A COMPUTER SIMULATION STUDY OF THE HOST INSTAR PREFERENCE OF APHIDIIDS FOR OVIPOSITION AND THE IMPACT ON APHID POPULATIONS
蚜茧蜂产卵对寄主龄期的选择与其对蚜虫种群影响大小的计算机模拟研究

A computer simulation study of the host instar preference of aphidiids for oviposition and the impact of these parasites on their host aphid populations was performed with a simulation model of experimental mixed, population of Hyperomyzus lactucae-Aphidius sonchi. By varying the relevant population parameters, inital population density and structure as well as temperature, the effect of the characteristics of host instar preference of the parasite for oviposititon on the aphid was investigated. In addition, the relative importance of patterns of host instar preperence and the parasite's realized fecundity was evaluated. The simulation results showed that the impact of a parasite on its host aphid populations may be violently changed u its pattern of host instar preference is shifted. When the pattern of host instar prefernce is changed, fecundity of the parasite must be greatly decreased or increased (up to several-fold) to realize the same impact in most circumstances. How ever,preference of third, second and fourth instars,which is characterisitics of many aphidiids, exhibits more or less the same effect as that of non-preference.