Bolser Robin C, Hay Mark E
Institute of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell Street, Morehead City, NC 28557, USA, , , , , , US.
Oecologia. 1998 Aug;116(1-2):143-153. doi: 10.1007/s004420050573.
We tested whether grazing by the specialist beetle Galerucella nymphaeae (Coleoptera: Chrysomelidae) induced resistance to herbivory in the water lily Nuphar luteum macrophyllum (Nymphaeaceae) using both the specialist beetle and the generalist crayfish Procambarus clarkii (Decapoda: Cambaridae). For 2 months, we allowed natural densities of beetles to develop on control plants of Nuphar, while removing beetles every 2-3 days from adjacent plants that were paired by location within our field site. By the end of the 2-month manipulation, beetle grazing had damaged twice as much leaf surface on control plants as on removal plants (30.6% vs. 14.2%, respectively). We then offered tissues from control and removal plants to adult and larval beetles and to crayfish in laboratory assays. Increased levels of previous attack by the specialist beetle either did not affect or increased water lily attractiveness to beetles, but significantly decreased attractiveness to the generalist crayfish. Beetle larvae did not feed preferentially on control vs. removal Nuphar in assays using either immature, undamaged leaves that had not yet reached the pond surface or intermediate aged leaves that had reached the surface and experienced some beetle grazing. Adult beetles consumed significantly more immature leaf tissue from the heavily grazed controls than from the less grazed removal plants but did not discriminate between control and removal leaves of intermediate age in either feeding or oviposition preference. In contrast, generalist crayfish consumed significantly more plant tissue from the less grazed treatment than from the more heavily grazed controls. Crude chemical extracts from Nuphar strongly deterred crayfish feeding, but neither phenolic content, protein content, nor differential effects of crude extracts from control vs. removal plants explained crayfish feeding on control versus removal leaves. Our assays suggest that induced resistance to crayfish may be chemically mediated, but the particular mechanisms producing this response remain unclear. Responses may be due to defensive metabolites that degrade rapidly following extraction.
我们使用专食性甲虫黄斑长跗萤叶甲（鞘翅目：叶甲科）和广食性小龙虾克氏原螯虾（十足目：螯虾科），测试了专食性甲虫黄斑长跗萤叶甲的取食是否会诱导睡莲大叶萍蓬草（睡莲科）对食草动物产生抗性。在两个月的时间里，我们让自然密度的甲虫在萍蓬草的对照植株上生长，同时每隔2 - 3天从我们田间试验地中按位置配对的相邻植株上移除甲虫。到为期两个月的操作结束时，甲虫取食对对照植株叶片表面造成的损伤是移除甲虫植株的两倍（分别为30.6%和14.2%）。然后，我们在实验室试验中，将对照植株和移除甲虫植株的组织提供给成年甲虫、幼虫以及小龙虾。专食性甲虫先前攻击水平的增加，要么不影响睡莲对甲虫的吸引力，要么增加了这种吸引力，但显著降低了对广食性小龙虾的吸引力。在使用尚未到达池塘水面的未成熟、未受损叶片或已到达水面并经历了一些甲虫取食的中年叶片进行的试验中，甲虫幼虫在对照萍蓬草和移除甲虫的萍蓬草之间没有表现出取食偏好。成年甲虫从重度取食的对照植株上消耗的未成熟叶片组织明显多于轻度取食的移除甲虫植株，但在取食或产卵偏好上，对中年的对照叶片和移除甲虫叶片没有区分。相比之下，广食性小龙虾从轻度取食处理的植株上消耗的植物组织明显多于重度取食的对照植株。萍蓬草的粗化学提取物强烈抑制小龙虾取食，但酚类含量、蛋白质含量，以及对照植株和移除甲虫植株粗提取物的差异效应，均无法解释小龙虾对对照叶片和移除甲虫叶片的取食差异。我们的试验表明，对小龙虾的诱导抗性可能是由化学物质介导的，但产生这种反应的具体机制仍不清楚。这种反应可能是由于防御性代谢产物在提取后迅速降解所致。
