Robert S. Anderson. 1998. Weevils (Curculionoidea) 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.

WEEVILS (CURCULIONOIDEA)

(excluding Scolytidae, Platopodidae)

Robert S. Anderson

BIODIVERSITY AND ZOOGEOGRAPHY

The 233 species of Curculionoidea found in the Montane Cordillera ecozone represent 80.6% of the Curculionoidea (exclusive of Scolytidae and Platypodidae) known from British Columbia (Bousquet 1991). Montane Cordillera weevils can be assigned to nine generalized geographical distribution patterns (Table 1):

• Widespread: found throughout most of North America. This is the predominat distribution pattern exhibited by the weevils of the Montane Cordillera. A total of 73 species of weevils (31.3%) fit this distribution pattern. Most of these are in a variety of habitats or in wetlands, although a few are in montane transition in association with Salicaceae; some of these species are introduced by humans.
• Northern transcontinental: found or expected to be from coast to coast in Canada extending marginally into any or all of the northern United States. In eastern North America, some species can have disjunct population in Appalachia. A total of 32 species of weevils (13.7%) fit this distribution pattern.
• Western montane: found in the western mountains of Canada and the United States, they may extend south as far as California and even Mexico in the far west and New Mexico and Colorado to the east. A total of 53 species (22.7%) fit this pattern.
• Western montane, northern: found in the western mountains of Canada north into Alaska and the Yukon, but not south into the United States. Only three species of weevils show this distribution pattern, two of which have distributions extending into the Palearctic region.
• Northern transcontinental/western montane: found in both geographic regions noted previously. A total of 25 weevil species (10.7%) show this distribution pattern.
• Western arid: found in arid lands of British Columbia and Alberta extending south into similar habitat in various of the western United States. A total of 25 weevil species (10.7%) show this distribution pattern.
• Western/central arid: found in arid lands of British Columbia extending east into Saskatchewan or even Manitoba and south into similar habitat in various of the western and central United States. A total of 16 weevil species (6.9%) show this distribution pattern.
• BC endemic: found only in the province of British Columbia. Five species of Curculionidae are endemic to British Columbia.
• Holarctic: found naturally in both the Nearctic and Palearctic regions; does not include species introduced by humans. Seventeen species of weevils (7.3%) are Holarctic in distribution.

Montane Cordillera weevils are associated with one of six generalized habitats types (Table 2):

• Montane conifer: In montane forests generally in association with coniferous trees. A total of 34 weevil species (14.6%) are known from this habitat type. Most of these species are associated with species of Pinaceae.
• Montane transition: In montane forests generally in association with non-coniferous plants. Some species can extend to lower elevations into the arid-montane transition zone or into low dry valleys (but generally in riparian situations). A total of 71 weevil species (30.5%) are known from this habitat type. Most of these species are associated with a variety of plant taxa, Salicaceae, Rosaceae, or understory herbaceous species.
• Alpine: At higher elevations above tree line, outside the ecozone perhaps extending north into tundra. Only two species of Apion show this habitat association; both are associated with herbaceous Fabaceae.
• Wetlands: In marshes, swamps or like habitats. A total of 70 weevil species (30.0%) are known from this habitat type. Generally, these species are associated with emergent aquatic macrophytes such as Polygonaceae, Typhaceae or Cyperaceae (and relatives).
• Dry valleys: In lower, arid valley bottoms extending east into prairies. A total of 44 weevil species (18.9%) are known from this habitat type. These species are usually in association with arid land herbaceous plants such as Fabaceae and Cruciferae but some are associated with Artemisia or other Asteraceae.
• Various: In various habitats, including wastelands or roadsides. A total of 18 weevil species are known from a range of habitats. Most of these species are likely in association with herbaceous plants long roadsides or in disturbed situations.

Species in montane conifer or montane transition habitats dominate the fauna with 105 species (45.2% of total).

Notable families of plants serving as hosts for weevils in the Montane Cordillera include Pinaceae, Salicaceae, Fabaceae, Cruciferae and Rosaceae. Some species are pests of the forest industry (e.g., species of Pissodes and Hylobius), some pests of legume crops including clover (e.g., species of Sitona, Hypera and Tychius), some of cultivated crucifers (e.g., species of Ceutorhynchus) and some of cultivated fruits (e.g., species of various Otiorhynchinae, Magdalis, Conotrachelus and Anthonomus). Adults of some species of Otiorhynchinae occasionally are associated with buds of fruits trees and have been noted to cause serious damage on a regional scale (Campbell et al. 1989).

Twenty-four species of weevils (10.3%) in the Montane Cordillera are introduced. These include species in such genera as Sitona, Otiorhynchus, Hypera, Tychius, Gymnetron, Ceutorhynchus, and Rhinoncus. Species associated with Fabaceae, particularly the clovers, and Cruciferae appear to predominate.

Scudder (1994) reported one species of Apionidae, 17 species of Curculionidae, and one species of Scolytidae as potentially rare and endangered within British Columbia. Of these, one species of Apionidae and 10 species of Curculionidae occur within the Montane Cordillera (Table 3). Blades and Maier (1996) suggest the addition of one anthribid (Trigonorhinus annulatus) and one curculionid (Cylindrocopturus helianthus) as candidates for potentially rare and endangered status within British Columbia (Table 3). Herein, 20 additional species are suggested as candidates for potentially rare and endangered status (Table 3). These species have one or a very few records of collection from British Columbia but in the absence of more information at present are best considered vulnerable. All candidates for potentially rare and endangered status are in need of further study before their actual vulnerability can be ascertained with any degree of confidence.

Despite the fact that the 44 species from arid habitats account for only 19% of the fauna of the Montane Cordillera, 22 of the 33 species (66.6%) that are considered potentially rare and endangered are found in this habitat type. Contrastingly, only 9 species considered potentially rare and endangered are found in montane conifer or montane transition habitats.

Five species of Curculionidae are endemic to British Columbia. These are Anthonomus deceptus Sleeper (Copper Mountain), Ceutorhynchus opertus Brown (Oliver), Ceutorhynchus squamulosus Sleeper (Creston), Baris stacesmithi Sleeper (Creston), and Hexarthrum thujae Brown (Revelstoke). While at present condidered endemic, these species need additional study to determine their taxonomic status and actual complete distribution.