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The spirochete Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Benner is transmitted by Ixodes scapularis Say, a vector of Lyme disease. As a 1st step into investigating the possibility of biocontrol of the tick, we identified the microbiota associated with the ticks. We collected, identified, and determined the sex of ticks from foliage and deer. Seventy-three initial bacterial isolates were recovered from 43 ticks (27 adults and 16 nymphs). The bacteria isolated from nymphs were qualitatively different (mainly gram-negative cocci) from the bacteria isolated from adult ticks (gram-negative and gram-positive rods). To determine long-term viability, these isolates were stored for 6 mo under laboratory conditions. After storage, 63 surviving bacterial isolates were characterized using the Biology System of identification by substrate utilization. Forty-four isolates were identified to the species level. Our characterization efforts focused on the 40 spore-forming bacteria, which could prove useful in the biocontrol of ticks. Eleven species of Bacillus were identified. Bacillus thuringiensis-B. cereus was the predominant species group isolated. Six isolates from this group formed crystals.

As a measure of the risk for exposure to Lyme disease, we estimated the distribution of host-seeking adults of the blacklegged tick, Ixodes scapularis Say, on dairy farms in Barron County in northwestern Wisconsin. Vegetation ecotypes that were common to 18 farms that were representative of the county were surveyed by flag sampling. Tick prevalence and abundance, which were similar during fall and spring periods, were very low in farmhouse yards and forage croplands; only a single male was collected from 17 lawns. Sampling of 18 pastures with lactating cows also yielded only a single I. scapularis. In contrast, I. scapularis adults were captured in 9 of 37 samples from 18 pastures with heifers and dry cows; in those pastures, ticks were associated with woods and secondary vegetation or margins of pastures adjacent to woodlands. Blacklegged ticks were most prevalent and numerous in ungrazed woodlands; adults were captured in 27 of 53 samples on 13 of 15 farms, particularly when evidence of white-tailed deer, Odocoileus virginianus (Zimmermann), was apparent. The risk of encountering adult blacklegged ticks on dairy farms in Barron County, Wisconsin is therefore greatest in woodlands habitat. The presence of adult ticks in pastures with heifers and dry cows establishes an ecological basis for the exposure of dairy cattle to adult I. scapularis. Pastures with lactating cows, farmhouse yards, and forage croplands represent negligible risk.

The attachment site pattern of adult Ixodes scapularis Say on white-tailed deer and horses in Maryland was determined by whole-body examinations during fall and spring periods of tick host-seeking activity. On deer in the fall, both female and male I. scapularis attached largely to anterior dorsal body regions, with attachment to the ears (outside), head, neck, and brisket accounting for 87.9% of females and 86.6% of males. The attachment pattern of females differed between bucks and does during fall, but not in spring, and both females and males were more abundant on bucks than does during fall, but not in spring. Neither female nor male attachment patterns on deer differed between fall and spring seasons. In contrast to deer, the ears and neck of horses were largely devoid of blacklegged ticks, and 84% of the females were attached either on the chest, in the axillae of the fore and rear legs, or under the jawbone. The restricted attachment of female blacklegged ticks to ventral body regions of horses may reflect avoidance of light. An understanding of the attachment patterns of adult I. scapularis, an increasingly abundant and economically important species, enhances sampling of feeding ticks, deticking to limit host irritation or exposure to tick-borne pathogens, and identifies body areas that should be targeted for delivery of repellents or acaricides.

Adult blacklegged ticks, Ixodes scapularis Say, were confined to clay islands each surmounted with a vertical glass rod, and tick activities were videotaped continuously for 48 h. Some rods were treated basally or apically with substances rubbed from pelage associated with the tarsal or interdigital glands of white-tailed deer, Odocoileus virginianus (Zimmermann). Except for the activity immediately following their release, tick activity on both days was greatest during the period from 1700 to 2300 hours, which coincided with the onset of scotophase. Ticks were most active when rods had interdigital gland substances applied to their basal 2 cm, whereas they were least active when confined with rods treated with tarsal gland substances on their apical 2 cm. Overall, ticks spent more time on the apical 2 cm of the glass rods during the scotophase than during the photophase. The highest level of apical arrestment among treated and untreated rods occurred when the rod tips were treated with tarsal gland substances, with female ticks on the apical 2 cm of the rods 70-100% of every 3-h period beginning with the period from 2000 to 2300 hours on day 1. In contrast, when tarsal gland substances were applied to the basal 2 cm of the rods, the ticks spent < 40% of every period on day 2 on the rod tips.

Silt fence barriers were set along pasture fencelines and evaluated as a method of restricting the dispersal of blacklegged tick, Ixodes scapularis Say, adults and nymphs from woodlands into adjacent horse pastures. The barriers received no acaricidal treatment for the 1st cohort of adults. Thereafter the woods side of the barriers was sprayed with cyfluthrin at the onset of each season of host seeking activity of nymphs and adults. When high densities of adults were present, the barriers significantly limited the numbers of ticks in pastures. Nymphs, however, were not significantly fewer in numbers in pasture areas associated with the barriers compared with control areas. Marked adult ticks released in woodlands and ecotones were recaptured on mowed verges and pastures, but there was little dispersal from the woods edge into the woods.

Marked nymphal and adult blacklegged ticks, Ixodes scapularis Say, were released in 4 host-exclusion cages and 4 similar control areas, all straddling the woods-pasture interface. Both nymphs and adults were recaptured by flagging at regular intervals outside the cages, having therefore actively dispersed > 4.5 m (i.e., without involvement of vertebrates). Nymphs were recaptured much more often ( > 90%) in the woods than pastures, whereas 62.8% of recaptured adults were taken in pastures. Females were recaptured in equal numbers in pastures and woods, but 75.4% of recaptured males were in pastures. Adults that dispersed into pastures were recaptured an average of 1.6 and 3.7 m from the woods edge in 1992 and 1993, respectively, and as far as 7-8 m from the woods edge. Nymphs dispersed shorter distances than adults with 66% of the recaptured nymphs found 2-3 m from their release points, and > 46% of recaptured adults found > 5 m from their release points. Twice as many nymphs were recaptured from the caged than uncaged sites. The lower numbers of nymphs recaptured from control sites compared with caged sites are probably the result of host acquisition; the absence of this discrepancy with the adults may reflect by their ability to move relatively quickly from the host-exclusion cages and become available for host contact.

In a field test, adult blacklegged ticks, Ixodes scapularis Say, of both sexes exhibited an arrestant response to substances associated with external glands on the legs of white-tailed deer, Odocoileus virginianus (Zimmermann), their principal host. Substances rubbed from the pelage covering tarsal and interdigital glands were applied to artificial vantage points simulating vegetation on which I. scapularis adults wait for host contact. A combination of tarsal substances (applied to the apex of the simulated vantage point) and interdigital gland substances (applied to the horizontal base) elicited a greater response than either treatment alone. A minimal response was observed on untreated vantage points. In laboratory bioassays using glass tubing as vantage points, substances associated with preorbital glands of deer elicited a strong arrestant response among I. scapularis females, whereas samples rubbed from the forehead, back, and a nonglandular area on deer tarsi evoked weak arrestant responses. These results support the hypothesis that the kairomonal properties of host-generated residues, either in conjunction with or in lieu of the effects of carbon dioxide, help account for the prevalence of host-seeking ticks along animal trails.