For ant-protected plants, the best defense is a hungry offense
For ant-protected plants, the best defense is a hungry offense
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DOI：
10.1890/08-1580.1
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发表时间：
2009-10-01
期刊：
影响因子：
4.8
通讯作者：
Bronstein, Judith L.
中科院分区：
文献类型：
--
作者：
Ness, J. H.;Morris, W. F.;Bronstein, Judith L.
动物觅食的特点是试图以适当的比例最大限度地摄入碳和氮。超过90个科的植物物种产生丰富的碳水化合物。口花蜜（EFN），一种对蚂蚁和其他杂食性昆虫有吸引力的资源。如果这些节肢动物随后攻击食草动物，这种吸引力可以使植物受益。这种保护性反应是由于人们越来越多地参观和“拥有”提供可预测燃料来源的工厂。在这里，我们提出并测试了一个替代（但不相互排斥）的假设，即获得富含C的碳水化合物增加了蚂蚁对富含N的蛋白质的需求，从而增加了它们攻击宿主植物上的食草昆虫的可能性。如果（1）EFN本身在C和N方面是一种充分平衡的食物来源，（2）蚂蚁的饮食偏好在EFN存在与不存在的情况下相似，（3）蛋白质饥饿的蚂蚁并不更具捕食性，或（4）蚂蚁提供蛋白质比蚂蚁提供碳水化合物对潜在的猎物更具侵略性，则这种“赤字假说”将被拒绝。我们测试这些预测之间的一个公会的沙漠蚂蚁和桶仙人掌Ferocactus wislizeni的保护互利共生。EFN的C：N比超过蚂蚁或潜在猎物的数量级（即，EFN是蚂蚁的N-贫食物）。诱饵研究表明，照料植物的蚂蚁物种在富含N的蛋白质诱饵上招募的工蚁比在富含C的糖诱饵上招募的工蚁更多;当蚂蚁接触到F时，这种差异更加明显。wislizeni EFN.从这些数据中，我们推断蛋白质是一种有价值的资源，当碳水化合物容易获得时，其相对价值会增加。此外，蚂蚁殖民地提供了获得补充碳水化合物更积极地响应代理食草动物比控制殖民地（没有额外的资源提供）或殖民地提供蛋白质。这些结果支持了“赤字”假说的预测，其中植物保护引起的植物介导的膳食不平衡。
Animal foraging has been characterized as an attempt to maximize the intake of carbon and nitrogen at appropriate ratios. Plant species in over 90 families produce carbohydrate-rich extra. oral nectar (EFN), a resource attractive to ants and other omnivorous insects. This attraction can benefit the plant if those arthropods subsequently attack herbivores. This protective response has been attributed to the increased visitation and "ownership" of plants that provide a predictable source of fuel. Here, we propose and test an alternative (but non-mutually exclusive) hypothesis, that access to C-rich carbohydrates increases the ants' desire for N-rich protein and hence the likelihood that they will attack herbivorous insects on the host plant. This "deficit hypothesis" would be rejected if (1) EFN were itself a sufficiently balanced food source in terms of C and N, (2) ant dietary preferences were similar in the presence vs. absence of EFN, (3) protein-hungry ants were not more predaceous, or (4) ants provided access to protein were more aggressive toward potential prey items than were ants provided access to carbohydrates. We test these predictions in a protective mutualism between a guild of desert ants and the barrel cactus Ferocactus wislizeni. C: N ratios of EFN exceeded that of ants or potential prey items by an order of magnitude (i.e., EFN is an N-poor food for ants). Baiting studies demonstrated that plant-tending ant species recruited more workers to N-rich protein baits than to C-rich sugar baits; this difference was more pronounced when the ants had access to F. wislizeni EFN. From these data, we infer that protein is a valuable resource and that its relative value increases when carbohydrates are readily available. Moreover, ant colonies provided access to supplemental carbohydrates responded more aggressively to surrogate herbivores than did control colonies (to which no additional resources were provided) or colonies provided protein. These results support the predictions of the "deficit" hypothesis, wherein plant protection is elicited by plant-mediated dietary imbalances.