Hoffmann Daniela, Vierheilig Horst, Riegler Petra, Schausberger Peter
Department of Applied Plant Sciences and Plant Biotechnology, Institute of Plant Protection, BOKU, University of Natural Resources and Applied Life Sciences, Peter Jordan Strasse 82, 1190, Vienna, Austria.
Oecologia. 2009 Jan;158(4):663-71. doi: 10.1007/s00442-008-1179-7. Epub 2008 Oct 24.
Most terrestrial plants live in symbiosis with arbuscular mycorrhizal (AM) fungi. Studies on the direct interaction between plants and mycorrhizal fungi are numerous whereas studies on the indirect interaction between such fungi and herbivores feeding on aboveground plant parts are scarce. We studied the impact of AM symbiosis on host plant choice and life history of an acarine surface piercing-sucking herbivore, the polyphagous two-spotted spider mite Tetranychus urticae. Experiments were performed on detached leaflets taken from common bean plants (Phaseolus vulgaris) colonized or not colonized by the AM fungus Glomus mosseae. T. urticae females were subjected to choice tests between leaves from mycorrhizal and non-mycorrhizal plants. Juvenile survival and development, adult female survival, oviposition rate and offspring sex ratio were measured in order to estimate the population growth parameters of T. urticae on either substrate. Moreover, we analyzed the macro- and micronutrient concentration of the aboveground plant parts. Adult T. urticae females preferentially resided and oviposited on mycorrhizal versus non-mycorrhizal leaflets. AM symbiosis significantly decreased embryonic development time and increased the overall oviposition rate as well as the proportion of female offspring produced during peak oviposition. Altogether, the improved life history parameters resulted in significant changes in net reproductive rate, intrinsic rate of increase, doubling time and finite rate of increase. Aboveground parts of colonized plants showed higher concentrations of P and K whereas Mn and Zn were both found at lower levels. This is the first study documenting the effect of AM symbiosis on the population growth rates of a herbivore, tracking the changes in life history characteristics throughout the life cycle. We discuss the AM-plant-herbivore interaction in relation to plant quality, herbivore feeding type and site and the evolutionary implications in a multi-trophic context.
大多数陆生植物与丛枝菌根（AM）真菌共生。关于植物与菌根真菌之间直接相互作用的研究众多，而关于此类真菌与取食地上部分植物的食草动物之间间接相互作用的研究却很少。我们研究了AM共生对一种叶螨类表面刺吸式食草动物——多食性二斑叶螨Tetranychus urticae的寄主植物选择和生活史的影响。实验在取自接种或未接种AM真菌摩西球囊霉Glomus mosseae的菜豆植株（Phaseolus vulgaris）的离体小叶上进行。让二斑叶螨雌螨在菌根植物和非菌根植物的叶片之间进行选择试验。测量了幼虫的存活和发育、成年雌螨的存活、产卵率和后代性别比，以估计二斑叶螨在这两种基质上的种群增长参数。此外，我们分析了地上部分植物的大量和微量营养元素浓度。成年二斑叶螨雌螨优先栖息和产卵于菌根小叶而非非菌根小叶上。AM共生显著缩短了胚胎发育时间，提高了总体产卵率以及产卵高峰期产生的雌性后代比例。总的来说，改善的生活史参数导致净繁殖率、内禀增长率、加倍时间和有限增长率发生了显著变化。接种植物的地上部分显示出较高的磷和钾浓度，而锰和锌的含量均较低。这是第一项记录AM共生对食草动物种群增长率影响的研究，跟踪了整个生命周期内生活史特征的变化。我们讨论了AM-植物-食草动物相互作用与植物质量、食草动物取食类型和部位以及多营养背景下的进化意义。
