小十三星瓢虫对苜蓿斑蚜的捕食功能反应

对小十三星瓢虫Adonia variegata(Goeze)捕食苜蓿斑蚜Therioaphis trifolii(Monell)的研究表明,其功能反应为Holling-Ⅱ型模型,方程为Na=0.967N/(1+0.0095N),捕食苜蓿斑蚜的数量随斑蚜密度增加而增大,日最大捕食量为102头。在10~25℃下,小十三星瓢虫捕食率y与温度x的关系为y=3.4x-7.9375;在25~35℃间的捕食率y与温度x的关系为y=137.08-2.25x。25℃下小十三星瓢虫捕食率最高,捕食率达79.4%。在种内干扰条件下,其捕食作用率E随天敌密度P的增加而减少,干扰反应数学模型为E=0.6063P-0.6743。随着叶片数的增多,小十三星瓢虫和斑蚜之间的距离相对增大,造成捕食率的下降。

The predatory functional response of Adonia variegata on Therioaphis trifolii

The functional response of ladybird (Adonia variegata(Goeze)) preying on spotted aphid (Therioaphis trifolii(Monell)) was analyzed. The results showed that the functional response model belonged to Holling-Ⅱtype:N_a=0.967N/(1+0.0095 N). Relationship between amount of spotted aphid preyed by ladybird and spotted aphid density showed a negativepositive accelerative curve. The daily maximum number of spotted aphid preyed by a ladybird was 102 theoretically. At the range of 10～25℃, the relationship between predation ratio(y)and temperature(x)was y=3.4x-7.9375,and at 25～35℃, y=137.08-2.25x. The predation ratio was the highest at 25℃reaching 79.4%. Under the intraspecific interference, the predation ratio(E)decreased with increase of natural enemy density(P), and the natural interference equation was E=0.6063 P~ -0.6743 . The results also showed that the relative distance between ladybird and spotted aphid prolonged with the increase of alfalfa leaves, and it would result in the decrease of predation ratio. This research will provide the scientific basis for controlling alfalfa spotted aphid by use of Adonia variegate.