Agrawal A A
Department of Entomology and Center for Population Biology, University of California, Davis, California 95616-8584, USA.
Am Nat. 2001 May;157(5):555-69. doi: 10.1086/319932.
Herbivory has many effects on plants, ranging from shifts in primary processes such as photosynthesis, growth, and phenology to effects on defense against subsequent herbivores and other species interactions. In this study, I investigated the effects of herbivory on seed and seedling characteristics of several families of wild radish (Raphanus raphanistrum) to test the hypothesis that herbivory may affect the quality of offspring and the resistance of offspring to plant parasites. Transgenerational effects of herbivory may represent adaptive maternal effects or factors that constrain or amplify natural selection on progeny. Caterpillar (Pieris rapae) herbivory to greenhouse-grown plants caused plants in some families to produce smaller seeds and those in other families to produce larger seeds compared with undamaged controls. Seed mass was positively associated with probability of emergence in the field. The number of setose trichomes, a putative plant defense, was higher in the progeny of damaged plants in some families and lower in the progeny of damaged plants in other families. In a field experiment, plant families varied in their resistance to several herbivores and pathogens as well as in growth rate and time to flowering. Seeds from damaged parent plants were more likely to become infested with a plant virus. Although herbivory on maternal plants did not directly affect interactions of offspring with other plant parasites, seed mass influenced plant resistance to several attackers. Thus, herbivory affected seed characters, which mediated interactions between plants and their parasites. Finally, irrespective of seed mass, herbivory on maternal plants influenced components of progeny fitness, which was dependent on plant family. Natural selection may act on plant responses to herbivory that affect seedling-parasite interactions and, ultimately, fitness.
食草作用对植物有诸多影响，从光合作用、生长和物候等主要过程的变化，到对抵御后续食草动物及其他物种相互作用的影响。在本研究中，我调查了食草作用对几个野生萝卜（Raphanus raphanistrum）家族种子和幼苗特征的影响，以检验食草作用可能影响后代质量以及后代对植物寄生虫抗性的假说。食草作用的跨代效应可能代表适应性母体效应，或对后代自然选择产生限制或放大作用的因素。与未受损伤的对照相比，毛虫（粉蝶）对温室种植植物的食草作用使一些家族的植物产生较小的种子，而另一些家族的植物产生较大的种子。种子质量与田间出苗概率呈正相关。一些家族中受损植物后代的刚毛状毛状体数量（一种假定的植物防御机制）较多，而另一些家族中受损植物后代的则较少。在田间试验中，不同植物家族对几种食草动物和病原体的抗性、生长速率以及开花时间各不相同。受损亲本植物的种子更易感染植物病毒。尽管母体植物遭受的食草作用并未直接影响后代与其他植物寄生虫的相互作用，但种子质量影响了植物对几种攻击者的抗性。因此，食草作用影响了种子特征，而种子特征介导了植物与其寄生虫之间的相互作用。最后，无论种子质量如何，母体植物遭受的食草作用都会影响后代适合度的组成部分，而后代适合度取决于植物家族。自然选择可能作用于植物对食草作用的反应，这些反应会影响幼苗与寄生虫的相互作用，并最终影响适合度。
