IXODES-SCAPULARIS (ACARI, IXODIDAE) DEER TICK MESOSCALE POPULATIONS IN NATURAL AREAS - EFFECTS OF DEER, AREA, AND LOCATION

Nymphal Ixodes scapularis Say deer ticks were collected at 22 parks or other natural areas on Long Island, New York, to examine the relation ship between tick populations and geographic position, size of area, p resence of white-tailed deer, Odocoileus virginianus (Zimmerman), and numbers of human Lyme disease cases in adjacent communities. Nymphal t icks were 93% less abundant when deer were absent and were also less c ommon in smaller natural areas. Geographic position on Long Island was not important. Tick numbers were significantly correlated with human Lyme disease incidence in adjacent townships. A second survey of larva l ticks from five areas where deer were absent and six where deer were present found larvae present at four of the five sites without deer, but at only 2% of the levels found where deer were present. These resu lts suggest that populations of I. scapularis can occur and reproduce in the absence of white-tailed deer, so that eradication of all deer w ould greatly reduce, but not eliminate, all risk of Lyme disease.