Pós-graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas-SP, Brazil.
Ann Bot. 2011 May;107(6):1047-55. doi: 10.1093/aob/mcr047. Epub 2011 Mar 7.
Several animals that live on bromeliads can contribute to plant nutrition through nitrogen provisioning (digestive mutualism). The bromeliad-living spider Psecas chapoda (Salticidae) inhabits and breeds on Bromelia balansae in regions of South America, but in specific regions can also appear on Ananas comosus (pineapple) plantations and Aechmea distichantha.
Using isotopic and physiological methods in greenhouse experiments, the role of labelled ((15)N) spider faeces and Drosophila melanogaster flies in the nutrition and growth of each host plant was evaluated, as well as seasonal variation in the importance of this digestive mutualism.
Spiders contributed 0·6 ± 0·2 % (mean ± s.e.; dry season) to 2·7 ± 1 % (wet season) to the total nitrogen in B. balansae, 2·4 ± 0·4 % (dry) to 4·1 ± 0·3 % (wet) in An. comosus and 3·8 ± 0·4 % (dry) to 5 ± 1 % (wet) in Ae. distichantha. In contrast, flies did not contribute to the nutrition of these bromeliads. Chlorophylls and carotenoid concentrations did not differ among treatments. Plants that received faeces had higher soluble protein concentrations and leaf growth (RGR) only during the wet season.
These results indicate that the mutualism between spiders and bromeliads is seasonally restricted, generating a conditional outcome. There was interspecific variation in nutrient uptake, probably related to each species' performance and photosynthetic pathways. Whereas B. balansae seems to use nitrogen for growth, Ae. distichantha apparently stores nitrogen for stressful nutritional conditions. Bromeliads absorbed more nitrogen coming from spider faeces than from flies, reinforcing the beneficial role played by predators in these digestive mutualisms.
几种以凤梨科植物为食的动物可以通过提供氮素（消化共生）来促进植物营养。生活在凤梨科植物上的蜘蛛 Psecas chapoda（跳蛛科）栖息并在南美洲的 Bromelia balansae 上繁殖，但在特定地区也会出现在菠萝（菠萝）种植园和 Aechmea distichantha 上。
在温室实验中使用同位素和生理方法，评估标记（15N）蜘蛛粪便和黑腹果蝇对每种宿主植物的营养和生长的作用，以及这种消化共生的季节性变化。
蜘蛛对 Bromelia balansae 的总氮贡献了 0.6±0.2%（干季）至 2.7±1%（湿季），对 An. comosus 的贡献了 2.4±0.4%（干季）至 4.1±0.3%（湿季），对 Ae. distichantha 的贡献了 3.8±0.4%（干季）至 5±1%（湿季）。相比之下，果蝇并没有为这些凤梨科植物提供营养。处理之间的叶绿素和类胡萝卜素浓度没有差异。接受粪便的植物仅在湿季时具有更高的可溶性蛋白质浓度和叶片生长速率（RGR）。
这些结果表明，蜘蛛和凤梨科植物之间的共生关系具有季节性限制，产生有条件的结果。养分吸收存在种间差异，可能与每个物种的表现和光合作用途径有关。B. balansae 似乎将氮用于生长，而 Ae. distichantha 显然将氮储存起来以应对营养压力。凤梨科植物吸收来自蜘蛛粪便的氮多于来自果蝇的氮，这加强了捕食者在这些消化共生关系中所起的有益作用。
