Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 17, 1997
Publication Date: N/A
Interpretive Summary: Blacklegged ticks are the principal vectors of the pathogens causing Lyme disease and human granulocytic ehrlichiosis (HGE) in the eastern and central U.S. Finding suitable hosts is critical for tick survival and reproduction. Substances associated with external glands on the legs of white-tailed deer aid adult blacklegged ticks in finding sites where they wait for hosts. In order to elucidate the behavioral responses of blacklegged ticks to 2 deer leg gland substances (1 believed to arrest wandering and the other to influence climbing), ticks were videotaped continuously for 48 h on glass rods treated with these substances. The vertical glass rods simulated the vegetation on which ticks wait for hosts. Ticks were more active during the night. In the presence of tarsal gland substances ticks spent considerable periods of time immobile at the rod tips, whereas in the presence of interdigital gland substances, ticks were more active than ticks on untreated rods. These results are of interest to researchers studying the host-finding behavior of ticks, and they may lead to the development of new technologies and strategies for keeping ticks from areas frequented by humans and domesticated animals.
Technical Abstract: Adult blacklegged ticks, Ixodes scapularis Say, were confined to clay islands each surmounted with a vertical glass rod, and the ticks' activities videotaped continuously for 48 h. Some rods were treated in prescribed areas with substances rubbed from pelage associated with the tarsal or interdigital glands of white-tailed deer, Odocoileus virginianus (Zimmermann). Ticks of both sexes exhibited the highest level of locomotory activity during the first 3 h after their release on the islands. Many ticks resumed activity during the period from 1700 to 2300 h, which coincided with the onset of scotophase. Activity was minimal until the next 1700 to 2300 h period. Ticks released on islands with rods that had interdigital gland substances applied to the basal 2 cm of the rods were most active, whereas ticks confined with rods treated with tarsal gland substances on their apical 2 cm were the least active. Overall, ticks spent more time on the apical 2 cm of the glass rods during the scotophase than during the photophase. When the rod tips were treated with tarsal gland substances, female ticks were on the apical 2 cm of the rods 70 - 100% of every 3-h period beginning with the 2000 to 2300 h period of day 1, whereas ticks on untreated rods and on rods treated with interdigital gland substances spent significantly less time on the rod tips. These results are consistent with the scenario that deer leg gland substances act as kairomones with tarsal gland substances eliciting arrestant behavior in adult I. scapularis and interdigital gland substances influencing tick climbing behavior.