Population Structure and Seasonal Intra-Burrow Movement of Ornithodoros turicata (Acari: Argasidae) in Gopher Tortoise Burrows

Abstract

Burrows of the gopher tortoise, Gopherus polyphemus Daudin, were sampled for Ornithodoros turicata (Dugès) infestation using carbon dioxide baits and vacuum extraction. Ticks were captured, marked, released, and recaptured, and population estimates were made using the Lincoln index. Estimated population ranged from 47 to 1,338 ticks per burrow. The tick population consisted predominantly of nymphs, with a significant increase in the larval population during the months of June and July. Adult sex ratio was slightly male-biased, but numbers of adults collected were consistently low. Ticks exhibited a low interburrow movement, but depth preferences fluctuated with season; more ticks occurred in the upper strata of the burrows during the hot, humid months.

Phylogenetic Analysis of the SpirochetesBorrelia parkeriandBorrelia turicataeand the Potential for Tick-Borne Relapsing Fever in Florida

“…The animals involved in the maintenance of this spirochete in nature are not known, although laboratory mice and guinea pigs are susceptible to infection and produce microscopically detectable spirochetemias and pathological abnormalities including myocarditis, dermatitis, and lymphoid hyperplasia (12). We suspect the tick vector in Florida is O. turicata, which has been collected from locations near the infected dogs and several other counties in this state (1,25). Additional field and laboratory work is needed to determine the distribution of these ticks, the presence and prevalence of spirochetes in them, and other animals involved in the enzootic cycle.…”

Biological and ecological characteristics of soft ticks (Ixodida: Argasidae) and their impact for predicting tick and associated disease distribution

“…Table II gives an example of optimal and critical climatic conditions defined for several Ornithodoros tick species using these bibliographic resources. As for presence data, information is mainly lacking for American species, with the exception of studies published by Butler (1984), Beck et al (1986), Adeyeye & Butler (1989), and for O. turicata.…”

Reproductive bionomics of the soft tick, Ornithodoros turicata (Acari: Argasidae)

“…Such seasonal changes in the population structure suggest that the mating behaviour, oviposition and/or viability of O. turicata may be influenced by temperature and RH. This likelihood is further supported by the observation that the intra-burrow movement of O. turicata is correlated with seasonal changes in the temperature and RH (Adeyeye and Butler, 1989). In north-central Florida, most ticks inhabit the upper strata of burrows during the warm, humid months.…”

“…Ticks were assigned randomly to one of four temperatures (22,24,27 or 30°C) and one of two RHs (90 or 95%). This range of temperatures and RH was derived from general burrow conditions (Adeyeye and Butler, 1989) and specific late spring-summer data obtained from seven gopher tortoise burrows by Butler et aL (1984). Vials containing ticks were kept in 250 mm diameter humidity chambers in which the desired RH was maintained using saturated salt solutions (Winston and Bates, 1960).…”

“…For example, in north-central Florida, the burrows of the gopher tortoise, Gopherus polyphemus Daudin, are the principal habitats of the argasid tick, Ornithodoros turicata (Duges) (Beck et al, 1986). The RH of these burrows is consistently above 75% even when the ambient RH is below 50% (Adeyeye and Butler, 1989). Further, seasonal changes occur in the population structure of O. turicata.…”