农田景观格局对苜蓿蚜虫及捕食性天敌的影响

The effect of farmland landscape pattern on the population dynamics of alfalfa aphids and predatory natural enemies

以宁夏回族自治区石嘴山市的平罗县和惠农区、吴忠市的同心县和红寺堡区共计4个不同景观区域为试验样区,探索了农田景观格局对苜蓿蚜虫和捕食性天敌的影响,分析了不同区域景观尺度下苜蓿蚜虫与捕食性天敌种群间关系。结果表明:在4个区域中,捕食性天敌的优势种群为瓢虫、捕食性蝽和蜘蛛,总数为56.5头/20复网。在同心县、红寺堡区,捕食性天敌数量与苜蓿、玉米所占比例的相关性不明显;但在平罗县、惠农区,捕食性天敌数量与玉米所占比例呈正相关,与苜蓿所占比例呈负相关。同心县、红寺堡区的苜蓿蚜虫种群数量高于平罗县和惠农区。

Four areas of diff erent landscapes from Pingluo and Huinong of Shizuishan and Tongxin and Hongsibu of Wuzhong were selected to study the impacts of farmland landscape patterns on predatory natural enemies and alfalfa aphids. And the relationship between alfalfa aphids and predatory natural enemy populations at different regional landscape scales was analyzed. The results showed that: in the four areas, the dominant populations of predatory natural enemies were ladybugs, predatory bugs, and spiders, with a total of 56.5 individuals per 20 nettings. In Tongxin county and Hongsibu District, the proportion of neither alfalfa nor maize significantly correlated with the number of predatory natural enemies. However, in Pingluo County and Huinong District, the size of natural enemies was positively correlated with the proportion of maize(p<0.05) and negatively with the proportion of alfalfa(p<0.05). The population of alfalfa aphid in Hongsibu district and Tongxin county was higher than that in Pingluo County and Huinong district. Our study shows that acomplex farmland landscape can increase the abundance of predators, which is beneficial to the biological control against aphids and other pests in alfalfa fields.