药剂处理有蚜烟叶对异色瓢虫选择行为的影响

【背景】植物挥发物的特性之一就是可变性，多种胁迫因子，如光照、干旱等，均可导致植物挥发物组分与含量发生改变，进而影响天敌搜索猎物的行为。【方法】本试验以杀虫剂作为影响植物挥发物的胁迫因子，利用“Y”形嗅觉仪观测8种杀虫剂处理有蚜烟叶后对异色瓢虫显明变种、显现变型和二斑变型选择行为的影响。【结果】异色瓢虫对健康无蚜烟叶无明显趋性；与洁净空气相比，异色瓢虫对无药剂处理有蚜烟叶的选择率为70％～74％。在氧乐果处理后，异色瓢虫显明变种、显现变型和二斑变型对有蚜烟叶的选择率分别为32％、36％和34％，氟虫腈·高氯处理后，其选择率分别为36％、38％和36％，多杀霉素处理后，其选择率分别为40％、42％和38％，异色瓢虫对这3种杀虫剂处理有蚜烟叶的趋性明显降低；吡虫啉处理后，其选择率分别为64％、62％和60％，啶虫脒处理后，其选择率分别为62％、68％和66％，这2种杀虫剂可略微降低瓢虫的趋性反应；氯氰菊酯处理后，其选择率分别为80％、82％和80％，氯氟氰菊酯处理后，其选择率均为78％，氟氯氰菊酯处理后，其选择率分别为76％、78％和76％，这3种杀虫剂可增强瓢虫的趋性反应。【结论与意义】杀虫剂可能会对烟草挥发物的组分和含量产生影响，但不同的杀虫剂影响效果不同。

Search behavior responses of Harmonia axyridis (Pallas) to tobacco exposed to insecticides and aphids

Background ] Stress can lead to plant volatiles components and contents to change. This change can increase or reduce the searching behavior of natural enemies. Method] In this experiment, tobacco leaves infested by aphids were first exposed to eight insecticides as the stress factor. Then the search behavior response of Harmonia axyridis （Pallas） var. spectabilis, H. axyridis （ Pal- las） ab. Conspicua and H. axyridis （ Pallas ） ab. Bimaculata were measured using a Y-tube olfactometer. Result ] The results showed that the three varieties of H. axyridis did not show any preference when exposed to intact tobacco leaves. H. axyridis however selected tobacco leaves infested by Myzus persicae at a rate of 70% - 74%. When infested tobacco was sprayed with omethoate, H. axyridis varieties selected at rates of 32% , 36% and 34% ; When exposed to fipronil ＋ perchloric, the rates were 36% , 38% and 36% ; When tobacco leaves was sprayed with spinosad, the rates were 40% , 42% and 38%. The preferences of the ladybirds to to- bacco leaves exposed to these three insecticides were weak obviously. Two insecticides, imidacloprid and acetamiprid only slightly affected the search behavior of ladybirds （ rates varying between 60% and 68% ）. When infested tobacco was sprayed with beta- cypermethrin, El. axyridis varieties selected at rates of 80%, 82% and 80% ; When exposed to lambda-cyhothrin, the rates were all 78% ; When exposed to cyfluthrin, the rates were 76% , 78% and 76%. The preferences of the ladybirds to tobacco leaves exposed to these three insecticides were strong. Conclusion and significance ] Insecticides can probably change plant volatiles components and contents, but different insecticides have different effects.