ABSTRACT

The potential for the newly established ichneumonid Mastrus ridens (Horstmann) to provide biological control of codling moth, Cydia pomonella (L.), was simulated by incorporating different rates of parasitism into previously published life tables for a univoltine codling moth population on unsprayed apple trees in Nelson, New Zealand. Simulations over eight years were conducted using high and low initial codling moth densities, as occur respectively on neglected apple trees and commercially managed orchards. Life table simulations without M. ridens served as control treatments for comparison with simulations that included various rates of parasitism by each of the estimated three annual generations of the parasitoid. Based on the percentage parasitism recorded in New Zealand and the international literature, M. ridens is projected by the models to provide a valuable reduction of codling moth populations on neglected host trees in Nelson and thereby reduce the numbers of immigrant adult moths invading commercial apple orchards. In contrast, the codling moth is maintained at such extremely low densities within commercial apple orchards growing fruit for export that M. ridens is projected to make only a small contribution to parasitism within the orchard. These simulation results confirm the validity of the rationale for the introduction of M. ridens to New Zealand, which aimed to reduce the numbers of immigrant codling moths arriving in orchards from highly infested and neglected host trees in the wider environment.

摘要

新建立的 ichneumonid Mastrus ridens (Horstmann) 对苹果蠹蛾Cydia pomonella (L.)提供生物控制的潜力是通过将不同的寄生率纳入先前发表的未喷洒苹果树上的单叶苹果蠹蛾种群的生命表来模拟的在新西兰纳尔逊。使用高和低初始苹果蠹蛾密度进行了八年多的模拟，分别发生在被忽视的苹果树和商业管理的果园上。没有M.ridens 的生命表模拟作为对照处理，用于与模拟比较，其中包括估计的三年寄生蜂的每一代寄生率的不同寄生率。根据新西兰和国际文献中记录的寄生百分比，模型预测M. ridens可有效减少尼尔森被忽视的寄主树上的苹果蠹蛾种群，从而减少入侵商业苹果园的移民成年蛾的数量. 相比之下，苹果园商业苹果园中的苹果蠹蛾的密度极低，这种苹果园种植出口水果，以至于M.ridens预计只会对果园内的寄生产生很小的贡献。这些模拟结果证实了将M.ridens引入新西兰的理由的有效性，其目的是减少在更广泛的环境中从高度侵染和忽视的寄主树到达果园的移民苹果蠹蛾的数量。