂对灰飞虱防效最高,其次为20%氟啶虫酰胺种子处理悬浮剂、8%呋虫胺悬浮种衣剂和600 g/L吡虫啉悬浮种衣剂;播种后50 d(玉米抽雄期)调查,20%氟啶虫酰胺种子处理悬浮剂对玉米蚜防治效果可达92.1%,表现出较高的防治效果,噻虫嗪、呋虫胺、吡虫啉防治效果略低,但均在70%以上,能有效防治玉米蚜的为害。综上,氟啶虫酰胺、噻虫嗪、呋虫胺和吡虫啉均适合用于防治玉米田灰飞虱、禾蓟马和玉米蚜3种害虫。

Toxicity and seed treatment control effects of four insecticides against three maize pests

In order to evaluate the application prospect of four insecticides against Laodelphax striatellus, Frankliniella tenuicornis and Rhopalosiphum maidis on maize, the toxicity of the four insecticides to the pests were determined by maize seedlings-dipped method, and then their control efficiency were evaluated by field tests. Toxicity tests showed that thiamethoxam, dinotefuran and imidacloprid had higher toxicity to L.striatellus, F.tenuicornis and R.maidis, with the LC50 values of 0.14-1.10 mg/L, 4.24-31.01 mg/L and 0.80-7.49 mg/L, respectively. The toxicity of flonicamid was the lowest to L.striatellus, F.tenuicornis and R.maidis, with the LC50 values of 84.55 mg/L, 222.72 mg/L and 44.81 mg/L, respectively. Field efficacy test showed that there was no significant difference in the emergence rate of corn between the treatments and the control, and it was safe to the crop. The treatment of flonicamid 20% FS at maize seedling stage had highest control effect on L.striatellus and F. tenuicornis, with the control efficacies above 75%. After sowing 40 d, thiamethoxam 70% WS had the highest control effect on L.striatellus, followed by flonicamid 20% FS, dinotefuran 8% FSC and imidacloprid 600 g/L FSC. The control efficacy of flonicamid 20% FS on R.maidis was 92.1% after sowing 50 d (staminate stage of corn), which was higher than that of thiamethoxam, dinotefuran and imidacloprid, but all above 70% and all the four insecticides can effectively control the damage of corn aphid. In conclusion, flonicamid, thiamethoxam, dinotefuran and imidacloprid all have good application prospects and are suitable for the control of L.striatellus, F.tenuicornis and R.maidis in maize field.