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

利用苦苣菜蚜-苦苣菜蚜茧蜂混合种群系统模拟模型,通过改变种群参数、初始虫量和温度条件,探讨了蚜茧蜂产卵选择寄主龄期特性对整个种群系统行为的影响,并比较了这一特性与蜂产卵量两者的相对重要性。结果表明,蜂产卵对寄主龄期选择特性的改变可明显改变其对蚜虫种群增长影响的程度,当产卵选择特性改变,产卵量在多数情况下必须要大幅度直至成倍的增减,才能补偿其对蚜虫种群的控制作用。不过,当蜂产卵嗜好三龄、二龄、四龄若蚜时(这在蚜茧蜂中较普遍),其作用和产卵无选择性时基本相似。

A COMPUTER SIMULATION STUDY OF THE HOST INSTAR PREFERENCE OF APHIDIIDS FOR OVIPOSITION AND THE IMPACT ON APHID POPULATIONS

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.