Host-dependent differences in feeding and reproduction of Ixodes dammini (Acari: Ixodidae).

The frequencies with which adult Ixodes dammini Spielman, Clifford, Piesman and Corwin feed upon white-tailed deer (Odocoileus virginianus), raccoons (Procyon lotor), opossums (Didelphis virginiana), and domestic cats were compared in a wooded site in northeastern United States. By combining estimates of the quantity of ticks feeding on each host species with host densities, we derived the relative contribution made by each kind of host to the feeding of the tick population. To compare engorgement success and reproductive efficacy, we weighed ticks found on these hosts and compared tick weights with the quantity of eggs produced. Deer harbored the most female ticks per individual and, although deer were less abundant than raccoons, they harbored 94.6% of the feeding tick population. Raccoons, cats, and opossums, respectively, provided blood meals to 3.6, 1.6, and 0.2% of feeding adult ticks. Ticks engorged more successfully on cats and raccoons than on deer, and egg production correlated linearly with weight of female ticks collected from both cats and deer. Although these ticks engorged better on other hosts, the vast majority of eggs resulted from ticks that had fed on deer. We conclude that, in this site, the abundance of deer largely determines the abundance of I. dammini, the vector of the agent of Lyme disease.

Microgeographic distribution of immature Ixodes dammini ticks correlated with that of deer.

In order to determine whether the small-scale distribution of immature Ixodes dammini Spielman et al. corresponds closely to the activity patterns of white-tailed deer, Odocoileus virginianus (Zimmerman), these relationships were examined in a site on Long Island, New York, U.S.A. We first determined the extent and temporal pattern of adult ticks feeding on deer by examining twenty-three resident deer tranquilized during September-December 1985. I. dammini adults infested deer throughout this fall period, most abundantly during October and November. With radio-telemetry collars attached to deer we determined the relative frequency that they occupied 0.25 ha quadrats of the study site. During the following summer, we examined white-footed mice, Peromyscus leucopus (Rafinesque), that inhabited these quadrats and removed immature ticks from each. 8975 larval and 163 nymphal I. dammini were removed from 208 mice trapped in forty-three such quadrats. The frequency of deer using these quadrats was positively correlated with both the number of larval and of nymphal ticks per mouse. These results suggest that risk of I. damminiborne zoonotic disease may be decreased by locally reducing deer density in sites that experience intense human activity.