Microclimate and Habitat in Relation toIxodes scapularis(Acari: Ixodidae) Populations on Long Point, Ontario, Canada

Abstract

The impact of microclimate and density of hosts for adult ticks on the density of Ixodes scapularis Say was evaluated within 4 habitats on Long Point, Ontario, from 1989-1992. During the period from May to September, mean weekly vapor pressure deficits were greater within the oak savannah and cottonwood dune habitats than at the maple forest and white pine habitats, which were similar. Vapor pressure deficit was likely the major factor affecting the survivorship of eggs and immature tricks in these habitats. Based on drag sampling, I. scapularis adults demonstrated peak activity in April and October of each year. The mean number of I. scapularis adults collected by dragging during the fall or in the spring did not differ significantly within each habitat. The mean number of adults collected also did not differ among tick cohorts within each habitat; however, significantly more adults were collected within the maple forest than in the white pine habitat. The mean number of I. scapularis adults per white-tailed deer, Odocoileus virginianus (Zimmerman), increased from 1989 to 1991 and then decreased in 1992. Significantly more adult I. scapularis infested deer were observed in 1990 than in 1989. Removal of deer in 1989 and 1990 resulted in a calculated decrease of > 100,000 fed female ticks. Although seasonal variation in microclimate within habitats was closely linked with tick survival and partly explains the differences in abundance of I. scapularis among habitats on Long Point, habitat utilization by deer was also a primary factor governing the local abundance of I. scapularis populations.

The Biological Survey of Canada: A Personal History

“…Unlike the other human-biting ticks in Canada, unfed adults of I. scapularis begin active host-seeking in fall rather than spring. Adults first appear in late September and are most active in October and April though they can be collected as late as mid-December and from mid-March to July (Lindsay et al 1999a). Adults seeking hosts in the fall and subsequent spring represent the same cohort of ticks.…”

“…Adults (and nymphs) are frequently collected in deciduous or coniferous woodlands and from ecotonal (i.e., unmaintained edge) habitats (Maupin et al 1991), though these instars are also collected on lawns and ornamental shrubbery in suburban residential areas (Stafford and Magnarelli 1993). The abundance of adult blacklegged ticks varies among habitats (Guerra et al 2002;Brownstein et al 2005) and from year to year (Lindsay et al 1999a(Lindsay et al , 1999b. Female adult blacklegged ticks require 6-10 days to feed to repletion (Troughton and Levin 2007).…”

“…The prevalence and abundance of larvae decrease in July and then usually increase again in August when the larvae of that year hatch (Lindsay et al 1999b). Larval ticks are most abundant in wooded habitats (Maupin et al 1991;Lindsay et al 1999a) and survival is predicted to occur at more northerly latitudes in the face of climatic change Ogden et al 2006a). Larvae feed for up to seven days, but most drop from their hosts on the fourth day (Troughton and Levin 2007).…”

Climatic analysis of Lyme disease in the United States

“…Previous work has also highlighted the microclimate of the vector's habitat (i.e. leaf litter; Dennis et al 1998, Lindsay et al 1999; therefore, future researchers may wish to further investigate the microscale climate of the tick's habitat (i.e. ground temperature, leaf litter moisture) and/or the microscale climate of the host's habitat.…”

“…deer) are abundant, although they can be found in coniferous forest as long as the leaf litter is sufficient and the climate is moist . The density and distribution of leaf litter in the tick's habitat is an important factor in its survival since it supplies the tick with a more humid resting place during dryer, hotter periods (Lindsay et al 1999). Consequently, removal of the leaf litter found in the tick's habitat has been found to significantly reduce the population of the active nymphal blacklegged tick in March and June by 72.7 to 100% (Schulze et al 1995).…”