Alniphagus aspericollis

Swaine, 1918

alder bark beetle

Alniphagus aspericollis is a hardwood-killing that colonizes and kills red alder (Alnus rubra) and thinleaf alder (Alnus tenuifolia). Unlike most tree-killing bark beetles that attack conifers, this is one of the few capable of directly killing hardwood . It is in southwestern British Columbia, with principal attacks in May and a second from mid-July to early August. The constructs maternal galleries parallel to the bole in the phloem-cambium, where develop and pupate. It shows loose associations with ophiostomatoid but has a consistent relationship with an undescribed Neonectria species that may function as a symbiote.

Pronunciation

How to pronounce Alniphagus aspericollis: //ælˈnɪfəɡəs æˌspɛrɪˈkoʊlɪs//

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Identification

are small in the ( Scolytinae). Sexes can be distinguished by abdominal tergite structure: females have seventh and eighth abdominal tergites, while males have separate tergites. Gallery architecture resembles that of Ips : single galleries extend approximately 8 cm parallel to the bole length, with mining outward at right angles before turning up or down the trunk. Distinguishable from conifer-attacking bark beetles by its exclusive association with Alnus and coastal Pacific Northwest distribution.

Habitat

Subcortical tissues (phloem-cambium) of alder trees; primarily red alder (Alnus rubra) and thinleaf alder (Alnus tenuifolia). Colonizes both windfalls and standing live trees in forested of the coastal Pacific Northwest.

Distribution

Coastal Pacific North America: British Columbia, Canada (documented from Burnaby Mountain, Greater Vancouver region, Cypress Mountain, Pacific Spirit Regional Park, Tynehead Regional Park, Aldergrove Regional Park, Gates Park, Burnaby Lake Regional Park, and Burnaby Mountain area); northern Idaho, USA; Alaska, USA. Range corresponds with distribution of alder .

Seasonality

in southwestern British Columbia: principal spring attack in May; second attack from mid-July to early August. Mature overwinter in shallow galleries under bark; sporadic occurs during warm winter periods. First galleries observed in early March.

Diet

Phloem-cambium tissues of alder trees. and feed on inner bark; larvae mine through phloem during development.

Host Associations

Alnus rubra - red alder; primary tree, killed by
Alnus tenuifolia - thinleaf alder; documented in northern Idaho
Neonectria sp. nov. - associatepreviously undescribed Neonectria major-like ; isolated from ~67% of , ~59% of phloem , ~94% of infested trees; potentially symbiotic, vectored by beetle
Ophiostoma quercus - associatecasual fungal associate; isolated from ~28% of , ~9% of phloem , ~56% of infested trees
Ophiostoma sp. nov. - associateputatively novel ; infrequently isolated
Cadophora spadicis - associatenew record for red alder; rarely isolated, probably coincidentally carried

Life Cycle

with overlapping . Females initiate attack and construct single galleries ~8 cm long parallel to the bole, laying eggs on both sides. mine outward at right angles to the egg gallery, then turn up or down the bole. occurs in chambers in the inner bark. Maturation from egg to requires 8 weeks. Mature adults overwinter in shallow galleries under bark; larvae, , and callow adults overwinter in galleries.

Behavior

Females attack trees first and are joined by males. Gallery construction and habits similar to Ips . Capable of killing live, apparently healthy or previously stressed alder trees. Unlike conifer-killing , shows only loose association with ophiostomatoid , suggesting limited reliance on fungal for tree-killing.

Ecological Role

Tree-killing causing mortality of early successional nitrogen-fixing hardwoods. Contributes to stand dynamics of red alder forests. May Neonectria sp. nov. , though ecological significance of this relationship remains under investigation.

Similar Taxa

Ips spp.Similar gallery architecture and /larval mining habits; distinguished by preference (conifers vs. alders) and geographic distribution
Conifer-attacking bark beetles (Dendroctonus, Ips, other Scolytinae)Most tree-killing attack conifers; A. aspericollis is distinguished by hardwood specialization and coastal Pacific Northwest distribution
Alniphagus hirsutus in same ; distinguished by specific epithet and potentially different associations or geographic range

More Details

Fungal associations

Unlike conifer-killing with well-documented obligate with ophiostomatoid , A. aspericollis shows only loose associations with this fungal group. The fungal associate is an undescribed Neonectria , which may represent a true symbiotic relationship rather than the ophiostomatoid associations typical of .

Research methods

Gallery construction and have been studied using plexiglass-bark 'sandwiches' that allow direct observation of subcortical activity.