Stubblefield J W, Seger J, Wenzel J W, Heisler M M
Cambridge Energy Research Associates, Massachusetts 02138.
Philos Trans R Soc Lond B Biol Sci. 1993 Mar 29;339(1290):397-423. doi: 10.1098/rstb.1993.0039.
More than 3000 prey representing 108 species of bees and wasps were identified from exoskeletal remains taken from nests of the beewolf Philanthus sanbornii at a site in eastern Massachusetts over a period of five years. Quantitative reference samples totalling more than 4000 items were collected from flowers at the same site over a period of four years. These data give a uniquely detailed view of the way in which a generalist predator exploits a diverse prey community. Most species show striking year-to-year variation in relative abundance, in both the prey and reference collections, but the overall abundances of species tend to be similar in the two collections, as do their sex ratios. This shows: (i) that P. sanbornii takes virtually every bee and wasp species found at flowers during its flight season (except for the relatively small number of species too large to handle); (ii) that prey are taken at rates roughly proportional to their local abundances (with a few exceptions); and (iii) that the local bee and wasp communities have lively dynamics (at least on spatial scales equivalent to the flight ranges of P. sanbornii females). Prey species are non-randomly distributed among nests of individual females within years, and among cells within nests, in a pattern suggesting that females often return repeatedly to hunting sites at which they have had success; the pattern does not suggest that individual females develop preferences for particular prey taxa. The size-abundance distributions of female bees appear to be trimodal at both the individual and species levels, most strongly so when cleptoparasitic species are removed from the sample. Such patterns are seen weakly or not at all in the size-abundance distributions of male bees, male wasps, and female wasps. Bees and wasps of both sexes visit flowers for nectar, but only non-parasitic female bees harvest pollen; this suggests that the multimodality may be caused by aspects of pollen collection that tend to scale with size. The seven Philanthus species of eastern North America vary greatly in size, but they share a common set of relatively small prey species. As in other parts of North America, larger species of Philanthus tend to have relatively broad diets because they also take larger prey that are not available to their smaller congeners. However, long-tongued bees appear to be under-represented in the diets of most North American Philanthus outside the zebratus species group.
在五年时间里，从马萨诸塞州东部一个地点的桑氏狼蜂巢穴的外骨骼残骸中，识别出了代表108种蜜蜂和黄蜂的3000多只猎物。在四年时间里，从同一地点的花朵上收集了总计4000多个项目的定量参考样本。这些数据提供了一个独特而详细的视角，展示了一种泛化捕食者利用多样化猎物群落的方式。在猎物和参考样本收集中，大多数物种的相对丰度都呈现出显著的逐年变化，但两个收集中物种的总体丰度及其性别比例往往相似。这表明：（i）桑氏狼蜂在其飞行季节几乎捕食在花朵上发现的每一种蜜蜂和黄蜂物种（除了相对少数太大而无法处理的物种）；（ii）猎物的捕食率大致与其当地丰度成比例（有一些例外）；（iii）当地的蜜蜂和黄蜂群落具有活跃的动态（至少在与桑氏狼蜂雌性飞行范围相当的空间尺度上）。猎物物种在年内单个雌性的巢穴之间以及巢穴内的巢室之间呈非随机分布，这种模式表明雌性常常会反复回到它们成功捕食过的狩猎地点；这种模式并不表明单个雌性对特定的猎物分类群有偏好。雌性蜜蜂的大小 - 丰度分布在个体和物种水平上似乎都是三峰的，当从样本中去除盗寄生物种时最为明显。在雄性蜜蜂、雄性黄蜂和雌性黄蜂的大小 - 丰度分布中，这种模式要么很弱，要么根本看不到。两性的蜜蜂和黄蜂都会访问花朵获取花蜜，但只有非寄生性的雌性蜜蜂采集花粉；这表明多峰性可能是由与大小相关的花粉采集方面的因素引起的。北美东部的七种狼蜂在大小上差异很大，但它们共享一组相对较小的猎物物种。与北美其他地区一样，较大的狼蜂物种往往有相对广泛的食谱，因为它们还捕食较小的同类无法捕食的较大猎物。然而，在斑马狼蜂物种组之外的大多数北美狼蜂的食谱中，长舌蜜蜂似乎占比不足。
