Albert T. Finnamore. 1998. Aculeate Wasps in Smith, I.M., and G.G.E. Scudder, eds. Assessment of species diversity in the Montane Cordillera Ecozone. Burlington: Ecological Monitoring and Assessment Network, 1998.

ACULEATE WASPS

(Excluding Formicidae)

Albert T. Finnamore

RESULTS

The Montane Cordillera Ecozone lies for the most part in central and southern British Columbia, excluding the coastal regions. A small portion spans the continental divide which defines the mountain border between British Columbia and Alberta to include a narrow strip approximating the National Park system in Alberta and several small adjacent areas. Species richness of aculeate wasps in the Montane Cordillera Ecozone is presented in Table 1 along with comparative figures for British Columbia and Canada. There are 902 species of Aculeate wasps presently known from Canada, about 45% of the Canadian fauna is found in British Columbia (408 species) of which the Montane Cordillera Ecozone component is 243 species in British Columbia plus an additional 22 species confined to the Alberta section of the Ecozone (Table 2). In groups like Dryinidae, Pompilidae, and Sphecidae, where accurate detailed information is available for the Montane Cordillera Ecozone fauna, about 90% of the British Columbia fauna occurs in the Montane Cordillera Ecozone. The expected aculeate wasp fauna for the Ecozone is estimated at more than 370 species. I estimate about 70% of aculeate wasps have been documented for the Ecozone in this report.

Figures presented in Table 2 indicate that 90% of species (243) occurring in the Ecozone are found on the British Columbia side of the continental divide, which contains the least amount of protected lands. The Montane Cordillera in Alberta is virtually !00% protected but contains only 30% of the fauna known from the Ecozone.

Table 1. Species Richness comparison of Canada, British Columbia, and the Montane Cordillera Ecozone spanning British Columbia and Alberta.

Table 2. Species Richness across the Continental divide in the Montane Cordillera Ecozone.

The aculeate wasps of the Montane Cordillera Ecozone can also be viewed in terms of components based on the distribution of the individual species. Four faunal components were identified in the aculeate wasp species collected in the Ecozone. These are presented in Table 3. The Transcontinental- northern component includes Holarctic species (circumpolar in distribution), with generally northern ranges in North America that dip southward in the mountains It also includes transcontinental species generally distributed from Alaska to Newfoundland. Transcontinental-northern species range from coast to coast in the ecozones spanned by the boreal forest and also dip southward in the mountains. The Transcontinental-southern component species range from coast to coast south of the boreal forest. Collections of these species in the Montane Cordillera, in many cases, represent the northern limits known for many of these species. Eastern species range from the Atlantic Coast westward to the mountains. In many cases the Montane Cordillera collections represent the western limits of the range of eastern species. Western species range west of the 100th meridian to the Pacific Coast and include many grassland endemic species.

Table 3. Aculeate wasp faunal components of the Montane Cordillera Ecozone.

The faunal components identified in Table 3 reflect the diversity of habitats found in the Ecozone. The Transcontinental-northern components (30% of species) tending to occupy wetter, colder, higher altitude habitats dominated by coniferous forest and deciduous shrubs. These conditions occur over most of the Ecozone. The Transcontinental-southern (25% of species) and western components (40% of species) tending to occupy warmer, xeric habitats at lower altitudes dominated by grasslands, or by graminoid vegetation with decidous shrubs (riparian zones). In other words, most species, 65%, of aculeate wasps found in the Montane Cordillera Ecozone prefer the xeric, warm habitats found on lower south-facing slopes or in grasslands. These conditions occur in a small fraction of the Ecozone, the greatest portion of which occurs in the Okanagan Valley.

The number of species in the Montane Cordillera Ecozone that reach the northern limit of their known ranges in the Ecozone is presented in Table 4. An astonishing 169 species (64% of Ecozone fauna) reach northern range limits within the Montane Cordillera Ecozone. Many of these species are Transcontinental-southern in distribution and occur across southern British Columbia or Alberta. A large number are also Western; many of these species reach northern range limits in the Okanagan Valley, and are often restricted to that Valley in the Ecozone. Records of 103 species (about 40%) of aculeate wasps are known from the Okanagan Valley. Of those, there are 69 species, about 25% of the Ecozone aculeate fauna, that do not occur elsewhere in the Ecozone or in British Columbia and are at the northern limits of their ranges.

The Okanagan Valley has been a major fruit crop production area in British Columbia for most of this century. In the last decade there has been a major switch in crops from tree fruits to grapes in support of a burgeoning wine industry. Grape production is a far more intensive agriculture management regime than that associated with tree fruits, and one which entails utilization of every bit of available land, including fence lines and hedgerows.

Table 4. Species potentially subject to extirpation in the Montane Cordillera Ecozone

In addition, the Okanagan Valley is virtually without protected areas. This combination of factors (limited habitat, intensive agriculture, little protected land) mean that Montane cordillera species restricted to the Okanagan Valley are subject to extirpation. Furthermore, the specimens used to compile this assessment were collected, for the most part, before 1970, effectively providing a snapshot of the fauna as it existed at the middle of the century, which may or may not be an accurate reflection of the fauna today.