Ticks Getting to Know Your Ticks

TICKS GETTING TO KNOW YOUR TICKS TERRY D. GALLOWAY, Department of Entomology, Faculty of Agricultural and Food Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2. Terry [email protected] Figure 1. Male (left) and female (right) American dog ticks, Dermacentor variabilis. Note the distinct white markings on the scutum of each specimen. Terry Galloway When I moved to Manitoba in 1973, Since then, I have had many opportunities everybody warned me about the cold winters to study ticks in Manitoba and to talk to and the hot summers. Many people warned people about ticks and tick lore. My first me about the abundance of ferocious research experience was in 1979 and 1980, mosquitoes. Not one person, though, said with a graduate student who was particularly anything about the wood ticks! Not one. interested in the juvenile stages of the wood My first encounter with ticks was on a trip tick or American dog tick, Dermacentor to the field to collect mosquito larvae in May. variabilis (Say) (Burachynsky 1982; I was rather amazed when we were returning Burachynsky and Galloway 1985). Since to our truck and my companions started that time, I have been involved with various stripping down and removing ticks. I had tick survey activities in Manitoba, notably only ever seen one tick, on a cat, in my 23 the surveys to determine the distribution and years in southern Ontario, and that was abundance of the blacklegged tick or deer considered an extreme rarity at the time. But tick, Ixodes scapularis Say, in Manitoba and here we were just outside of Winnipeg, Saskatchewan. In this article, I briefly removing dozens of ticks from our own describe many species of ticks on the bodies. What kind of place was this? prairies, and discuss the life cycles of some 60 (2). June 2002 107 of the more commonly encountered species. The American dog tick, D. variabilis, can Ticks are amazing animals, and I hope I can be extremely abundant throughout southern convince you to look at them in a slightly Manitoba and southeastern Saskatchewan. different light after you have read this There is evidence that this tick has gradually account. been increasing its range north and west in recent years. The adults are active from the Ticks on the Prairies time the snow disappears right through to There are 34 species of ticks recorded in early August, though the main peak in Canada (Wilkinson 1979; Lindquist et al. abundance is in May and June. Under 1999), of which at least 11 are known for favourable weather conditions, the adults the prairie region. There are other species, rest in the grass and low shrubs waiting for perhaps an additional four or five, that are a passing host, their front legs poised to latch currently unknown, but which may onto hair or fabric. They do not jump, and eventually be discovered in Canada, and they generally stay in low vegetation, not there are many others which we see mainly venturing into the overhead branches of as accidental introductions on birds, pets, trees. They will attach to a wide variety of domestic animals or humans, which are host species, including foxes, coyotes, unlikely to become established here. For wolves, dogs, skunks, porcupines, racoons, some insight into the potential for cats, bears, badgers, deer, cattle, horses and importation of exotic ticks, refer to Keirans humans. Females require several days to and Durden (2001), who reported 99 species engorge fully with blood. At this time, males imported into the United States. The on the host seek out feeding females and following is an account of some of the more mate with them. If you flip up a feeding frequently encountered hard ticks in the female to expose her underside, you will Canadian Prairies. There are species of soft often find a male or group of males. When ticks, also called argasid ticks, which are a female has taken all the blood it can, it parasites of birds, bats and some rodents, drops to the ground and seeks a sheltered but these are generally not common on the spot to lay its eggs, of which there may be prairies and will not be considered here. 1000-7000, laid over about three to six weeks.3 After all the eggs are laid, the female Dermacentor spp. dies. Six-legged larvae hatch from the eggs This genus includes three of the most and remain dormant in dense clusters in the conspicuous of all the ticks: D. variabilis leaf litter, where they will spend their first (the wood tick, or American dog tick), D. winter. In the spring, they crawl a short andersoni Stiles (the Rocky Mountain wood distance onto the surrounding vegetation, tick), and D. albipictus (Packard) (the winter and attach to small rodents, especially voles, tick or moose tick). Paul Wilkinson has deer mice, jumping mice and chipmunks. provided the most extensive discussion of When they are engorged with blood, they these ticks in Canada.13 The adults of all three drop to the ground and moult to eight-legged species are generally dark, reddish brown, nymphs. These nymphs actively seek a host and beautifully ornamented with white during July and August, including the same streaks and spots on their backs. Females, species used by the larvae, to which they as in all species of hard ticks, have a plate¬ attach and feed to engorgement before like scutum that only partially covers the dropping to the ground, where they moult anterior region of the back, while the scutum to eight-legged adults. Most of these adults in males extends all the way across the back. become dormant and spend the winter in the It is the scutum that bears the white leaf litter, before becoming active in the markings, so it is easy to recognize at a spring and seeking their hosts. Just think, glance whether you have found a male or the majority of the adult wood ticks that we female (Figure 1). see in the spring would have begun their I OS Blue Jay lives at least two years earlier. It is likely may be restricted. They may even be that these adults must find a host on which responsible for the death of their host. to feed, or they will die without surviving another winter. Haemaphysalis spp. There are two species of Haemaphysalis The Rocky Mountain wood tick, D. that may be encountered in the Prairie andersoni, is found in western Canada, region. Haemaphysalis leporis-palustris throughout south-central British (Packard) is very common and abundant on Columbia, southern Alberta and east into rabbits and hares, especially in the ears. This southwestern Saskatchewan. The life small tick rarely attacks humans or domestic cycle of this species is very similar to that animals, but the juvenile stages may be of the American dog tick, except that the occasionally found on birds. Haemaphysalis timing of the various stages is slightly chordeilis (Packard) is a parasite of grouse, different. When the larvae hatch from the especially Sharp-tailed Grouse in parklands, eggs, they don’t become dormant, but and seems to be relatively host specific. immediately begin to search for suitable Despite their host specificity, they require hosts. Once they have acquired a blood- three different hosts to complete their life meal, they drop to the ground and moult cycle. to the next stage, but in this case, it is the nymphs that become dormant and spend Ixodes spp. the winter. The nymphs become active in Ixodes is the genus with the greatest the following spring, and once fed, moult diversity of species in Canada, with at least to adults. These adults become dormant seven possible species endemic to the and spend the winter in the litter on the Prairies. Fortunately, most parasitize only a ground. The adults become active early small number of host species, and very in the spring, feed on medium-sized to seldom come into contact with humans or large hosts, including people. their pets. For example, Ixodes angustus Neumann and Ixodes muris Bishopp and The winter tick, D. albipictus, displays a Smith are mainly parasites of mice and voles, completely different life cycle from its close Ixodes sculptus Neumann and Ixodes kingi relatives. The larvae become active in Bishopp mainly attack ground squirrels, September and form dense aggregations on Ixodes cookei Packard is usually found on the vegetation, especially in areas where woodchucks, and Ixodes banksi Bishopp moose are abundant. Although they are most typically parasitizes beavers. often associated with moose, they will also attach to deer, elk, cattle and horses. There is one vagrant species of Ixodes that Humans, too, are sometimes infested, and I occurs in the Prairie Provinces, the have dealt with calls from many anxious blacklegged tick or deer tick, Ixodes people who have found themselves covered scapularis Say. Although this species has by hundreds of tiny larval ticks. As the gained notoriety due to its role as vector of season advances, the larvae feed and moult the pathogen that causes Lyme Disease to eight-legged nymphs, while still on the throughout much of eastern North America, same host. After the nymphs have fed, there is no conclusive evidence that /. usually from October to mid-February, they scapularis has become established and moult to the adult stage, but again remain actually breeds in any of the Prairie on the same host animal.4 This tick can infest Provinces. However, they are readily moose at extraordinary levels, frequently in transported great distances by migrating the tens of thousands," and have tremendous birds, and since these vagrant ticks may have impact on the health and well-being of the become infected with pathogens in their animal, especially where the range of moose endemic homes, they have the potential to 60 (2).

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