Tikkanen O-P, Niemelä P, Keränen J
Department of Biology, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland e-mail:
Faculty of Forestry, University of Joensuu, PO Box 111, FIN-80101 Joensuu, Finland, , , , , , FI.
Oecologia. 2000 Mar;122(4):529-536. doi: 10.1007/s004420050976.
A generalist feeding strategy is common among eruptive insect herbivores but the ultimate reasons for a generalist strategy are not clear. Although generalist insect herbivores are able to complete their life cycle on several species of host plants, there is wide variation in the performance of individuals grown on different hosts. We examined whether different populations of Operophtera brumata are adapted to use the host species which is locally most abundant, and how the host plant affects growth and development of the insect. We reared two allopatric populations (eastern Finland, Prunus padus; south-west Finland, Quercus robur) on four species of host plants (Pr. padus, Populus tremula, Q. robur, Salix phylicifolia) from neonate larvae to the adult stage and measured the growth and development of individuals and the timing of adult hatching. The performance of both populations was best on Pr. padus, and the south-western population, originally on Q. robur, was well adapted to this host. The host affected the growth of females more than that of males. The host plant had an unexpected effect on hatching times of the adults. Individuals grown on the original host hatched in normal synchrony, i.e. males 6-7 days before females; but on alternative hosts this synchrony was disturbed. As is common in eruptive, capital-breeding generalist moths where female fecundity is linked to weight, host quality is critical for the flightless females of O. brumata. We suggest that in a heterogeneous environment the disturbing effect of alternative host plants on adult emergence may decrease the population density and growth rate compared to the potential maximum in a homogeneous environment.
多食性取食策略在爆发性昆虫食草动物中很常见，但这种策略的根本原因尚不清楚。尽管多食性昆虫食草动物能够在多种寄主植物上完成其生命周期，但在不同寄主上生长的个体表现差异很大。我们研究了不同种群的冬尺蠖是否适应利用当地最丰富的寄主物种，以及寄主植物如何影响这种昆虫的生长和发育。我们将两个异域种群（芬兰东部，稠李；芬兰西南部，欧洲栎）从新生幼虫饲养到成虫阶段，以四种寄主植物（稠李、欧洲山杨、欧洲栎、柳叶菜柳）为食，并测量了个体的生长发育情况以及成虫羽化时间。两个种群在稠李上的表现最佳，原本以欧洲栎为食的西南部种群也很好地适应了这种寄主。寄主对雌性生长的影响大于雄性。寄主植物对成虫羽化时间产生了意想不到的影响。在原生寄主上生长的个体正常同步羽化，即雄性比雌性早6 - 7天；但在替代寄主上，这种同步性受到了干扰。在爆发性、资本繁殖的多食性蛾类中，雌性繁殖力与体重相关，寄主质量对不会飞的冬尺蠖雌性至关重要，这是常见现象。我们认为，在异质环境中，与同质环境中的潜在最大值相比，替代寄主植物对成虫羽化的干扰作用可能会降低种群密度和增长率。
