Carlson Jane E, Harms Kyle E
Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
Biol Lett. 2007 Aug 22;3(4):405-7. doi: 10.1098/rsbl.2007.0095.
Protective floral structures may evolve in response to the negative effects of floral herbivores. For example, water calyces--liquid-filled, cup-like structures resulting from the fusion of sepals--may reduce floral herbivory by submerging buds during their development. Our observations of a water-calyx plant, Chrysothemis friedrichsthaliana (Gesneriaceae), revealed that buds were frequently attacked by ovipositing moths (Alucitidae), whose larvae consumed anthers and stigmas before corollas opened. Almost 25% of per-plant flower production was destroyed by alucitid larvae over two seasons, far exceeding the losses to all other floral herbivores combined. Experimental manipulation of water levels in calyces showed that a liquid barrier over buds halved per-flower alucitid egg deposition and subsequent herbivory, relative to buds in calyces without water. Thus, C. friedrichsthaliana's water calyx helps protect buds from a highly detrimental floral herbivore. Our findings support claims that sepal morphology is largely influenced by selection to reduce floral herbivory, and that these pressures can result in novel morphological adaptations.
保护性花部结构可能会因花食草动物的负面影响而进化。例如，水萼片——由萼片融合形成的充满液体的杯状结构——可能通过在芽发育期间将其淹没来减少花食草动物的侵害。我们对一种具水萼片的植物金黄猪笼草（苦苣苔科）的观察发现，芽经常受到产卵蛾（多翼蛾科）的攻击，其幼虫在花冠开放前会取食花药和柱头。在两个季节里，多翼蛾科幼虫破坏了近25%的单株花卉产量，远远超过了所有其他花食草动物造成的损失总和。对萼片中水位的实验操作表明，相对于无水萼片中的芽，芽上的液体屏障使每朵花上多翼蛾科的卵沉积量和随后的食草量减半。因此，金黄猪笼草的水萼片有助于保护芽免受一种极具危害性的花食草动物的侵害。我们的研究结果支持了以下观点：萼片形态在很大程度上受减少花食草动物侵害的选择影响，并且这些压力可导致新的形态适应。
