Prider Jane, Watling Jennifer, Facelli José M
Ecology and Evolutionary Biology, School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia.
Ann Bot. 2009 Jan;103(1):107-15. doi: 10.1093/aob/mcn214. Epub 2008 Nov 10.
While invasive species may escape from natural enemies in the new range, the establishment of novel biotic interactions with species native to the invaded range can determine their success. Biological control of plant populations can be achieved by manipulation of a species' enemies in the invaded range. Interactions were therefore investigated between a native parasitic plant and an invasive legume in Mediterranean-type woodlands of South Australia.
The effects of the native stem parasite, Cassytha pubescens, on the introduced host, Cytisus scoparius, and a co-occurring native host, Leptospermum myrsinoides, were compared. The hypothesis that the parasitic plant would have a greater impact on the introduced host than the native host was tested. In a field study, photosynthesis, growth and survival of hosts and parasite were examined.
As predicted, Cassytha had greater impacts on the introduced host than the native host. Dead Cytisus were associated with dense Cassytha infections but mortality of Leptospermum was not correlated with parasite infection. Cassytha infection reduced the photosynthetic rates of both hosts. Infected Cytisus showed slower recovery of photosystem II efficiency, lower transpiration rates and reduced photosynthetic biomass in comparison with uninfected plants. Parasite photosynthetic rates and growth rates were higher when growing on the introduced host Cytisus, than on Leptospermum.
Infection by a native parasitic plant had strong negative effects on the physiology and above-ground biomass allocation of an introduced species and was correlated with increased plant mortality. The greater impact of the parasite on the introduced host may be due to either the greater resources that this host provides or increased resistance to infection by the native host. This disparity of effects between introduced host and native host indicates the potential for Cassytha to be exploited as a control tool.
虽然入侵物种在新区域可能摆脱了天敌，但与入侵区域的本地物种建立新的生物相互作用会决定它们能否成功。通过操控入侵区域物种的天敌，可以实现对植物种群的生物防治。因此，我们对南澳大利亚地中海型林地中的一种本地寄生植物与一种入侵豆科植物之间的相互作用进行了研究。
比较了本地茎寄生植物毛无根藤对引入宿主金雀儿以及同时存在的本地宿主桃金娘桉的影响。检验了寄生植物对引入宿主的影响大于对本地宿主的影响这一假设。在一项田间研究中，考察了宿主和寄生植物的光合作用、生长和存活情况。
正如预测的那样，毛无根藤对引入宿主的影响大于对本地宿主的影响。死亡的金雀儿与毛无根藤的密集感染有关，但桃金娘桉的死亡率与寄生植物感染无关。毛无根藤的感染降低了两种宿主的光合速率。与未感染的植物相比，感染毛无根藤的金雀儿光合系统II效率恢复较慢、蒸腾速率较低且光合生物量减少。寄生植物在引入宿主金雀儿上生长时的光合速率和生长速率高于在桃金娘桉上的。
本地寄生植物的感染对引入物种的生理和地上生物量分配产生了强烈的负面影响，并且与植物死亡率增加相关。寄生植物对引入宿主的更大影响可能是由于该宿主提供了更多资源，或者本地宿主对感染的抵抗力增强。引入宿主和本地宿主之间这种影响的差异表明毛无根藤有被开发为一种防治工具的潜力。
