Predatory functional response of Coccinella septempunctata to Megoura crassicauda

【Objective】The predatory functional response of different stages of Coccinella septempunctata to Megoura crassicauda was explored,which would provide scientific basis for control of M.crassicauda by means of C.septempunctata in field.【Method】Under laboratory conditions,C. septempunctata in different stages and different density gradie-nts of the 3^rd instar nymphs of M.crassicauda were prepared. By controlling single variable method,the functional response and search effect of C.septempunctata in different stages to the 3^rd instar nymphs of M.crassicauda were studied,intraspecial interference response of adult C.septempunctata and intraspecial interference response at the same ratio were also studied,as well as the effect of different temperature and space size on predation of adult C.septempunctata.【Result】The results showed that the functional response of the 1^st to the 4^th instar nymphs and adults of C. septempunctata to M. crassicauda fitted well with the Holling-Ⅱ model. The predation efficacy(a'/T_h) of the different insect states of C.septempunctata on M. crassicauda was 4^th instar larvae,adult females,adult males,3^rd instar larvae,2^nd instar larvae and 1^st instar larvae in descending order. Larval predation increased with age,4^th instar larvae was the highest,and female adults were higher than male adults. The search effect of each stage of C. septempunctata on M. crassicauda decreased with increasing prey density. The effect of the adult C. septempunctata's density on the predatory effect of M. crassicauda was consistent with the Hassell model. There was intraspecific interference among adult C. septempunctata,and as their own density increased,interference increased and average predation decreased. The mathematical model for the intraspecific disturbance response of C. septempunctata was E=0.7954P^-0.882. Under the condition of a certain number of C. septempunctata in different spaces,the predation amount of C. septempunctata decreased with the increase of space,which indicated that the increase of space affected C. septempunctata's preying. Under the conditions of constant light and humidity,the predation of adult C. septempunctata increased with the increase of temperature,and decreased when the temperature exceeded 32 ℃,but the predation capacity of adult C. septempunctata remained high at 38 ℃.【Conclusion】C. septempunctata has a strong predatory ability on M. crassicauda,with a wide range of temperature adaptations,and space size has some effects on the predation amount.