BIOLOGY Diversity and Host Use of (: , ) Phoretic on Bark (Coleoptera: Scolytinae): Global Generalists, Local Specialists?

1,2,3 1 2 WAYNE KNEE, MARK R. FORBES, AND FRE´ DE´ RIC BEAULIEU

Ann. Entomol. Soc. Am. 106(3): 339Ð350 (2013); DOI: http://dx.doi.org/10.1603/AN12092 ABSTRACT Mites (Arachnida: Acari) are one of the most diverse groups of organisms associated with bark beetles (: Scolytinae), but their and ecology are poorly understood, including in Canada. Here we address this by describing the diversity, composition, and host associations of mesostigmatic and oribatid mites collected from scolytines across four sites in eastern Ontario, Canada, in 2008 and 2009. Using Lindgren funnel traps baited with ␣-pinene, ethanol lures, or Ips pini (Say) pheromone lures, a total of 5,635 bark beetles (30 species) were collected, and 16.4% of these beetles had at least one . From these beetles, a total of 2,424 mites representing 33 species from seven families were collected. The majority of mite species had a narrow host range from one (33.3%) or two (36.4%) host species, and fewer species had a host range of three or more hosts (30.3%). This study represents the Þrst broad investigation of the acarofauna of scolytines in Canada, and we expand upon the known (worldwide) host records of described mite species by 19%, and uncover 12 new species. Half (7) of the 14 most common mites collected in this study showed a marked preference for a single host species, which contradicts the hypothesis that nonparasitic mites are typically not host speciÞc, at least locally. Moreover, host records from the literature and those of this study together suggest that at a global scale, bark mites have a broad host range, while at a local scale many species are host speciÞc.

KEY WORDS host speciÞcity, species composition, Mesostigmata, Oribatida,

The subcortical niche of dead, dying, and living trees cies and subspecies in Canada and the continental provide a habitat for a broad assemblage of - United States (Rabaglia 2002). burrowing beetles (Cerambycidae, Buprestidae, Cur- Mites represent the largest group of as- culionidae: Scolytinae) and a suite of organisms that sociated with bark beetles, and their association is exploit these beetles or their galleries. This symbiotic ancient and diverse. One of the oldest records of mites community is dominated by mites, nematodes, and associated with are tortoise mites (Mesostig- fungi. True bark beetles, Scolytinae, feed and repro- mata: Uropodina) attached to bark beetles in 20Ð40 duce in the cambium or xylem tissue of many tree million year old amber (Poinar 1982). In total, 97 species across the globe (Wood 1982). Many scolytine species of mites from 65 genera and 40 families were species feed on dead or dying trees, and these species collected under the bark and from the galleries of bark likely serve a beneÞcial role in forest ecosystems as beetle infested trees (Moser and Roton 1971); nutrient recyclers. However, some species of the gen- however, some of the mites collected by Moser and era Ips, , and Scolytus cause extensive Roton (1971) may be primarily dead wood or bark economic losses in North America (Wood 1982). For inhabitants and not truly associated with bark beetles. example, Dendroctonus rufipennis (Kirby) kills Ϸ0.55 Some scolytine species of temperate forests are asso- billion board feet of timber per year, and Den- ciated with an assemblage of 15Ð20 mite species droctonus ponderosae Hopkins, is responsible for an (Lindquist 1969); however, the acarofauna of most estimated timber loss of 1.5 billion board feet per year bark beetle species are poorly understood taxonomi- (Wood 1982). Over 5,800 described species of scoly- cally and ecologically. tines are known worldwide, and there are Ϸ525 spe- Mites dwelling in bark beetle galleries are generally phoretic, in that they hitch a ride on dispersing beetles to new coarse woody debris. These mites include 1 Carleton University, 1125 Colonel By Drive, Department of Bi- fungivores, predators of insects and nematodes, om- ology, 209 Nesbitt Bldg., Ottawa, ON, Canada, K1S 5B6. nivores, and parasites and parasitoids of scolytines 2 Canadian National Collection of Insects, and Nema- (Lindquist 1970). The symbiotic relationship between todes, Agriculture and Agri-Food Canada, 960 Carling Ave., K.W. Neatby Bldg., Ottawa, ON, Canada, K1A 0C6. mites and their hosts may vary from beneÞcial to 3 Corresponding author, e-mail: [email protected]. detrimental across and even within mite species

0013-8746/13/0339Ð0350$04.00/0 ᭧ 2013 Entomological Society of America 340 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 106, no. 3

(Hirschmann and Ru¨ hm 1955; Kinn 1967, 1980, 1984; ␣-pinene and 95% ethanol (released at 2 g/d and 400 Moser 1975). Overall, the nature of symbiosis and the mg/d, respectively) lures (Synergy Semiochemicals) impact that most mite species have on their bark bee- to attract beetles seeking dead or dying coarse woody tle hosts are largely unknown. Generally, predatory debris. At mid-May, trap lures were changed so that in and omnivorous (nonparasitic) mite species are not each site there were four traps baited with ␣-pinene considered to be host-speciÞc, but rather they tend to and 95% ethanol lures, and one trap baited with ips- be habitat-speciÞc, and are reported from a broad dienol and lanerione lures, for the remainder of the range of coexistent host taxa that share similar habitats 2008 sampling period. Traps were emptied approxi- (Lindquist 1970, Moser 1995). Indeed, many bark bee- mately every 2 wk, trap lures were replaced every 8 tle mites are found on a broad range of hosts (Moser wk, insecticide strips were replaced during each visit and Roton 1971), which suggests that these mites are to maintain effectiveness, and any mites detached not speciÞc. However, since most surveys provide from their host were discarded with the preservative. little data beyond the observed host association, it is The diversity and abundance of mites may have been unclear how strong the actual relationship is between underestimated by ignoring the detached mites; how- these mites and their hosts. ever, without knowledge of the host association the The mites associated with several species of scoly- loose mites would provide misleading data. Each bee- tines have been surveyed in other countries, but usu- tle specimen captured was placed individually into a ally these surveys focus on economically important 1.5 ml microfuge tube with 95% ethanol. species, such as Ips typographus (L.) in Germany and From mid-April to early August 2009, sampling was Sweden (Moser and Bogenschutz 1984, Moser et al. repeated in Algonquin PP (N1, N2) because of the 1989), Dendroctonus frontalis Zimmermann, in Loui- high abundance and diversity of bark beetles obtained siana, Central America, and Mexico (Moser and Roton in these sites in 2008, and sampling was also conducted 1971, Moser et al. 1974), D. ponderosae in Alberta in two new sites in deciduous stands to broaden the (Canada; Mori et al. 2011), Scolytus multistriatus (Mar- diversity of scolytines and mites collected: one near sham) and Scolytus pygmaeus (F.) in Austria (Moser Carbine road (S3) outside of Pakenham (45.330, et al. 2005). In this study we attempted to address the Ϫ76.371), and another on Highway 132 (S4) near scarcity of data in Canada, by describing the diversity, Dacre (45.369, Ϫ76.988). Sites S3 and S4 were in mixed prevalence, and host range of two major groups of wood forest dominated by deciduous trees. Four Lind- mites (Mesostigmata, Oribatida) associated with bark gren traps with propylene glycol insecticide were beetles collected across six sites in eastern Ontario, placed in each study site following the same protocol. using baited Lindgren funnel traps. In addition, using Traps were baited with ␣-pinene (␣-pinene is an at- our Þndings on host range of bark beetle mites, as well tractant for conifer-feeding scolytines) and 95% eth- as published host records, we explored the hypothesis anol lures in sites N1 and N2, and baited with 95% that nonparasitic mites can be host speciÞc, at least at ethanol lures in sites S3 and S4. Traps were visited and a local scale. specimens were collected following the same protocol as in 2008. Identifications and Mite Associations. Scolytines Materials and Methods were identiÞed to species using a dissecting micro- Study Sites and Sampling Design. Bark beetles were scope and keys from Bright (1976) and Wood (1982), sampled in four study sites in eastern Ontario from and tribes were based on AlonsoÐZarazaga and Lyal mid-April to late August in 2008. Two sites were in the (2009). The presence, abundance, and attachment mixed wood ecozone, one near Charleston Lake (S1) location of mesostigmatic and oribatid mites (hereaf- (44.500, Ϫ76.072) and the other near Frontenac Pro- ter mites) was recorded; other mites (, vincial Park (PP) (S2) (44.447, Ϫ76.577). The other Astigmata) were not retained or studied. Mesostig- two sites were in the boreal shield ecozone, in Algon- matic and oribatid mites were selected because they quin PP: Algonquin site 1 (N1) (45.902, Ϫ77.605) and are abundant and conspicuous mites that Þrmly attach Algonquin site 2 (N2) (45.895, Ϫ78.071). Sites S1 and to their host. Prevalence was deÞned as the percent- S2 were in isolated stands of white pine, along the age of beetles with mites of a given species. Intensity Frontenac axis, surrounded by deciduous forests. Sites was deÞned as the number of mites of a given species, N1 and N2 were in large contiguous stands of white carried per beetle with mites (beetles without mites and red . In each site, Þve Lindgren 12-unit excluded). All mesostigmatic and oribatid mites were funnel dry traps (Synergy Semiochemicals Corp., removed from the host, cleared in 85% lactic acid for Burnaby, British Columbia) with four 1 cm3 pest strips 1Ð24 h depending on the degree of opacity, slide- (Ortho Home Defense Max; to kill beetles and mites) mounted in a polyvinyl alcohol medium and cured on and baited with lures, were placed at least 16 m apart; a slide warmer at Ϸ40ЊC for 3Ð4 d. Slide-mounted collection cups were Ϸ80 cm off the ground and at specimens were examined using a compound micro- least 2 m from any host trees (distance from trees, trap scope (Leica DM 5500B or Nikon 80I) and identiÞed height, and distance between traps based upon Miller to species or morphospecies using taxonomically in- and Duerr 2008). From mid-April to mid-May, three formative morphological characters based on species traps were baited with ipsdienol (100 mg released at descriptions from the literature (Hirschmann 1960, Ϸ400 ␮g/d) and lanerione (4 mg) to attract I. pini 1972, 1989; Hirschmann and ZirngieblÐNicol 1961; adults, and the other two traps were baited with Hurlbutt 1967; Hirschmann and WiÏniewski 1982, May 2013 KNEE ET AL.: HOST USE OF MITES PHORETIC ON BARK BEETLES 341

Table 1. Total abundance of scolytine species collected across four sites in eastern Ontario in 2008 and 2009 (° mites present)

2008 sitesa 2009 sitesa Tribe Beetle species N1 N2 S1 S2 N1 N2 S3 S4 Corthylini Corthylus punctatissimusb ÑÑ 1 1ÑÑÑ1 Gnathotrichus materiarius 135Њ 26 8Њ 14Њ 19Њ 39Њ ÑÑ G. materiariusc 2 2ÑÑÑÑÑÑ Monarthrum malib ÑÑÑÑÑ 1ÑÑ Pityophthorus sp.15282235Ñ3 Pityophthorus sp.c Ñ 4 3 3ÑÑÑÑ Crypturgini Crypturgus pusillus 2ÑÑÑÑÑÑÑ Dryocoetini affaber 9ÑÑ75Њ 1Ñ Ñ D. affaberc 1ÑÑÑÑÑÑÑ D. autographus 22Њ ÑÑÑ11Њ Ñ1Ñ Lymantor decipiensb ÑÑÑÑÑ 1ÑÑ L. decipiensb,c ÑÑ 140ÑÑÑÑ Hylastini opacus 154Њ 221Њ 10 11 17 388 Ñ Ñ H. opacusc 1 3 4ÑÑÑÑÑ H. porculus 603Њ 42Њ 14Њ 67 291Њ 104Њ 21 H. porculusc Ñ 1ÑÑÑÑÑÑ pinifex 26Њ 11Њ 113Њ 6Њ ÑÑ H. pinifexc 1ÑÑÑÑÑÑÑ aculeatusb ÑÑ 1ÑÑÑ 315Њ H. aculeatusb,c ÑÑ 1Њ ÑÑÑÑÑ Hylurgini Dendroctonus rufipennis 2ÑÑÑÑÑÑÑ D. valens 102Њ 93Њ 1312Њ 194Њ ÑÑ D. valensc Ñ 2 1ÑÑÑÑÑ Hylurgopinus rufipesb ÑÑÑÑÑÑÑ4 piniperda ÑÑÑÑÑ 1ÑÑ Ipini Ips grandicollis 80Њ 93Њ 16Њ 23 30Њ 83Њ ÑÑ I. grandicollisc Ñ 2ÑÑÑÑÑÑ I. perrotic Ñ 1ÑÑÑÑÑÑ I. pini 9Њ 5Њ Ñ62Њ 7Њ ÑÑ I. pinic 170Њ 504Њ 511Њ 230Њ ÑÑÑÑ Orthotomicus caelatus 142Њ 36Њ 12Њ 10Њ 15Њ 83Њ ÑÑ O. caelatusc 1ÑÑÑÑÑÑÑ hopkinsi 6251Ñ114Њ Ñ3 P. hopkinsic 4142 1ÑÑÑÑ P. plagiatus Ñ6ÑÑ11ÑÑ P. plagiatusc 1 6ÑÑÑÑÑÑ Pityogenes sp. Ñ 1ÑÑÑÑÑÑ Pityokteines sparsus 1 3 1ÑÑ 1Њ Ñ2Њ P. sparsusc Ñ 3ÑÑÑÑÑÑ Polygraphini rufipennis 18 8Њ Ñ111Њ 1Њ 2Њ 1 P. rufipennisc Ñ 1ÑÑÑÑÑÑ Xyleborini Xyleborus disparb ÑÑÑÑÑÑ1460 X. sayib 3Њ 21924ÑÑ3931 Xyloterini Trypodendron lineatum 232Њ Ñ2Ñ214Ñ6 T. lineatumc 9Ñ 1ÑÑÑÑÑ T. retusumb ÑÑÑÑ 2Њ 2Ñ Ñ Xyloterinus politusb 1ÑÑÑ2366 X. politusb,c 7Ñ90Њ 1ÑÑÑÑ Total no. individuals 1,562 600 89 170 446 939 67 133 no. individualsc 197 543 614 275 Ñ Ñ Ñ Ñ Total no. species 19 15 14 13 17 20 7 12 no. speciesc 10 12 9 5 Ñ Ñ Ñ Ñ

a N1, Algonquin park 1; N2, Algonquin park 2; S1, Charleston lake; S2, Frontenac; S3, Packenham; S4, Dacre. b Scolytine species associated with deciduous host species, all other species are associated with coniferous hosts (Wood 1982). c Traps baited with Ips pini pheromone lures.

1986, 1987, 1989; Wunderle et al. 1990). Voucher spec- 1). Beetle abundance was higher in 2008 than in 2009 imens are deposited in the Canadian National Collec- (2,421 and 1,585 beetles, respectively), but species tion of Insects, Arachnids and Nematodes, in Ottawa, richness was higher in 2009 than in 2008 (26 and 23 Canada. species, respectively), possibly because two distinct forest types were sampled in 2009 (Table 1). Beetles were collected almost exclusively in the spring; in Results 2008, 96% of all beetles were collected from mid-April Traps with General Lures. In total, 4,006 bark bee- to mid-June, and in 2009, 98% from mid-April to late tles from 29 species, 21 genera and 10 tribes were June. Hylastes porculus Erichson (25Ð30% of all beetle collected in traps with general lures (␣-pinene, eth- individuals), H. opacus Erichson (16Ð26%), and Den- anol, or both), across four sites in 2008 and 2009 (Table droctonus valens LeConte (8Ð13%) were the three 342 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 106, no. 3

Table 2. Prevalence (%) (total abundance) of mites associated with scolytines collected across four sites in eastern Ontario in 2008 and 2009

Mite Gnathotrichus Dryocoetes D. Hylastes H. Hylurgops Hylesinus Hylesinus Dendroctonus Ips familya Mite species materiarius affaber autographus opacus porculus pinifex aculeatusb aculeatusb,c valens grandicollis

AMR Epicriopsis n.sp. 0.4(1) ÑÑÑ0.1 (1) 2.1 (1) Ñ Ñ 1 (4) 0.3 (1) DGM 0.4 (1) Ñ Ñ 0.4 (3) 0.5 (6) 8.3 (7) Ñ Ñ 4.9 (26) 3.1 (11) hexaspinosus D. louisianae ÑÑÑÑÑÑÑÑÑ0.9 (3) D. n.sp. 1 Ñ Ñ Ñ 0.1 (1) 0.1 (1) Ñ Ñ Ñ 18.3 (156) Ñ D. n.sp. 2 Ñ Ñ Ñ Ñ 0.4 (8) 22.9 (20) Ñ Ñ Ñ Ñ D. n.sp. 3 Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ D. n.sp. 4 Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 0.2 (1) Ñ D. neodisetus ÑÑÑÑÑÑÑÑ0.2 (1) Ñ D. quadrisetosimilis ÑÑÑÑÑÑÑÑÑÑ D. quadrisetus ÑÑÑÑÑÑÑÑÑ1.2 (4) D. quadritorus ÑÑÑ0.1 (1) 0.3 (3) Ñ Ñ Ñ 1.2 (5) 0.3 (1) Longoseius ÑÑÑÑ0.1 (1) Ñ Ñ Ñ Ñ Ñ cuniculus MAC Macrocheles n.sp. Ñ Ñ Ñ Ñ 0.3 (3) Ñ Ñ Ñ 0.5 (2) Ñ MLC Proctolaelaps fiseri ÑÑÑÑ1.4 (20) Ñ Ñ Ñ Ñ Ñ P. hystrix ÑÑÑ0.1 (1) Ñ Ñ Ñ Ñ 1 (5) Ñ P. n.sp. 1 Ñ Ñ Ñ Ñ 0.2 (6) Ñ Ñ Ñ 0.2 (1) Ñ P. n.sp. 2 Ñ Ñ Ñ Ñ 2.3 (60) Ñ Ñ Ñ Ñ Ñ P. n.sp. 4 Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ TRM Trichouropoda ÑÑÑÑÑÑÑÑ0.2 (1) 1.5 (7) australis T. bipilis ÑÑÑÑÑÑ10.5 (3) 100 (1) Ñ Ñ T. fallax ÑÑÑÑÑ6.3 (4) Ñ Ñ Ñ Ñ T. hirsuta ÑÑÑÑ0.4 (10) 2.1 (3) Ñ Ñ 2 (10) 0.9 (4) T. lamellosa ÑÑÑÑ0.2 (2) Ñ Ñ Ñ 0.7 (3) 0.6 (3) T. moseri ÑÑÑÑÑÑÑÑÑÑ T. n.sp. 3 Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ T. n.sp. 12 Ñ Ñ Ñ 0.1 (1) 0.1 (1) Ñ Ñ Ñ Ñ T. parisiana 4.1 (15) Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ URO Uroobovella ÑÑÑÑ0.4 (5) Ñ Ñ Ñ 8.9 (151) Ñ americana U. dryocoetes ÑÑ17.6 (6) Ñ 1.6 (35) Ñ Ñ Ñ 0.5 (2) 0.3 (1) U. orri Ñ 4.5 (1) Ñ Ñ Ñ Ñ Ñ Ñ Ñ 0.6 (4) U. vinicolora ÑÑÑÑÑÑÑÑ0.5 (2) Ñ ORB Paraleius 0.4 (1) Ñ Ñ Ñ 0.5 (7) Ñ Ñ Ñ 0.7 (3) 0.9 (3) leontonycha P. n.sp. Ñ Ñ Ñ Ñ 5.2 (100) Ñ Ñ Ñ 10.1 (76) Ñ Total Beetle abundance 241 22 34 801 1,124 48 19 1 405 325 no. mite species 4115175111711 (33) Mite abundance 18 1 6 7 269 35 3 1 449 42 (2,424) Mite prevalence 5.4 4.5 17.6 0.9 12.4 37.5 10.5 100 38.0 9.5 (%) most abundant species across all sites in 2008 and 2009, diversity (both with 17 species) (Table 2). Ips grandi- respectively (Table 1). The majority of beetle indi- collis (Eichhoff), the fourth most abundant beetle, viduals were collected from Algonquin PP in 2008 also showed a high-mite diversity (11 species) despite (89%) and 2009 (87%), and species diversity was also a relatively lower mite abundance and prevalence highest in Algonquin in both years (Table 1). (Table 2). D. valens, Hylurgops pinifex Wood & Bright, Across all sites and both years, 12% of the 4,006 and I. pini had the highest mite prevalence (35Ð38%; beetles examined had at least one mesostigmatic or Table 2). oribatid mite (hereafter mites), and of the 29 host In total, 1,025 mites representing 33 species, eight species examined, only 17 species (13 genera and nine genera and seven families (six of Mesostigmata, one of tribes) had mites (Table 1). Overall prevalence was Oribatida), were collected across all sites and both higher in 2009 than in 2008 (13.5 and 10%, respec- years (Table 2). Site N1 in 2008, was the most species tively). Nine bark beetle species (242 individuals) that rich site, with 26 mite species from seven genera and feed on deciduous hosts were collected (Table 1), seven families (Supp. Table 1 [available online only]). three of which had mites with an overall prevalence of 2.8% (0.8Ð25%). In total, 19 conifer-feeding bark bee- Sites outside of Algonquin PP were poor: in 2008 sites tle species (3,706 individuals) were collected (Table S1 and S2 had only six and two species, respectively, 1), 14 of which had mites with an overall prevalence and in 2009 sites S3 and S4 also had only one and two of 12.4% (0.4Ð38%); more than four times higher than species, respectively (Supp. Table 1 [available online on bark beetles from deciduous hosts. The host asso- only]). The was the most abundant ciations of one species, Pityophthorus sp., are unknown and diverse family, with 11 species (two genera) and because members of this may feed on deciduous 39% (395 mites) of all mite individuals collected (Ta- or coniferous trees (Wood 1982). D. valens and H. ble 2). Also abundant and diverse were the Urod- porculus, two of the three most abundant beetle spe- inychidae (241 mites, four species), (88 cies, exhibited the highest mite abundance (43.8 and mites, nine species), and Melicharidae (94 mites, Þve 26.2% of all mites collected, respectively) and mite species) (Table 2). Oribatulidae (194 mites, two spe- May 2013 KNEE ET AL.: HOST USE OF MITES PHORETIC ON BARK BEETLES 343

Table 2. Continued

c Orthotomicus Pityogenes Pityokteines Polygraphus Xyleborus Trypodendron b Xyloterinus Total mite No. of host I. pini I. pini caelatus hopkinsi sparsus rufipennis sayib lineatum T. retusum politusb,c abundance speciesd

ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 85 ÑÑ0.3 (1) Ñ Ñ Ñ Ñ Ñ Ñ Ñ 55 7

ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 31 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 158 3 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 28 2 Ñ 0.1 (1) Ñ Ñ Ñ Ñ Ñ 0.4 (1) Ñ Ñ 2 2 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 11 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 11 ÑÑ18.1 (112) 4 (3) Ñ Ñ Ñ Ñ Ñ Ñ 115 2 17.2 (18) 30.2 (1,302) Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 1,324 2 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 104 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 11 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 52 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 20 1 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 62 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 72 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 60 1 ÑÑ0.3 (1) Ñ Ñ Ñ Ñ Ñ Ñ Ñ 1 1 17.2 (14) 4 (86) Ñ Ñ Ñ Ñ Ñ Ñ Ñ 1 (1) 109 4

ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 41 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 41 0.1 (2) Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 29 5 ÑÑ Ñ Ñ Ñ Ñ0.8 (1) Ñ Ñ Ñ 9 4 ÑÑ Ñ Ñ12.5 (1) 2.4 (1) Ñ Ñ Ñ Ñ 2 2 ÑÑ Ñ6 (3) Ñ Ñ Ñ Ñ Ñ Ñ 3 1 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 22 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ25 (1) Ñ 16 2 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 156 2

ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 44 4 ÑÑ4.4 (21) Ñ 12.5 (2) 7.1 (11) Ñ Ñ Ñ Ñ 39 5 ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 21 Ñ 0.4 (6) 1.3 (4) Ñ Ñ Ñ Ñ Ñ Ñ Ñ 24 6

ÑÑ Ñ Ñ Ñ Ñ Ñ Ñ Ñ Ñ 176 2 29 1415 298 50 8 42 118 265 4 98 25 52221111

32 1397 139 6 3 12 1 1 1 1

34.5 32.7 22.1 10 25 9.5 0.8 0.4 25 1

a AMR, ; DGM, Digamasellidae; MAC, Macrochelidae; MLC, Melicharidae; TRM, Trematuridae; URO, ; ORB, Oribatulidae. b Scolytine species associated with deciduous host species, all other species are associated with coniferous hosts (Wood 1982). c Traps baited with Ips pini pheromone lures. d Species with abundance Ն20 in bold. cies) and Macrochelidae (5 mites, one species) were zeburg)) (excluding the instances with Ͻ5 beetles the least diverse (Table 2). collected) (Table 2). Also from traps with general Typically, only one mite individual, occasionally lures, the most frequently collected mite species two, were collected per beetle (58 and 19% of all were Paraleius n.sp. (Oribatulidae) (17.2% of all beetles with mites, respectively); more rarely, 3 (7%), mites collected), Dendrolaelaps n.sp. 1 (15.4%), 4 (7%), or 5Ð11 mites (9%) were found on an indi- Uroobovella americana Hirschmann (15.2%), and D. vidual beetle. Most bark beetle individuals with mites quadrisetosimilis (11.2%) (Table 2). Uroobovella were associated with only one mite species (84%); orri Hirschmann was collected from Þve host spe- fewer had two (12%) or three species (3%), and the cies (three tribes), and it was relatively common on maximum was four species collected from a single D. two of these hosts, Orthotomicus caelatus and valens specimen. D. valens reached an exceptionally Polygraphus rufipennis (Kirby) (Table 2). It should high number of mites, with 24, 27, and a maximum of be noted that the specimens from O. caelatus may not be 29 mites per host, and a single individual had as much U. orri, but instead they may represent a cryptic species, as four species of mites. Uroobovella n.sp. 6 (sensu Knee et al. 2012b), which is From traps with general lures, the mites with the primarily detectable by molecular methods. highest prevalence on a given beetle species were Most mite species showed minimal variation in total Dendrolaelaps n.sp. 2 (22.9% prevalence on Hylurgops abundance, prevalence or mean intensity across sites pinifex), Dendrolaelaps n.sp. 1 (18.3% on D. valens), D. or years, with the exception of a few species. Dendro- quadrisetosimilis Hirschmann (18.1% on Orthotomicus laelaps n.sp. 1 showed an approximately threefold in- caelatus (Eichhoff)), and Uroobovella dryocoetes crease (8.6Ð29.4%) in prevalence on D. valens from (Vitzthum) (17.6% on Dryocoetes autographus (Rat- 2008 to 2009 in site N2, as well as an eightfold increase 344 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 106, no. 3

Fig. 1. Distribution of the breadth of host range of mites collected from bark beetles sampled across four sites in eastern Ontario, for all 33 mite species collected (black), and only for the 21 species with an abundance Ն5 (gray). in total abundance from 2008 to 2009 (Supp. Table 1 Host Range and Variation With Published Host [available online only]). Paraleius n.sp. associated Records. Mite species were found on an average of with D. valens showed more than a fourfold increase 2.5 Ϯ 1.7 (SD) beetle species (pooled data from gen- (4.3Ð18.6%) in prevalence, and a 14 times increase in eral and pheromone speciÞc traps). Most mite species abundance in site N2 from 2008 to 2009 (Supp. Table had a narrow host range, occurring on one (33.3%) or 1 [available online only]). The prevalence of Dendro- two (36.4%) host species; much fewer species had a laelaps quadrisetosimilis increased from 8.3 to 20.5% in broader host range occurring on three (3%), four site N2 from 2008 to 2009 (Supp. Table 1 [available (12.1%), Þve (9.1%), or six (3%) host species; Den- online only]). In contrast, the prevalence of D. drolaelaps hexaspinosus Hirschmann, was found on quadrisetosimilis on O. caelatus dropped from 20.4 to seven host species (Fig. 1). After removing mite spe- Ͻ 6.7%, and its abundance dropped from 68 to 2, in site cies with an overall abundance 5, the average num- Ϯ N1 from 2008 to 2009 (Supp. Table 1 [available online ber of host species per mite species increased to 3.2 only]). 1.7; also, there were still slightly more mites with one I. pini Pheromone Traps. In total, 1,629 bark beetles or two hosts (52.4%) than those with three or more from 19 species, 15 genera, and 8 tribes, were collected host species (47.6%), but only two species (9.5%) had in traps baited with I. pini pheromone lures, across a single host (Fig. 1). Beyond the species level, there four sites in 2008 (Table 1). I. pini represented 86.9% was no apparent speciÞcity of mite taxa toward par- of all beetles collected in these pheromone lure traps. ticular beetle taxa: each mite family and most genera were found on at least two tribes and two genera From a total of 19 beetle species collected, only three (Table 2). species had mites (Table 1). In total, 1,399 mites rep- We assessed the degree of host speciÞcity of rela- resenting six species, three genera, and three families, tively common mites (those with an abundance Ն20) were collected (Supp. Table 1 [available online by considering, Þrst the number of host species ex- only]). Five of the six mite species collected were ploited, and second, the prevalence and abundance on found on I. pini, which had an overall mite prevalence a given host species. Among the 14 mite species with of 32.7% (Supp. Table 1 [available online only]). an abundance Ն20, eight appeared to be more or less Dendrolaelaps quadrisetus (sensu Hirschmann host speciÞc, and six had a broad host range (Table 2). 1960) and Trichouropoda australis Hirschmann, were Of the eight Ôhost-speciÞcÕ species, seven were col- collected from I. pini in all four sites in 2008 (Supp. lected from one or two hosts, and six of these species Table 1 [available online only]). D. quadrisetus had showed a strong preference for a single host species, the highest prevalence (20Ð33.5%), abundance (93% being much more prevalent and abundant on that host of all individuals), and mean intensity (3.2/beetle), (Dendrolaelaps n.sp. 2, D. quadrisetosimilis, D. whereas T. australis had the second highest preva- quadrisetus, Proctolaelaps fiseri Samsina´k, P. n.sp. 2, U. lence (3Ð4.7%), abundance (6%), and mean intensity americana). Paraleius n.sp. exhibited a strong prefer- (1.9/beetle) (Supp. Table 1 [available online only]). ence for two host species, H. porculus and D. valens, Combined across traps with general lures and those which both live in the stumps and roots of dead or with I. pini pheromone lures, a total of 5,635 bark dying conifers (Wood 1982). Dendrolaelaps n.sp. 1 was beetles from 30 species were collected, and 16.4% of found on three hosts, but this mite was almost exclu- these hosts had at least one mite. In total, 2,424 mites sively collected from D. valens, and rarely (one in- from 33 species, including 12 new species, were col- stance each) from its two other hosts (Table 2). The lected from both trapping methods. six remaining species were found on 4Ð7 hosts, and May 2013 KNEE ET AL.: HOST USE OF MITES PHORETIC ON BARK BEETLES 345 these species did not exhibit any clear host preference, the declivity), and 9% on the head or pronotum. Ori- with the exception of T. australis (Table 2). T. australis batids were also typically located on ventral surfaces was collected from four hosts, and did show a pref- of their hosts, with 86% on the ventral prothorax, 12% erence for I. pini (even when excluding data from I. on the ventral meso- or metathorax, and 2% on the pini pheromone traps); however, this mite is not a elytral declivity. strict host specialist, not even locally, and has been found frequently on I. grandicollis and rarely on Ips Discussion perturbatus (Eichhoff) in Ontario and Quebec (Knee et al. 2012b). A rich assemblage of mites was found on bark bee- The host records for the 21 described species col- tles in Ontario, with 33 species and 7 families of mites lected in this study increased considerably, from 186 collected from 18 host species from only six sites. records to 221 (19% increase; Table 3). Combined Considering that two major groups of Acari (Prostig- across the literature and this study, the described mata, Astigmata) were not studied here, our Þndings species were found on an average of 10.5 Ϯ 6.6 beetle represent only a fraction of the scolytine-associated species, with a maximum of 26 hosts for D. quadrisetus mites in the region. The prevalence of mites varied (Table 3). Most (60%) of the host associations ob- substantially among hosts. For instance, D. valens, I. served in this study represent new records. Novel host pini, O. caelatus, and H. pinifex, frequently carried records were reported for 17 of the 21 described spe- mites (22Ð38% of beetles), whereas other host species, cies collected (Table 3). More importantly, there was such as , Xyleborus sayi (Hopkins), and little overlap in bark beetle hosts between this study Trypodendron lineatum (Olivier), were virtually de- and the literature for many of the most common spe- void of mites (0.4Ð0.9%). This apparent rarity of mites cies (e.g., D. quadrisetus, D. quadrisetosimilis, T. aus- is probably not due to a lack of sampling, since some tralis, and U. americana each with only 0Ð2 host spe- of the relatively mite-free beetle species were fairly cies shared; Table 3). common (e.g., H. opacus and T. lineatum). Therefore, The host range breadth of several mite species col- ecological factors such as beetle microhabitat, behav- lected in this study differed from that of published host ior or phenology, may favor certain host associations. records (Table 3). Dendrolaelaps neodisetus Hurlbutt, Studies on scolytine-associated mites often ignored D. quadrisetosimilis, and D. quadrisetus, were each potential associations with other families of wood- collected from few host species (one or two) in this boring beetles. Overall, mites associated with scolyt- study, suggesting that these mites are relatively host ines are infrequently collected from other families of speciÞc; however, according to published host records wood-boring beetles, with the exception of a few spe- these mites are host generalists (Table 3). In contrast, cies (Kinn and Linit 1989). In this study, four species, D. quadritorus Robillard, appeared to be more gener- D. neodisetus, L. cunicularius Chant, T. hirsuta alized in this study (four host spp. in three genera) Hirschmann, and T. lamellosa Hirschmann, are not than in the literature (only two Ips spp. from Louisi- scolytine specialists but are actually primarily associ- ana). Proctolaelaps fiseri and P. hystrix (Vitzthum) ated with cerambycids (Chant 1961, Kinn 1987, Kinn both appeared to be host speciÞc in this study, while and Linit 1989, Moser and Roton 1971). in the literature these two species are apparent host Host Specificity, Locally, and Globally. The major- generalists (Table 3). Similarly, T. fallax (Vitzthum) ity of mites (23 of 33 spp.) were collected from only and U. americana were collected from one to two host one or two host species, with the remainder associated species in this study, whereas published records sug- with 3Ð7 hosts. This seemingly high host speciÞcity is gest that these two species are host generalists (each in part because of the low abundance of some mites. seven host spp. in three genera). Indeed, the removal of mite species with fewer than Phoretic Attachment Location. The attachment lo- Þve individuals collected dropped the number of cation of mites indicates that different groups of mites mites with a narrow host range (1Ð2 hosts) from 23 to attach to different locations on host beetles. Mites 11 species, with only two remaining mite species being from the Order Mesostigmata, excluding monospeciÞc. Nevertheless, our data suggests that Uropodoidea, were collected almost exclusively from several of these 11 species may have a preference for under the elytra of their hosts, with 97.2% of mites a single host, or two, at least at a local scale. under the elytra, 0.5% on the dorsal surface of the The mites collected in this study represent a elytra, 1% on the ventral thorax or abdomen, 0.8% on mixed assemblage of predators, fungivores, omni- the legs, and 0.5% on the head or pronotum of their vores, and scavengers (Kinn 1967, 1982, 1987; Moser hosts. However, the usage of a liquid preserva- 1975). Since these mites are not parasitic (therefore tive may have biased the attachment location of some not closely associated with their host physiology) mesostigmatic mites (excluding uropodoids) by dis- and are presumably primarily associated with bark lodging mites that were not under the elytra. beetles for phoretic dispersal to new subcortical Uropodoids (Trematuridae, Urodinychidae) were habitats (Lindquist 1970), there may be little selec- most often found glued with their anal pedicel to tion for host speciÞcity, and any bark beetle species ventral surfaces of their hosts: 55% on the ventral encountered could serve as a potential phoretic thorax or abdomen, and 9% on the legs. Uropodoids carrier. To some extent, the Þndings of this study were also found on dorsal surfaces of their hosts: 20% contradict this hypothesis. Among the 14 most com- on the elytral declivity, 7% on the elytra (excluding monly collected mite species, six species appear to 4 A 346

Table 3. Comparing observed host records (this study) with published records (publ.) for the 21 described mite species collected from scolytines and other families of wood-boring beetles across (.four sites in eastern Ontario (the no. of ؉ indicates the no. of shared host spp

No. host spp./genera Mite species Published host species (Њspp. shared with present study) Regionsb References This study Publ. Dendrolaelaps hexaspinosus 7/6 6/6 Cryphalus piceae, Dryocoetes autographus, Hylurgops palliatus, Austria, Poland, Hirschmann and WiÏniewski 1982 ligniperda, Pityogenes quadridens, Tomicus Ukraine piniperda D. louisianae 1 1 CURa: Hylobius pales LA Hirschmann and WiÏniewski 1982 ϩ THE OF NNALS D. neodisetus 115/7 Dendroctonus brevicomis, D. frontalis, D. simplex, D. terebrans, AB, ON; AZ, Hofstetter 2008; Hurlbutt 1967; D. valensЊ, Ips avulsus, I. grandicollis, I. pini; CER: CA, MS, LA, Kinn and Linit 1989; Knee et al. Monochamus carolinensis, M. scutellatus, M. titillator, TX; Honduras 2012a; McGraw and Farrier Neacanthosinus obsoletus; BUP: Buprestis lineata; CUR: 1969; Moser and Roton 1971 Hylobius pales; TRO: Temnochila virescens D. quadrisetosimilis 2/2 5/4 Dryocoetes autographus, Ips avulsus, I. calligraphus, AB; LA; Poland, Hirschmann and WiÏniewski

Pityokteines minutus, Germany 1982; Hurlbutt 1967; Moser and E Roton 1971 NTOMOLOGICAL ϩϩ D. quadrisetus 2/1 26 /7 Dendroctonus adjunctus, D. brevicomis, D. frontalis, D. AK, AZ, CA, ID, Cardoza et al. 2008; Hirschmann pseudotsugae, D. rufipennis, D. terebrans, D. valens, NC, PA, VA; 1960; Hirschmann and Dryocoetes confusus, Hylastes cunicularius, H. opacus, H. Croatia, WiÏniewski 1982; Hofstetter palliatus, Ips avulsus, I. calligraphus, I. confusus, I. France, 2008; Hurlbutt 1967; Kinn 1967; grandicollisЊ, I. latidens, I. piniЊ, I. plastographus, I. Germany, Levieux et al. 1989; McGraw ponderosa, I. sexdentatus, punctatus, P. sequoiae, Switzerland and Farrier 1969; Moser and Pityokteines curvidens, P. spinidens, P. vorontzowi, Tomicus Bogenschutz 1984; Pernek et al. S CEYOF OCIETY piniperda 2008 ϩ D. quadritorus 4/3 2 /1 Ips avulsus, I. grandicollisЊ LA Robillard 1971 Longoseius cuniculus 1 11/5 Dendroctonus approximatus, D. frontalis, Ips avulsus, I. AZ, LA, ME, Chant 1961; Hofstetter 2008; calligraphus, I. grandicollis; CER: Monochamus carolinensis, MS, NC, TX, Hurlbutt 1967; Kinn 1987;

M. notatus, M. scutellatus, M. titillator, Neacanthosinus VA McGraw and Farrier 1969; A

obsoletus; CLR: Thanasimus dubius Moser and Roton 1971; Soper MERICA and Olsen 1963 Proctolaelaps fiseri 1 10/8 Dendroctonus valens, Dryocoetes sp., Ernoporus sp., AZ, GA, LA; Hirschmann and Ru¨ hm 1953; Gnathotrichus materiarius, Hylurgops sp., Ips avulsus, I. Germany Hofstetter 2008; Lindquist and calligraphus, I. typographus, Pityokteines sp., Tomicus sp. Hunter 1965; Moser and Roton 1971; Westerboer 1963 ϩ P. hystrix 2/2 8 /4 Dendroctonus frontalis, D. micans, D. terebrans, D. valensЊ, AZ, CA, LA; Hofstetter 2008; Lindquist and Dryocoetes autographus, Hylastes ater, Ips calligraphus, I. Austria, Hunter 1965; Moser and Roton pini Poland 1971 ϩϩ Trichouropoda australis 4/3 17 /3 Dendroctonus brevicomis, D. frontalis, D. ponderosae, D. NS, ON, QC; AZ, Hofstetter 2008; Kinn and Linit simplex, D. terebrans, Ips avulsus, I. bonanseai, I. FL, LA, MS, 1989; Knee et al. 2012b; Moser calligraphus, I. confusus, I. cribricollis, I. grandicollisЊ,I. NM, NY, RI, and Roton 1971 hunteri, I. lecontei, I. perturbatus, I. pilifrons, I. piniЊ; CER: TX; Mexico

Neacanthosinus obsoletus 3 no. 106, Vol. T. bipilis 11Scolytus pygmaeus Austria Hirschmann and WiÏniewski 1989 ϩ T. fallax 17/3 Dendroctonus adjunctus, Hylastes ater, H. cunicularius, H. BC, NS; LA, UT; Hirschmann and WiÏniewski interstitialis, H. ruber, Hylurgops pinifexЊ, H. rugipennis Siberia; 1989; Hofstetter 2008; Knee et pinifex Belgium al. 2012b a 03K 2013 May

Table 3. Continued

No. host spp./genera Mite species Published host species (Њspp. shared with present study) Regionsb References This study Publ. ϩϩϩ T. hirsuta 5/4 17 /9 Dendroctonus approximatus, D. brevicomis, D. frontalis, D. AB, ON, QC, NS; Hirschmann and WiÏniewski valensЊ, Dryocoetes affaber, Gnathotrichus materiarius, Ips AZ, LA, MS, 1986; Hofstetter 2008; Kinn and

avulsus, I. calligraphus, I. grandicollisЊ, I. piniЊ, Polygraphus TX Linit 1989; Knee et al. 2012a, b; AL ET NEE rufipennis, Trypodendron scabricollis; CER: Monochamus Moser and Roton 1971 carolinensis, M. scutellatus, M. titillator, Neacanthosinus obsoletus, Xyloterus sagittatus ϩ T. lamellosa 4/4 11 /6 Dendroctonus ponderosae, D. pseudotsugae, Dryocoetes AB, ON; AZ, LA, Hofstetter 2008; Kinn 1987; Kinn confusus; Ips avulsus, I. calligraphus, I. grandicollisЊ; CER: MS and Linit 1989; Knee et al. H .:

Monochamus carolinensis, M. scutellatus, M. titillator, 2012a, b; Moser and Roton 1971 OST Neacanthosinus obsoletus, Xyloterus sagittatus ϩ

T. moseri 2/2 2 /2 Dendroctonus simplex, Polygraphus rufipennisЊ AB, QC Hirschmann 1972; Knee et al. U

2012b OF SE ϩ T. parisiana 2/2 4 /3 Gnathotrichus materiariusЊ, Ips sexdentatus, I. typographus, BC, QC, NS; MI; Hirschmann and WiÏniewski Xyleborinus saxesenii France 1987, Knee et al. 2012b

ϩ M Uroobovella americana 2/2 7 /3 Dendroctonus pseudotsugae, D. terebrans, D. valensЊ, QC; AZ, LA, Hofstetter 2008; Knee et al. 2012b; Gnathotrichus materiarius, Ips avulsus, I. calligraphus, I. OH, PA, WI Moser and Roton 1971 ITES grandicollis

ϩϩϩ P U. dryocoetes 4/4 7 /5 Dendroctonus valensЊ, Dryocoetes affaber, D. autographusЊ, NB, NS, QC; Hirschmann 1989; Knee et al. OEI ON HORETIC Hylastes cunicularius, H. porculusЊ, Ips sexdentatus, Austria 2012b Polygraphus rufipennis ϩϩϩϩ U. orri 5/5 18 /6 Dendroctonus brevicomis, D. frontalis, D. obesus, D. AB, ON, NS, QC; Hofstetter 2008; Knee et al. 2012b; pseudotsugae, D. rufipennis, D. valens, Dryocoetes affaberЊ, AZ, CA, LA, Moser and Roton 1971 D. confusus, Gnathotrichus materiarius, Ips avulsus, I. MS, TX;

calligraphus, I. emarginatus, I. grandicollisЊ, I. pini, I. Croatia B plastographus, Pityokteines curvidens, P. sparsusЊ, ARK Polygraphus rufipennisЊ

ϩ B U. vinicolora 13/3 Dendroctonus valensЊ, Hylurgops sp., Ips typographus CA; Germany, Knee et al. 2012b; Moser and EETLES Mexico Bogenschutz 1984 Paraleius leontonycha 6/5 8/4 Dendroctonus frontalis, Dryocoetes affaber, D. confusus, AK, AZ, LA, Hofstetter 2008; Norton 1980; Hylastes nigrinus, H. salebrosus, Pityokteines curvidens, P. OR; Austria, Pernek et al. 2008, 2012 spinidens, P. vorontzowi Croatia

a BUP, Buprestidae; CER, Cerambycidae; CLR, Cleridae; CUR, Curculionidae; TRO, Trogossitidae. b Provinces and states of Canada and the United States follow accepted abbreviations. 347 348 ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA Vol. 106, no. 3 have a broad host range (Ն4 hosts, from Ն3 genera), Sˇimkova´ et al. 2006), as suggested here for several mite with no sign of host preferences, whereas eight species phoretic on bark beetles. species showed a marked preference for one or two Challenges of Host Specificity Studies. The host hosts. Moreover, four of the Þve most common spe- range differences between this study and the liter- cies (Dendrolaelaps n.sp. 1, D. quadrisetus, D. ature is signiÞcant: 60% of the mite-host associations quadrisetosimilis, and U. americana) were primarily recorded for described species in this study are associated with a single host species. The other most novel, and 88% of previously published associations common species, Paraleius n.sp., was exclusively for described species were not found in this study. collected from two unrelated hosts that occupy sim- The absence of overlapping records between this ilar habitats (Wood 1982). If these results represent study and the literature is in part because of most actual host preferences, then there has been some published records being from Europe and southern form of selection for host speciÞcity. United States, where the bark beetle fauna differs In contrast, when published host records are considerably from that of Ontario, as well as because taken into consideration, strict host speciÞcity ap- of variation in sampling techniques across studies. pears to be rare. The combined host records from This also shows the dearth of sampling in Canada this study and the literature indicate that the ma- and most regions of United States. Indeed, most jority of the 21 described species collected here scolytine species have not been studied for mites, have a broad host range (up to 26 host spp.); with and those that have been were typically done so the most host-speciÞc mites (four species) having locally. Therefore, current host records represent two to three hosts representing two to three genera. the tip of the iceberg. The lack of such baseline data According to published host records, all of de- on host associations obfuscates any analyses of host scribed species that were relatively common (10 speciÞcity. spp. with at least 20 individuals collected) in this The observed discrepancies in host range breadth study have a broad host range. Unfortunately, most may not only reßect natural geographic variation in published surveys do not provide prevalence or host preferences, but also some of the challenges abundance data, making it almost impossible to dis- inherent to the study of host speciÞcity. Clear and criminate between strong and loose or accidental stable species concepts, as well as accurate taxo- nomic identiÞcations are the buttresses of any bio- host associations. diversity or ecological study, but particularly to The host records from the literature and the Þnd- studies focusing on host associations. Parasite and ings of this study together suggest that at a global scale symbiont identiÞcations have historically been ex- bark beetle-associated mites have a broad host range, clusively based on morphological characters. How- while at a local scale many species tend to be host ever, the latter may alone be insufÞcient for delin- speciÞc. For instance, P. fiseri was reported from 10 eating species boundaries in groups that include different host species from eight genera, in southeast- cryptic species (Poulin and Keeney 2007), which ern United States and Germany. In Ontario, we found are distinguished by no or subtle morphological P. fiseri only on one host species, H. porculus. Similarly, differences. It is possible that the observed differ- D. quadrisetus was found on 26 scolytine species from ences in host range breadth of bark beetle mites are seven genera across United States and Europe; a result of unrecognized cryptic diversity, in which whereas in Ontario, we collected it primarily on I. pini, putatively widespread generalists (e.g., D. quadrise- and rarely from the congeneric I. grandicollis. At a tus) represent complexes of cryptic species with local scale, many of these mites appear to be primarily relatively narrow host preferences. For example, associated with a single bark beetle species, despite morphological and molecular analyses revealed that the availability of many other hosts. Therefore, non- a single generalist uropodoid species, Uroobovella parasitic mite species may be host speciÞc and not, or nova (Oudemans), associated with silphid beetles, is at least not only, habitat speciÞc. Host speciÞcity to actually a complex of cryptic species with varying one group of phoretic carrier (e.g., to a family or genus degrees of host speciÞcity (Knee et al. 2012c). of insects) is common in mite taxa associated with Poorly understood taxonomy can easily lead to in- patchy habitats (e.g., carrion, dung, fungal fruiting accurate species level identiÞcations by both experts bodies; OConnor 1982, Krantz 1998), but there are few and nonexperts. For example, several publications on well studied cases that show high host speciÞcity. For Mucroseius (Melicharidae), a genus of mites associ- example in Mesostigmata, species complexes of ated with cerambycid beetles, contained several in- Poecilochirus (Parasitidae) and Uroobovella (Urod- correctly identiÞed species, which were uncovered by inychidae) appear to prefer one species or a few spe- Lindquist and Wu (1991). In addition, before the re- cies of Nicrophorus (Silphidae) beetles (Brown and vision of the genus (Dermanyssidae), Wilson 1992, Knee et al. 2012c). Between geographic many researchers misidentiÞed various Dermanyssus regions populations may be differentially constrained species as D. gallinae (De Geer) (Moss 1978). Species by variation in local host availability, and by local identiÞcations in biodiversity studies are frequently adaptation to biotic or abiotic factors (Poulin 2007). performed by nonspecialists, sometimes with minimal This variation through space could explain why a given support from taxonomic experts, inevitably leading to symbiont may be a host specialist at a local scale and occasional erroneous identiÞcations. Even so, there a generalist at a global scale (Krasnov et al. 2004, 2011; are instances where specialists, with decades of expe- May 2013 KNEE ET AL.: HOST USE OF MITES PHORETIC ON BARK BEETLES 349 rience on a particular group have difÞculty correctly Hirschmann, W. 1989. Gangsystematik der diagnosing specimens to species (Packer et al. 2009). Teil 509: die Ganggattung Uroobovella Berlese 1903. Ac- Naturally, incorrect identiÞcations are much more arologie 36: 84Ð196. likely in taxa for which there are few or no dichoto- Hirschmann, W., and W. Ru¨ hm. 1953. Milben und Faden- mous keys or reliable species descriptions, as seen in wu¨ rmer als Symphoristen und Parasiten des Buchdruck- ers. Mikrokosmos 43: 7Ð10. many groups of symbiotic taxa (Kijewska et al. 2002, Hirschmann, W., and W. Ru¨ hm. 1955. Ein “Haustier” des Locke et al. 2010). Interpreting host speciÞcity across Buchdruckers? Mikrokosmos 44: 234Ð236. studies can be severely hampered by these sometimes Hirschmann, W., and J. Wiœniewski. 1982. Weltweite re- rampant misidentiÞcations. vision der Gattungen Dendrolaelaps Halbert 1915 und Changes in species concepts through time, or Longoseius Chant 1961 (Parasitiformes). Band II. Ac- among authors, can further obscure host speciÞcity arologie 29: 1Ð48, 1Ð94 pl. estimates. For instance, D. quadrisetus and D. Hirschmann, W., and J. Wiœniewski. 1986. Gangsys- quadrisetosimilis are currently considered distinct tematik der Parasitiformes Weltweite Revision der species, but historically D. quadrisetosimilis was syn- Gattung Trichouropoda Berlese 1916 Tiel I. Acarologie onymized under D. quadrisetus (McGraw and Farrier 33: 1Ð181. Hirschmann, W., and J. Wiœniewski. 1987. Gangsystematik 1969). Unfortunately, ßuctuations and disagreements in der Parasitiformes Weltweite Revision der Gattung species concepts are present in virtually all groups of Trichouropoda Berlese 1916 Tiel II. Acarologie 34: 1Ð180. arthropods. Hopefully, more reÞned systematic tools, Hirschmann, W., and J. Wiœniewski. 1989. Gangsystematik such as improved microscopy techniques, and the use of der Parasitiformes Teil 507Ð508: Weltweite Revision der currently available and novel molecular markers, will Gattung Trichouropoda Berlese 1916 Teil IV. Acarologie bring relative stability to species concepts. 36: 1Ð72. Hirschmann, W., and I. Zirngiebl–Nicol. 1961. Gangsys- tematik der Parasitiformes Teil 4: die Gattung Trichou- ropoda Berlese 1916 nov. comb., die Cheliceren und das Acknowledgments System der Uropodiden. Acarologie 4: 1Ð41, 1Ð16 pl. Hofstetter, R. W. 2008. Information and images of mites We are grateful to E. Lindquist, G. Krantz, V. BehanÐ associated with bark beetles and their predators. (http:// Pelletier, and D. Walter for their advice and assistance with .ucc.nau.edu/rh245/MiteImages.htm). mite identiÞcations, as well as H. Douglas for his help with Hurlbutt, H. W. 1967. Digamasellid mites associated with scolytine identiÞcations. We thank T. Hartzenberg, H.W. bark beetles and litter in North America. Acarologia 9: Knee, and R. Shewchuk for their help in the Þeld and the lab, 497Ð534. as well as the private land owners who permitted sampling on Kijewska, A., J. Rokicki, J. Sitko, and G. Weˆgrzyn. 2002. their property. We also thank E. 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