Ostergård Hannah, Hambäck Peter A, Ehrlén Johan
Department of Botany, Stockholm University, SE-106 91 Stockholm, Sweden.
Ecology. 2007 Dec;88(12):2959-65. doi: 10.1890/07-0346.1.
Oviposition sites of phytophagous insects should correlate with plant traits that maximize survival of the progeny. Plants, on the other hand, should benefit from traits and developmental patterns that complicate oviposition decisions. In the antagonistic interaction between plant and pre-dispersal seed predator the time lag between egg laying and seed development may allow for abortion of fruits in plants, potentially reducing fitness loss through predation. We studied the perennial herb Lathvrus vernus and the beetle pre-dispersal seed predator Bruchus atomarius in Sweden to determine the fitness consequences of nonrandom fruit abortion in the plant and oviposition patterns of the beetle. The beetle had a sophisticated ability to locate fruits with high probability of retention, partly by fruit position and phenology but also by some additional unidentified cue. Mortality of eggs was density dependent, but still the egg-laying pattern was clumped. We found no defensive strategy in the plant; instead the predictable fruit abortion pattern was associated with decreased plant fitness. We discuss how interactions may pose simultaneous selection pressures on plant and insect traits and how life history traits and other selective forces may shape the adaptive outcome of the interaction in plant and insect, respectively.
植食性昆虫的产卵地点应与能使后代存活率最大化的植物性状相关。另一方面，植物应受益于那些使产卵决策复杂化的性状和发育模式。在植物与种子传播前的捕食者之间的对抗性相互作用中，产卵与种子发育之间的时间间隔可能会使植物的果实流产，从而有可能减少因捕食造成的适合度损失。我们在瑞典研究了多年生草本植物春巢菜和种子传播前的甲虫捕食者豌豆象，以确定植物中果实非随机流产以及甲虫产卵模式的适合度后果。这种甲虫具有一种复杂的能力，能够以较高概率定位具有较高留存可能性的果实，部分是通过果实位置和物候特征，但也通过一些其他未确定的线索。卵的死亡率取决于密度，但产卵模式仍然是聚集的。我们在植物中未发现防御策略；相反，可预测的果实流产模式与植物适合度降低相关。我们讨论了这种相互作用如何可能对植物和昆虫的性状同时施加选择压力，以及生活史性状和其他选择力量如何可能分别塑造植物和昆虫相互作用的适应性结果。
