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Geology topics

J. F. Carroll

Publications and source records attributed to J. F. Carroll.

2 recordsLinked to original sources

Population dynamics of American dog ticks (Acari: Ixodidae) along park trails

We conducted a mark–recapture study in which drag-collected ticks were removed from some park trails weekly from April to July. Weekly survival rates (probability of surviving and remaining on the trails) were significantly lower on trails used heavily by hikers, horses, and pets than on trails used less frequently. Although usage was the only obvious difference among these trails, differences in weekly survival rate estimates may be attributable to differential success in acquiring hosts. The estimated probability of capturing a host-seeking tick located along a trail on a single drag was 0.20 on the drag alone, and 0.25 including the person dragging. When routes parallel to the trails and of equal lengths were dragged immediately after sampling the trails, only ≍5% as many ticks (including ticks on the person dragging) were found off the trails as on them. We found no evidence of reduced tick numbers on removal trails, but this result should be considered inconclusive because the power of the discerning test was low. However, the data reported here provide insights into turnover rates of the adult Dermacentor variabilis population and effectiveness of the drag as a sampling device.

Environmental Entomology

Parasitization of meadow voles, Microtus pennsylvanicus (ORD), by American dog ticks, Dermacentor variabilis (Say), and adult tick movement during high host density

The numbers of host-seeking adult American dog ticks, Dermacentor variabilis (Say), in a sweet gum field in Maryland reflected changes in the population density of a host species, the meadow vole, Microtus pennsylvanicus (Ord), which within 1.5 yr fell from an estimated 157 to 8 voles on a 0.8 ha grid. During high vole density, there was no significant difference ( P > 0.05) in tick burdens between sexes on an annual basis. Juvenile and subadult voles (< 33 g) harbored significantly fewer D. variabilis larvae and nymphs than did mature voles (> 33 g) on an annual basis. However, during periods of both peak host-seeking activity by D. variabilis larvae and nymphs and high host density nearly all the voles examined were infested. There was no evidence of a relationship between weight of adult voles and likelihood of parasitization by D. variabilis during months of moderate tick host-seeking activity. Of 163 adult D. variabilis recaptured ≥ one week after marking, 86 (52.7%) had moved > 3.8 m, 59 (36.2%) > 5.3 m.

Journal of Entomological Science