The Artificial Diet For Eocanthecona Furcellate(Wolff) And Its Predatory Efficiency

Eocanthecona furcellata(Wolff)is an important predatory natural enemy of many agricultural pests.In this paper,Response-Surface Design(RSD)was used to select the optimal artificial diet for Eocanthecona furcellate(Wolff),and the dry powder of Bactrocera dorsalis(Hendel),bovine liver,egg yolk,hemolymph of Antheraea pernyi and honey were chose as the main components.Functional response method was used to evaluate the predatory efficiency of E.furcellata fed on artificial diets to the larvae of Tenebrio molito(L.)and Spodoptera litura(Fabricius).The main results are as follows:1.Selection of the artificial diet for E.furcellataA total of 31 groups of artificial diets were designed with RSD in Statistical Analysis System(SAS),the dry powder of Bactrocera dorsalis(Hendel),bovine liver,egg yolk,hemolymph of Antheraea pernyi and honey were chose as the main components,royal jelly,trehalose,yeast powder,choline chloride,ascorbic acid,streptomycin sulfate,fresh milk and cabbage juice were chose as the subsidiary components.Results showed that more than90% of the artificial diet formula could make E.furcellata complete its generation development,but there were significant differences in the developmental duration and survival rate of nymphs,adult body weight,percentage of ovipositing female adults and product between E.furcellata fed on artificial diets(the treatment)and those reared by the larvae of T.molito(the control).The developmental time of E.furcellata nymph fed on artificial diet No.18 and No.26 were 17.00 d and 17.68 d respectively,which was close to the control group,17.39 d.However,the developmental rate of E.furcellata nymph was prolonged obviously in other treatment groups,and the significance development delay was observed in the fifth instar nymph.The survival rate of E.furcellata nymph fed on artificial diet No.2,No.4,No.5,No.9,No.13,No.17,No.19 and No.25 were above 50%,higher than the control,19.09%,while the nymph survival rate were lower than 30% in the treatmentwith diets No.6 to No.8,No.11,No.12,No.14 to No.16,No.23,and No27 to No.31.Eggs laid by E.furcellata adult females were between 86.63 to 101.87 when fed on the diets No.16,No.18,No.20,and No.26,but was significantly lower than the control,292.47..Compared with the control group,the preoviposition period was significantly prolonged,the sex ratio of female to male fluctuated greatly,and the percentage of ovipositing female decreased in the treatment groups,but the hatching rate of offspring was close to the control.According to the four key biological indexes,such as the developmental period and survival rate of the nymph,the percentage of egg laying female adults,the amount of eggs laid,and the hatching rate of the offspring eggs,the artifical diets No.18,No.20 and No.26 were relatively good.and diet No.18 was the optimal one.Variance analysis showed that the contents of dry powder of B.dorsalis powder,bovine liver and egg yolk had significant effects on the nymphs survival rate and egg laying capacity of female adults.2.Predatory efficacy of E.furcellata fed on artifical dietsFunctional response method was used to evaluate the predatory efficiency of E.furcellata(the third instar nymph,the fifth nymph and female adults)to the larvae of T molitor and S.litura(the third instar larvae and the fifth instar larvae).Results showed that Functional response of E.furcellata in different developmental stage to the larvae of T molitor and S.litura was fitted well with Holling II model.The number of prey consumed increased with prey density and the development of E.furcellata.Female adults showed the strongest predatory capacity,followed by the fifth instar nymph,then the third instar nymph.The maximum daily predation of female adult of E.furcellata was 14.6 fed on artificial diets,which was little lower than the control,17.6.But the maximum daily predation of the fifth instar nymph of E.furcellata was close to that of the control.However,the nymph attack rate of E.furcellata fed on artificial diets was significantly higher than that of the control group,which meant that the predation efficiency of E.furcellata fed on artificial diets to the larvae of S.litura was improved.