Distribution, habitats, and redescription of the rare mite species Iphidonopsis sculptus Gwiazdowicz, 2004 (Mesostigmata: Ascidae)

Iphidonopsis sculptus Gwiazdowicz, 2004, is currently known only from the type locality in eastern Poland and a record in southwestern Finland (Huhta, 2016). Here, we record this species from twelve localities elsewhere (Europe, Siberia, Far East of Russia, Canada) indicating its broadly Holarctic geographical range. Another genus member, Iphidonopsis magnanalis (Ma & Yin, 1999), is known only from China. About half of Iphidonopsis sculptus records are associated with litter of coniferous or mixed forests, but the others, including samples with juveniles (deutonymphs), were found in bracket fungi or under tree bark. The finding of two adult females on a bark beetle, Dryocoetes affaber (Mannerheim) (Coleoptera: Curculionidae: Scolytinae), suggests a phoretic association, though members of the closely related genus Zerconopsis Hull, 1918 as well as of all of the subfamily Arctoseiinae are known only from phoretic dispersal by nematoceran dipterans. The morphology of adults and an immature instar (deutonymph) of I. sculptus is redescribed and newly described, respectively, and illustrated in detail. A subdivision of the subfamily Arctoseiinae Evans, 1963 into three tribes is proposed—Arctoseiini Evans, 1963 (including Arctoseius Thor, 1930 and Iphidozercon Berlese, 1903), Zerconopsini tribe n. (Zerconopsis Hull, 1918; Xenoseius Lindquist & Evans, 1965; and Iphidonopsis Gwiazdowicz, 2004), and Maxiniini tribe n. (Maxinia Lindquist & Makarova, 2012).

Xylophagous insect species composition and patterns of substratum use on fire-killed black spruce in central Quebec

Several xylophagous insect species have adapted to recurrent fires in boreal forests and use high-quality habitats created by these disturbances. To characterize the xylophagous insect assemblages of fire-killed black spruce and their patterns of substratum use, eighty-four 40 cm long bole segments were cut in 2000 and 2001 according to tree diameter, segment height, and fire severity criteria in a 1999 burn in the Grands-Jardins provincial park, Quebec, Canada. The segments were suspended in rearing cages, and neonates were collected until November 2001. The cerambycid Mono chamus scutellatus (Say) and the scolytids Dryocoetes affaber (Mann.) and Polygraphus rufipennis (Kirby) were the most common beetles collected. For all common taxa, more neonates emerged from larger-diameter trees. Few neonates emerged from the upper parts of the trees, and none of the species were specialist of the upper parts of the tree. Fire severity had a drastic effect, and heavily charred trees yielded very few insects. The effect of fire severity on insect colonization density varies widely among tree species. This effect may be linked to varying bark thickness and to bark's insulating potential against water loss during the fire. The host's vigor before its death, measured from growth rings of the last 10 years, had a positive effect on cerambycid emergence, but no effect on scolytids.

Bark beetles and fungal associates colonizing white spruce in the Great Lakes region

We examined the major bark beetles and associated fungi colonizing subcortical tissues of white spruce (Picea glauca (Moench) Voss) in the Great Lakes region. Trees were felled at one northwestern Wisconsin site in a preliminary study in 1997 and at 10 sites throughout northern Wisconsin, Minnesota, and Michigan in 1998. Fungal isolations were made from beetles colonizing felled trees, beetles that emerged from felled trees, tissue of colonized trees, and tissue of uncolonized trees. Dryocoetes affaber (Mannerheim) and Polygraphus rufipennis (Kirby) accounted for over 90% of the insects that emerged from logs. Time of colonization had a significant effect on abundance and composition of emerging insects. New records include Dendroctonus rufipennis (Kirby) in Wisconsin and two Michigan counties and Crypturgus borealis (Swaine) in Wisconsin and Minnesota and one Michigan county. Five fungal species from two genera were isolated both from beetles and colonized tree tissue. None were isolated from uncolonized trees. Ten new beetle–fungal associations were identified. The association of specific fungi with specific bark beetles, both as they colonize and emerge from hosts and the isolation of these fungi from subcortical tissues of colonized but not uncolonized trees, is consistent with vector relationships. We compare our results with bark beetle – fungal associations reported elsewhere in spruce and suggest possible mechanisms constraining population growth by Dendroctonus rufipennis in the Great Lakes region.

SCOLYTIDAE ASSOCIATED WITH FELLED WHITE SPRUCE IN ALASKA

Pheromone baited traps and trap trees attracted an aggregate of 29 scolytid species associated with white spruce in three localities in Alaska. Species diversity was higher in the Fairbanks (lat. 64°45′) area than in the Brooks Range (lat. 68°15′) or Kenai Peninsula (lat. 60°37′). Scolytids were found inhabiting all bark-producing areas of the tree from the roots to small branches with the highest density in the tree bole. The most abundant scolytids were Ips perturbatus (Eichhoff), Ips tridens tridens (Mannerheim), Polygraphus rufipennis (Kirby), Dryocoetes affaber (Mannerheim), Trypodendron lineatum (Olivier), and Scolytus piceae (Swaine).

CHARACTERISTICS OF SPRUCE BEETLE (COLEOPTERA) INFESTATION IN FELLED WHITE SPRUCE IN ALASKA

The antiaggregation pheroraone MCH was ineffective in preventing spruce beetle infestation in felled spruce near Hope, Alaska. In October, most progeny were larvae but some were pupae and new adults. Densities of spruce beetle attacks and progeny on the shaded under side of stems were about twice those on the upper side, whereas attacks of Polygraphus rufipennis (Kirby) and Dryocoetes affaber (Mann.) on the upper side were 100 times those on the under side. Ips tridens engelmanni Swain was present in only 2% of bark samples. Entomophagous insects were scarce; only Medetera sp. and Coeloides sp. were found. Spruce beetle progeny were 45 times more abundant than attacking parents. Factors affecting the efficiency of sampling spruce beetle attacks and progeny are discussed.

SCOLYTID FLIGHT IN WHITE SPRUCE STANDS IN ALASKA

Within white spruce stands near Fairbanks, Alaska, and on the Kenai Peninsula, Alaska, Dendroctonus rufipennis, Ips spp., and Trypodendron lineatum disperse in late May and early June; other scolytids fly during June and July. Flight in interior Alaska precedes by about 2 weeks that on the Kenai Peninsula. Mean daily temperatures during spring and early summer are generally warmer in the interior than in coastal areas. There was a large increase in the total number of beetles in a thinned area, mostly of Dryocoetes affaber.

OCCURRENCE OF MYCANGIA IN THE BARK BEETLE DRYOCOETES CONFUSUS (COLEOPTERA: SCOLYTIDAE)

Paired mandibular mycangia are present in both sexes of the bark beetle Dryocoetes confusus Sw. These fungus repositories were not found in either sex of another bark beetle of the same genus, Dryocoetes affaber Mann.