The Biology And Functional Response Of Encarsia Formosa(hymenpotera: Aphelindae) Parasitized Trialeurodes Ricini(hemiptera: Aleyrodidae)

Encarsia formosa Gahan was used widely in the world to control whiteflies in greenhouse because of its outstanding reproduction and host-feeding ability. However, disadvantages such as the high-cost and difficult to control the timing of natural enemies release that limited the further development of traditional biological control methods. However, the development of “banker bean plant system” brings us to a new stage of biological control of pests. Thus, in this research I focused on the theoretical basis of “castor bean banker plant system” to survey the biology parameters and functional response of E. formosa parasitized Trialeurodes ricini(Misra).Experimental results showed that:1. From the no-choice and choice experiments of E. formosa parasitized different instars of T. ricini, the results showed that E. formosa can successfully oviposit and host-feeding on all instars of T. ricini nymphs. However, the instars of host can affect the number of parasitism and host-feeding, moreover, can also affect the developmental time of E. formosa.(1) E. formosa can feed on all four instars of host, but the number of host-fed isvaried with host instars. The no-choice and choice test showed the same trendof host-feeding number, i.e. E. formosa would feed more young stages of hostnymphs than old ones.(2) E. formosa can oviposit in all instars of host, but shows a preference of thefourth instar.(3) E. formosa can complete development in all instars of host. However, when E.formosa parasitized the fourth instar of hosts, the developmental time was theshortest, and the eclosion rate was the highest.2. We researched the longevity of E. formosa under different food condition. Results showed that E.formosa can only survive two day without food. While, provided host or 10% honey can significant extend its longevity to 10.8 d and 4.9 d.3. The experiment of E. formosa offspring parasitized the fourth instar of hosts indicated that the parasitism tended to increase, but there was no significant difference between F1 and F2 generations.4. Results of logistic regression indicated that both of the host-feeding and parasitism functional response of E. formosa on fourth instar of T. ricini nymphs are of type Ⅱ. The estimated parameters of the host-feeding functional response indicated the attack rate a = 0.1497, the handle time Th = 0.2394; The parasitism functional response parameters are a = 0.2269, Th = 0.3258.