Department of Animal Ecology, University of Bayreuth, 95440, Bayreuth, Germany.
NIOO CTO, PO Box 40, 6666 ZG, Heteren, The Netherlands.
Oecologia. 2001 Dec;129(4):577-584. doi: 10.1007/s004420100765. Epub 2001 Aug 9.
Broad bean (Vicia faba), an annual plant bearing extrafloral nectaries (EFN) at the base of the upper leaves, is regularly infested by two aphid species, Aphis fabae and Acyrthosiphon pisum. EFN and A. fabae are commonly attended by the ant, Lasius niger, while Ac. pisum usually remains uninfested. Sugar concentration and sugar composition of extrafloral nectar did not change significantly after aphid infestation. The sugar concentration was significantly higher in EFN (c. 271 µg µl(-1)) than in the honeydew of A. fabae (37.5 µg µl(-1)). The presence of small A. fabae colonies had no significant effect on ant attendance of EFN, which remained at the same level as that on plants without A. fabae. Obviously, there was no significant competitive effect between the two sugar sources. We suggest that the high sugar concentration in the extrafloral nectar may outweigh the higher quality (due to the presence of melezitose) and quantity of aphid honeydew. Ants and the presence of EFN influenced aphid colony growth. While A. fabae colonies generally grew better in the presence of ants, Ac. pisum colonies declined on plants with EFN or A. fabae colonies. We conclude that EFN may provide some degree of protection for V. faba against those sucking herbivores that are not able to attract ants.
蚕豆（Vicia faba）是一种一年生植物，其上部叶片基部有额外的花蜜腺（EFN），经常受到两种蚜虫的侵害，即蚕豆蚜（Aphis fabae）和豌豆蚜（Acyrthosiphon pisum）。额外的花蜜腺和 A. fabae 通常会被黑蚁（Lasius niger）光顾，而 Ac. pisum 通常不会受到侵害。蚜虫侵害后，额外花蜜腺的糖浓度和糖组成没有显著变化。额外花蜜腺的糖浓度明显高于 A. fabae 的蜜露（约 271µgµl(-1)）（37.5µgµl(-1)）。小型 A. fabae 群体的存在对黑蚁对额外花蜜腺的光顾没有显著影响，其光顾水平与没有 A. fabae 的植物相同。显然，两种糖源之间没有明显的竞争效应。我们认为，额外花蜜腺中高浓度的糖可能超过了蚜虫蜜露的更高质量（由于存在蜜二糖）和数量。蚂蚁和额外花蜜腺的存在影响了蚜虫群体的生长。虽然 A. fabae 群体在有蚂蚁的情况下通常生长得更好，但 Ac. pisum 群体在有额外花蜜腺或 A. fabae 群体的植物上则会减少。我们得出结论，额外花蜜腺可能为 V. faba 提供了一定程度的保护，免受那些无法吸引蚂蚁的吸食性害虫的侵害。
