K.G.A. Hamilton. 1998. "Short-Horned" Bugs (Homoptera: Auchenorrhyncha) 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.

"SHORT-HORNED" BUGS
(HOMOPTERA: AUCHENORRHYNCHA)

K.G.A. Hamilton
Eastern Cereal and Oilseed Research Centre
Agriculture & Agri-Food Canada
Ottawa, Ontario
K1A 0C6

ABSTRACT

The Montane Cordillera Ecozone (MCE) fauna of “short-horned” bugs is species-rich but very different from that found in the Mixwood Plains Ecozone of eastern Canada. Together, these two ecozones have 80% of the Canadian bug fauna. A total of 484 species of Homoptera- Auchenorrhyncha are reported from the MCE. Of these, 129 are not geographically analysed, as they represent 25 imported (mainly European) species plus 104 wind-transported microleafhoppers. Of the remainder, 50% are confined to valleys; 6% are confined to mountains; and the rest are widespread species of the boreal and hemiboreal zones. Endemism is most pronounced in southern valley systems. Of the southern ecodistricts, only #992 lacks any record of endemic species. The valley-restricted species are mostly in the Okanagan (65% of the valley fauna), divided roughly equally between ecodistricts 1007 and 1010, each with only about 50% of these species in common. Ecodistrict 1007 has the majority of introduced leafhoppers in the MCE due to the intensity of agriculture there. Districts 982, 1005-6 and 1015 are also species- rich faunas, with 39-44 valley-restricted species. Districts 991, 1002, 1009 and 1011 are less rich, with 22-29 such species; and minor endemic faunas (10 or fewer species) are found in districts 972, 979, 984, 990, 997-8, 1001, 1003-4, 1008, 1012-3, 1016, 1018 although these faunas are usually confined to just a small part (often a single short valley) within each ecodistrict. The strongest distinctions between the valley faunas are between the north and south across 51·N latitude, which represent faunas of different ages. Northern districts (972, 978-9, 982) probably represent Hypsithermal relicts from the Great Plains via the Peace River valley of Alberta, while southern districts are still being enriched by annual invasions from southern grasslands. These valley faunas of modern origin show lesser distinctions between valleys east and west of 118·W longitude. These faunas probably came from the Great Plains of Montana, and the Great Basin of Washington state respectively. Ecodistrict 1002 is unique in the MCE as its endemic fauna probably came from the coastal intermontane valleys of Oregon and Washington states during a postglacial period when that area was drier than at present.

The presence of great topographical differences in close association makes the MCE fauna resilient in the face of climate change but the fragmented nature of the faunal associations makes them highly vulnerable to human activities. The fauna of the Okanagan valley is particularly at risk, being both speciose, competing unsuccessfully with many imported species, and under strong pressures from human land use.

 

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