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Ectoparasites of rabbits and hares in Manitoba, Canada, with observations on age-specific dispersal in Haemodipsus setoni (Phthiraptera: Anoplura: Polyplacidae)

Published online by Cambridge University Press:  28 May 2012

Terry D. Galloway
Terry D. Galloway*
Affiliation:
Department of Entomology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2 (e-mail: Terry_Galloway@umanitoba.ca).
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Abstract

During 1994–2008, 58 adult and 195 juvenile eastern cottontail rabbits (Sylvilagus floridanus (Allen)), one adult and 23 juvenile snowshoe hares (Lepus americanus Erxleben), and eight adult white-tailed jackrabbits (Lepus townsendii Bachman) (Mammalia: Leporidae) were examined for ectoparasites. The most abundant ectoparasite on cottontails was the sucking louse, Haemodipsus setoni Ewing (Phthiraptera; Polyplacidae), recorded from this host for the first time. Infestations in adult and juvenile cottontails were highly aggregated, k = 0.136 and 0.153, respectively. Prevalence of infestation in adult cottontails was 70.6%, with a mean intensity of 5614.1 (range: 1–166 249); 10 adults had more than 1000 lice. In juvenile cottontails, prevalence was 34.8% and mean intensity was 6.2 (range: 1–87). On adult cottontails, 73.4% of the total lice were nymphs, while on juvenile cottontails only 11.6% were nymphs. It appears that dispersal from parents to offspring is overwhelmingly achieved by adult lice. Seventeen adult cottontails were infested with the tick, Haemaphysalis leporispalustris (Packard) (Acari: Ixodidae). No fleas specific to rabbits were collected but small numbers of the rodent fleas Monopsyllus vison (Baker), Orchopeas caedens (Jordan), and Aetheca wagneri (Baker) (Siphonaptera: Ceratophyllidae) were recorded. Only one snowshoe hare was infested with H. setoni and three were infested with H. leporispalustris; no fleas were found on snowshoe hares. Two white-tailed jackrabbits were infested with H. leporispalustris; one carried Pulex irritans Linnaeus (Siphonaptera: Pulicidae), and none carried lice.

Résumé

De 1994 à 2008, nous avons recherché les ectoparasites sur 58 adultes et 195 jeunes du lapin à queue blanche (Sylvilagus floridanus (Allen)), un adulte et 23 jeunes du lièvre d'Amérique (Lepus americanus Erxleben) et huit adultes du lièvre à queue blanche (Lepus townsendii Bachman) (Mammalia: Leporidae). L'ectoparasite le plus abondant sur les lapins est le pou suceur Haemodipsus setoni Ewing (Phthiraptera: Polyplacidae), signalé sur cet hôte pour la première fois. Les répartitions des infestations chez les lapins adultes et jeunes sont fortement contagieuses, les valeurs respectives de k étant 0,136 et 0,153. La prévalence de l'infestation est de 70,6% chez les lapins adultes avec une intensité moyenne de 5614,1 (étendue: 1–166 249); 10 adultes portaient plus de 1000 poux. Chez les jeunes lapins, la prévalence est de 34,8% et l'intensité moyenne de 6,2 (étendue: 1–87). Chez les lapins adultes, 73,4% de l'ensemble des poux sont des larves, alors que les larves ne représentent que 11,6% sur les jeunes lapins. Il apparaît donc que la dispersion des parents vers les jeunes se fait surtout par les poux adultes. Dix-sept des lapins étaient infestés par la tique Haemaphysalis leporispalustris (Packard) (Acari: Ixodidae). Aucune puce spécifique aux lapins n'a été récoltée, mais de petits nombres de puces des rongeurs Monopsyllus vison (Baker), Orchopeas caedens (Jordan) et Aetheca wagneri (Baker) (Siphonaptera: Ceratophyllidae) ont été retrouvés. Un seul lièvre d'Amérique était infesté par H. setoni et trois portaient des H. leporispalustris; aucune puce n'a été récoltée sur les lièvres d'Amérique. Deux lièvres à queue blanche étaient infestés par H. leporispalustris; un portait Pulex irritans Linnaeus, mais aucun n'avait de puces.

Information

Type
Original Article
Information
The Canadian Entomologist , Volume 144 , Issue 3 , 28 May 2012, pp. 439 - 446
Copyright
Copyright © Entomological Society of Canada 2012

Introduction

Rabbits are important herbivores in many ecosystems and they may constitute primary prey species for many mammalian and avian predators. They represent a major source of sport hunting activity in North America and elsewhere. In many parts of the world, rabbits have been deliberately released to create a source of meat and fibre, often to the detriment of the ecosystem. Rabbits may also serve as important hosts for potential pathogens of humans, including tularaemia and West Nile virus (Tiawsirisup et al. Reference Tiawsirisup, Platt, Tucker and Rowley2005).

There is an exhaustive published literature on the ecology, growth, reproduction, and behaviour of rabbits; however, there is relatively little published information on the ectoparasites of rabbits, especially in Canada (Kohls Reference Kohls1940; Holland Reference Holland1985). As part of a survey of ectoparasites conducted in Manitoba, I had the opportunity to include three species of Lagomorpha in the study, with the primary objective of characterising the species of ectoparasites and their infestation parameters on Lagomorpha (given that two species are hares) in the province. There are no previously published accounts of ectoparasites on rabbits in Manitoba. During the course of the study, I discovered that the eastern cottontail, Sylvilagus floridanus (Allen), was infested with the sucking louse, Haemodipsus setoni Ewing, which is a new host record for this parasite. Because most animals were salvaged from a local wildlife rehabilitation hospital, we received large numbers of juvenile cottontails. It then became apparent that there was a distinct bias in the population structure of H. setoni on adult versus juvenile cottontails, and a secondary objective became to examine the hypothesis that dispersal of lice from adult to juvenile cottontails occurred primarily in the adult stage of the louse.

Materials and methods

Collections of ectoparasites are here reported from three species of Lagomorpha: Leporidae – eastern cottontail (S. floridanus), snowshoe hare (Lepus americanus Erxleben), and white-tailed jackrabbit (Lepus townsendii Bachman), in Manitoba. For convenience, all are referred to collectively as rabbits. Most rabbits were euthanised at the hospital of the Manitoba Wildlife Rehabilitation Organization (MWRO; now Wildlife Haven, Iles des Chênes, Manitoba, Canada) at the Glenlea Research Station (Faculty of Agricultural and Food Sciences). Small numbers of animals were provided by hunters. All rabbits were salvaged under scientific collecting permits issued by Manitoba Conservation from 1994 to 2008. No attempt was made to sex or age immature rabbits; adults were sexed on the basis of external characters. For animals examined from 2005 onwards, body weights were recorded to the nearest 0.1 g; animals up to 400 g were considered to be juveniles. Each rabbit was individually bagged immediately after death and frozen for a minimum of 48 hours to kill all ectoparasites. Rabbits were allowed to thaw slightly at room temperature then were washed in warm, soapy water and ectoparasites were collected using methods described in Mironov and Galloway (Reference Mironov and Galloway2002). The body (including inside the ears) of each host was then examined for attached ticks, which were removed with forceps. Ectoparasites were preserved in 70% ethanol, and slides of representative specimens prepared (Richards Reference Richards1964). Primary infestation parameters reported here are prevalence (percentage of hosts infested) and mean intensity (mean number of lice per infested host) (Bush et al. Reference Bush, Lafferty, Lotz and Shostak1997). Most calculations and comparisons of infestation parameters were conducted using Quantitative Parasitology 3.0, as described by Rózsa et al. (Reference Rózsa, Reiczigel and Majoros2000); k was calculated for datasets that included the most heavily infested eastern cottontail using GenStat (10.2).

Although animals were examined for larval infestation by Cuterebra Clark species (Diptera: Oestridae), none were found.

Voucher specimens of arthropods are deposited in the J.B. Wallis Museum of Entomology (Department of Entomology, University of Manitoba, Winnipeg, Manitoba, Canada), the Canadian National Collection of Insects, Arachnids and Nematodes (ECORC, Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada), and the Institute of Arthropodology and Parasitology, Georgia Southern University, Statesboro, Georgia, United States of America.

Results

Eastern cottontail, S. floridanus

From 1994 to 2008, 253 cottontails were examined (58 adults and 195 juveniles), 218 of which (86.2%) came from Winnipeg, 20 (7.9%) came from various locations in southern Manitoba, and 15 (5.9%) from unrecorded locations in Manitoba. Adults were examined from 1998 to 2008 only, in every month of the year, with one (February) to seven (March and August) individuals per month. Of adults sexed, 32 were females, 11 were males. Body weights ranged from 426.2 to 1905.1 g among adults that were weighed (n = 52). Juveniles were examined from 1994 to 2008, during the breeding season, for which monthly totals for all years were: April – 5, May – 43, June – 45, July – 59, August – 17, September – 22, and October – 4. These totals include juveniles at an age prior to leaving the nest, which were often brought to the hospital by well-meaning members of the public. In some cases, the eyes and ears were not yet open, and the hair cover was very short. Body weights among all weighed juveniles ranged from 27.6 to 392.4 g (n = 150).

The only permanent ectoparasite found on the eastern cottontail was the sucking louse, H. setoni. This is the first published record for this louse infesting eastern cottontail in North America. Infestation parameters are presented in Table 1.

Table 1

Infestation parameters for the sucking louse, Haemodipsus setoni, and comparisons of infestation parameters between adult and juvenile eastern cottontails, Sylvilagus floridanus, in Manitoba, 1994–2008.

*Significantly different; χ 2 = 20.4, df = 1, P < 0.001.

**Significantly different; bootstrap two-sample t-test, t = 1.22, P = 0.395.

†95% confidence limits.

‡95% bootstrap confidence limits.

§Upper confidence limits could not be calculated with certainty.

A total of 209 324 specimens of H. setoni were collected from cottontails, 17 543 males, 37 798 females, and 153 983 nymphs; 208 842 lice (99.8%) were removed from adult rabbits, which represented 22.4% of the rabbits examined. Among the lice collected from adult rabbits, 37 483 were female and 17 432 were male (female/male = 2.15); 153 927 (73.4%) of the total lice collected were juveniles (4.11 nymphs per female). Only 482 H. setoni (0.2% of the total number of lice collected) were collected from 195 juvenile cottontails (77.6% of the total animals). Among these lice, 315 were female and 111 were male (female/male = 2.84); there were only 56 juveniles (11.6%) (0.18 nymphs per female). Of 68 infested juveniles, 41 (60.3%) were infested with adult lice only. One of these animals was the most heavily infested juvenile examined, with 24 males and 63 females; there were no nymphs on this animal. Six juvenile cottontails (8.8%) were infested with only nymphs of H. setoni, five of which had only one nymph each, and one had two nymphs. Juvenile rabbits of all apparent ages were infested with lice. The smallest infested juvenile weighed only 28.9 g and was infested with five female lice. The most heavily infested juvenile (24 male, 63 female lice) weighed 47.0 g. There was no significant correlation between juvenile body weight and numbers of lice among infested juveniles (P = 0.439). Louse infestations in adult and juvenile cottontails were highly aggregated based on calculated values of k (Table 1).

Seventeen cottontails (6.7%) were infested with the rabbit tick, Haemaphysalis leporispalustris (Packard). Animals from Winnipeg (n = 15) each were infested with one larva (n = 2), one nymph (n = 5), one male (n = 3), one female (n = 3), two larvae (n = 1), or one female and one nymph (n = 1). One animal from St. Laurent was infested with one male, and one from Springstein was infested with one nymph. No cottontails were infested with rabbit fleas, but three animals were infested with tree squirrel fleas; one animal from Winnipeg was infested with one male and one female of Monopsyllus vison (Baker), two animals were each infested with one Orchopeas caedens (Jordan). One animal was infested with one male and one female of a mouse flea, Aetheca wagneri (Baker).

Snowshoe hare, L. americanus

Twenty-four snowshoe hares were examined in this study, all of which were obtained from the Wildlife Haven. All were juveniles, with the exception of one adult (not sexed). Hares were mostly from Winnipeg (n = 18), with one each from Whiteshell Provincial Park, Hadashville, Lorette, Otterburne, Niverville, and Oak Bluff. One juvenile (4.2%) from Winnipeg was infested with five specimens (two males, three females) of H. setoni. The adult hare from the Whiteshell was infested with one H. leporispalustris larva, and one juvenile each from Lorette and Winnipeg was infested with two nymphs and one larva of H. leporispalustris, respectively. No fleas were collected.

White-tailed jackrabbit, L. townsendii

Eight white-tailed jackrabbits were examined in this study. Two adults (not sexed) were obtained from the Wildlife Haven, both from Winnipeg, each with one larva and one male of H. leporispalustris, respectively; two adult female jackrabbits from Winnipeg via the Wildlife Haven were uninfested. Three adult females and one adult male were obtained from a hunter from Morris, one female of which was infested with one male flea, Pulex irritans Linnaeus.

Discussion

There have been many investigations into the ectoparasites of rabbits (e.g., Ecke and Yeatter Reference Ecke and Yeatter1956; Stannard and Pietsch Reference Stannard and Pietsch1958; Mead-Briggs and Page Reference Mead-Briggs and Page1964; Voth and James Reference Voth and James1965; Brittain and Voth Reference Brittain and Voth1975; Harman and Chapman Reference Harman and Chapman1977; Shepherd and Edmonds Reference Shepherd and Edmonds1977; Wassel et al. Reference Wassel, Whitaker and Spicka1980; Kietzmann and Hugghins Reference Kietzmann and Hugghins1984; Pfaffenberger and Valencia Reference Pfaffenberger and Valencia1988; Clemons et al. Reference Clemons, Rickard, Keirans and Botzler2000), and in some cases, researchers have focussed specifically on lice infesting rabbits (e.g., Mead-Briggs and Hughes Reference Mead-Briggs and Hughes1965; Broekhuizen Reference Broekhuizen1971). In some studies, ectoparasites of rabbits have been reported as part of a broader survey of ectoparasites on mammals in a particular area (e.g., Beaucournu Reference Beaucournu1968; Rockett and Johnston Reference Rockett and Johnston1988; Kollars et al. Reference Kollars, Durden and Oliver1997). This is the first study of its kind reported in Canada, conducted in the northernmost extent of the range of the eastern cottontail.

Perhaps the most surprising discovery in this study was the presence of the sucking louse, H. setoni, infesting eastern cottontail. It has been recorded infesting Lepus Linnaeus species and other species of Sylvilagus Gray in North America (reviewed by Durden and Rausch Reference Durden and Rausch2007), and so its occurrence on snowshoe hare in Manitoba might be expected. The louse certainly has the potential to disperse and infest exotic hosts, as shown by its presence on native leporids in South Africa, Europe, and Asia (Durden and Musser Reference Durden and Musser1994; Dik and Uslu Reference Dik and Uslu2007), perhaps the results of introductions from North America (Durden and Rausch Reference Durden and Rausch2007). However, there have been several extensive surveys of ectoparasites on eastern cottontail in many parts of North America, without a single case of H. setoni parasitism reported. In Manitoba, the infestation among cottontails is clearly well established, with an overall prevalence of nearly 43% for the 15-year duration of the study. In some infested animals, numbers of lice were very high, with nearly 28% of adults examined infested with more than 1000 lice. One animal carried an extraordinary number of lice, 166 249. This falls short of such records noted by Murray (Reference Murray1963b, Reference Murray1965) for lice on domestic animals, but Murray's reports are for chewing lice on ungulates, much larger than rabbits or hares. To have so many blood-feeding lice on an animal the size of a rabbit likely constitutes a very high level of stress. Infestation parameters for H. setoni on cottontails in Manitoba are considerably higher than reported in other studies on other species of rabbits and hares (e.g., Brittain and Voth Reference Brittain and Voth1975; Kadulski Reference Kadulski1982; Louw et al. Reference Louw, Horak and Braack1993; Dik and Uslu Reference Dik and Uslu2008), perhaps only partly related to collection techniques.

Sucking lice live on a moving island of essential resources, their host. Being wingless, lice have limited opportunities for dispersal from one host to another, and yet must be able to do so if members of their infrapopulation are to survive beyond the life of their host. Phoresy has been suggested as a mechanism for dispersal among ischnoceran chewing lice, but has rarely been demonstrated and is improbable for sucking lice infesting small mammals (Durden Reference Durden1990). Therefore, the primary means of dispersal for H. setoni are limited to times of direct contact between hosts.

The eastern cottontail is a relatively new member of the Manitoba mammal fauna, first recorded in the Red River Valley in 1912 as it dispersed along with settlement and modification of the landscape by Europeans (Wrigley Reference Wrigley1979). Eastern cottontails gradually dispersed north and west in Manitoba, reaching at least as far north as Dauphin by the 1940s (Wrigley Reference Wrigley1979). As these colonisers moved north, they began to overlap with snowshoe hares, and are often seen in and around Winnipeg in the same fields during the day (W.O. Pruitt, Department of Biology, University of Manitoba, personal communication). It is presumably along this interface that cottontails became infested with H. setoni; by evidence presented here, the eastern cottontail is clearly an acceptable host, an essential component if a sustainable population is to arise (Clayton et al. Reference Clayton, Bush and Johnson2004). Pfaffenberger and Valencia (Reference Pfaffenberger and Valencia1988) also observed H. setoni to infest sympatric jackrabbits (Lepus californicus Gray) and cottontails (Sylvilagus audubonii (Baird)) in New Mexico, though degree of exchange of lice between these hosts is not known. Because prevalence and intensity of infestation in cottontails were very low (8.6% and 9.0%, respectively), they considered L. californicus to be the primary host and that cottontails were accidentally infested by the straggling lice on vegetation, or on visitation of jackrabbit lairs. In Manitoba, infestation in eastern cottontails is established and, it would seem, sustainable.

Contact between male and female eastern cottontail rabbits during copulation is brief, usually 10 seconds to 7 minutes (Chapman et al. Reference Chapman, Hockman and Ojeda1980); fighting is also limited because an established social hierarchy most often results in the subordinate animal backing away (Marsden and Holler Reference Marsden and Holler1964). In hosts where contact with conspecifics beyond parent and offspring is limited to reproduction and hierarchical social contact, it has even been suggested that dispersal fits the maternal transmission hypothesis (see Newson and Holmes Reference Newson and Holmes1968; Demastes et al. Reference Demastes, Hafner, Hafner and Spradling1998). Haemodipsus setoni is not a species that is congruent with this hypothesis, since it appears to shift easily to new hosts, as seems to be the case in Manitoba. However, the predominance of adult lice on juvenile cottontails is an interesting facet of dispersal in H. setoni, a clear indication of age-dependent dispersal from parent to offspring. This phenomenon has been observed in other species of Anoplura on seals (Murray and Nicholls Reference Murray and Nicholls1965; Murray et al. Reference Murray, Smith and Soucek1965; though not so clearly supported by Aznar et al. Reference Aznar, Leonardi, Vera, Vales, Ameghino, Raga and Crespo2009), sheep (Murray Reference Murray1963a), and humans (Takano-Lee et al. Reference Takano-Lee, Edman, Mullens and Clark2005). The pattern is less clear in chewing lice. Murray (Reference Murray1968) suggested that adults of the sheep biting louse, Damalinia ovis (Linnaeus), dispersed in greater numbers than nymphs. However, Lee and Clayton (Reference Lee and Clayton1995) found that on swifts, nymphs of Dennyus hirundinis (Linnaeus) dispersed in greater number from parent to offspring. The important questions here are why these patterns of dispersal prevail and what selective advantage there may be for adults or nymphs to be the predominate dispersers to a new host.

Adult H. setoni may be better able to disperse because of their size and factors related to their overall mobility. This was suggested for human head lice by Takano-Lee et al. (Reference Takano-Lee, Edman, Mullens and Clark2005). Nymphs are weakly sclerotised, are much smaller, and may disperse at greater risk than adult lice. Nymphs may simply be less active on the host, or there may even be some form of hormonal suppression of dispersal behaviour in immature forms. On the other hand, there may be advantages to adult lice dispersing to a new host. A fertilised female represents a viable, independent colonist, without a requirement for an accompanying mate. Females may also be able to lay eggs immediately upon arrival on the new host, so even if a female is unable to remain on the host for a long period; the time it would take for juvenile development, for example; its offspring may hatch and become established themselves on the host. Perhaps this favours a more rapid increase in numbers on the juvenile host at a time when it is less able to groom itself actively or before the immune system can fully respond (Colwell and Himsl-Raynor Reference Colwell and Himsl-Raynor2002), which is an important factor in establishment of a permanent infrapopulation. It is also possible that adults dispersing from a doe to its young may relieve competitive pressure for nymphs remaining on the doe by reducing stimuli for grooming by the host, or opening up available microhabitat for the nymphs. Haemodipsus setoni seems an ideal organism to test these hypotheses, especially if it can be transferred to domestic rabbits, a host that is adaptable to experimental conditions and for which there is considerable information available on its immune responses to ectoparasites.

The only previous record for a rabbit flea in Manitoba was recorded by Holland (Reference Holland1985): Euhoplopsyllus glacialis lynx (Baker), collected by Leonard Kelton from the nest of a bank swallow (Riparia riparia (Linnaeus); Aves: Hirundinidae) in the southeast corner of the province. This species typically infests snowshoe hare (Kohls Reference Kohls1940); although Holland's host record is unusual, perhaps this species infests hares in that part of the province. Cediopsylla simplex (Baker) and Odontopsyllus multispinosus (Baker) commonly infest rabbits in North America, especially eastern cottontail in other parts of its range (Stannard and Pietsch Reference Stannard and Pietsch1958). Holland (Reference Holland1985) even suggested that O. multispinosus might be found on cottontails in Manitoba, based on the proximity of available records at the time. Cediopsylla inaequalis inaequalis (Baker) and Hoplopsyllus affinis (Baker) were reported on hares in southwestern North Dakota (Voth and James Reference Voth and James1965; Larson et al. Reference Larson, McKenna and Fellows1985); the former species and C. simplex were reported by Kohls (Reference Kohls1940), Anderson and Jones (Reference Anderson and Jones1971), and Kietzmann and Hugghins (Reference Kietzmann and Hugghins1984) in South Dakota.

Rodent fleas collected from rabbits in the present study were accidental; their occurrence is not surprising given results from other studies (e.g., Haas and Dicke Reference Haas and Dicke1959). However, it is possible that these rodent fleas were acquired while rabbits were housed in the wildlife hospital. Red squirrels and grey squirrels are commonly submitted for rehabilitation, though mice and voles are rarely submitted. Similarly, it is not surprising to find P. irritans infesting rabbits. This species has been recorded from rabbits elsewhere (see Kietzmann and Hugghins Reference Kietzmann and Hugghins1984; Holland Reference Holland1985), but, in Manitoba, it is most closely associated with wild Canidae (Mammalia) based on my own observations. It is evident from this study that although rabbit hosts are present and available in Manitoba, some aspects of the environmental conditions are unsuitable for establishment of fleas typical of these hosts elsewhere in their ranges.

The rabbit tick is the most widely distributed species of tick in North America. It has been recorded from Alaska south to Argentina and it occurs in every province in Canada. In Nova Scotia, prevalence of infestation on snowshoe hares exceeded 75% and many animals were infested with more than 100 ticks at certain times of the year (Campbell et al. Reference Campbell, Ward and Garvie1980). In Minnesota, Green et al. (Reference Green, Evans and Larson1943) reported average infestations of more than 3000 ticks on snowshoe hare in late summer, with as many as 16 000 ticks found on one animal. Therefore it is surprising rabbits examined in the current study were never heavily infested and prevalence was low. Field studies on this tick should provide better information on the nature of its prevalence and intensity on rabbits in the province.

The relationship between rabbits and their ectoparasites is a dynamic one worthy of further study. In particular, the eastern cottontail dispersed into Manitoba on the coat-tails of human modifications of the landscape through settlement and agricultural practices. Along the eastern cottontail's journey north, it seems to have outdistanced contact with fleas that infested it in its source populations in the south. At the same time, there were novel encounters with snowshoe hare, which may have resulted in infestation with a new ectoparasite, the sucking louse, H. setoni. It will be fascinating to follow the development of this association. Will H. setoni be carried in the future on a new dispersal path, expanding its range south and east to other areas in the range of eastern cottontail? Will it be restricted along a broad interface of contact, where repeated colonisation from the local snowshoe hare population is possible, or will eastern cottontail become resistant to infestation and H. setoni eventually disappear from local cottontail populations, or at least decline in its infestation parameters and impact?

Acknowledgements

Thanks go to the staff at the Manitoba Wildlife Haven for their care in processing hosts for examination in this study; Lisa Tretiak in particular was hospital manager during much of the duration of this study. Dave Holder provided indispensable technical support throughout this study, and a number of additional people assisted in washing rabbits, including Lisa Babey, Chérie Dugal, Andrew Galloway, Drew Holder, and Todd Whiklo. Lance Durden, Institute of Arthropodology and Parasitology (Georgia Southern University, Statesboro, Georgia, United States of America) confirmed the identification of H. setoni. Thanks also to the continued support of staff at Manitoba Conservation who issued salvage permits for the study; J.E. Christie kindly provided specimens of white-tailed jackrabbits; Neil Holliday, Department of Entomology, University of Manitoba helped with statistical analysis using GenStat. Funding was provided, in part, by a Discovery Grant from the Natural Sciences and Engineering Council of Canada. Manitoba Conservation (SDIF) provided funding for preparing and databasing specimens.

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Figure 0

Table 1Infestation parameters for the sucking louse, Haemodipsus setoni, and comparisons of infestation parameters between adult and juvenile eastern cottontails, Sylvilagus floridanus, in Manitoba, 1994–2008.