昆虫病原线虫对烟苗的保护效果

小地老虎Agrotis ypsilon是危害烟草的重要害虫.为了实现该害虫的绿色防控,本研究测定了小地老虎幼虫对不同食物(小白菜、蕹菜、人工饲料和麸皮)取食的偏好性,评价添加鲜叶类诱食剂时昆虫病原线虫Steinernema carpocapsae All粉剂、S.feltiae SN虫尸剂、绿僵菌Metarhizium anisopliae和化学农药敌杀死(溴氰菊酯)对小地老虎的防控而实现对移栽期烟苗的保护效果.结果表明,尽管不同时间不同食物吸引的小地老虎幼虫数量有差异,但是这些幼虫对鲜叶类蔬菜(小白菜和蕹菜)具有偏好性.当每株烟苗存在2头小地老虎4龄幼虫时,未添加幼虫诱食剂的情况下,昆虫病原线虫粉剂处理后的烟苗死亡率为56.7％,显著低于绿僵菌处理的74.2％、昆虫病原线虫虫尸剂处理70.0％和对照78.3％,但高于敌杀死(溴氰菊酯)处理的烟苗死亡率37.5％;添加诱食剂后,昆虫病原线虫粉剂处理后烟苗的死亡率为40.8％,显著低于绿僵菌62.5％和昆虫病原线虫虫尸剂67.6％处理和对照62.5％,但与敌杀死(溴氰菊酯)处理的烟苗死亡率39.2％,差异不显著.当每株烟苗存在3头小地老虎4龄幼虫时,不论是否添加小地老虎幼虫诱食剂,昆虫病原线虫粉剂处理后的烟苗死亡率显著低于绿僵菌、昆虫病原线虫虫尸剂处理和对照,但与敌杀死(溴氰菊酯)处理的烟苗死亡率差异不显著.同样,添加幼虫诱食剂后,昆虫病原线虫粉剂处理的烟苗死亡率为36.7％,显著低于未加入小地老虎幼虫诱食剂的处理71.7％.因此,烟苗周围存在2头或3头小地老虎4龄幼虫的情况下,S.carpocapsae All线虫粉剂对刚移栽烟苗具有明显保护作用,在烟苗周围添加小地老虎幼虫诱食剂能显著降低烟苗的被危害率,为烟田小地老虎幼虫防控提供了有效的方法.

Protection efficacy of tobacco seedings by entomopathogenic nematodes

Black cutworm Agrotis ypsilon is an important pest in tobacco field. For the green development of tobacco industry, Steinernema carpocapsae All in vermiculite, Steinernema feltiae SN in Galleria cadavers, Metarhizium anisopliae or chemical insecticide (deltamethrin), together with cut fresh weeds as attractant food around tobacco seeding, were used to protect young tobacco seedings from black cutworm larvae in tobacco field. Meanwhile, the preference of black cutworm larvae to different foods (Chinese cabbage, water spinach, artificial medium and wheat bran) was determined. Although larval percentages attracted by foods varied with time, Chinese cabbage and water spinach were selected by most of larvae. When two black cutworm larvae were present in a tobacco seeding, without addition of attractant food, damage rate 56.7% of tobacco seedings treated with S. carpocapsae All in vermiculite was significantly lower than those treated with M. anisopliae 74.2%, S. feltiae SN in Galleria cadavers 70.0% and control 78.3%, but significantly higher than that treated with deltamethrin 37.5%; with the addition of the attractant food, damage rate 40.8% of tobacco seedings treated with S. carpocapsae All in vermiculite was significantly lower than those treated with M. anisopliae 63.5%, S. feltiae SN in Galleria cadavers 67.6% and control 62.5%, but not significantly different from that treated with deltamethrin 39.2%. When three black cutworm larvae were present in a tobacco seeding, without or with the addition of the attractant food, damage rate of tobacco seedings treated with S. carpocapsae All in vermiculite was significantly lower than those treated with M. anisopliae, S. feltiae SN in Galleria cadavers and control, but not significantly different from that treated with deltamethrin. Meanwhile, damage rate 36.7% of tobacco seedings treated with S. carpocapsae All in vermiculite, with the addition of the attractant food, was significantly lower than that 71.7% without the addition of the attractant food. These results indicated that S. carpocapsae All in vermiculite markedly protected tobacco seedings from black cutworm larvae at a density of three or three larvae per seeding, and attractant food around tobacco seeding significantly decreased damage rates of seedings by black cutworm larvae, providing an effective method for control of A. ypsilon larvae in tobacco field.