The Gulf Coast tick, Amblyomma maculatum Koch (Acari: Ixodidae), is a unique univoltine ectoparasite of seven vertebrate host classes in the Western Hemisphere that is increasingly recognized as a pest of livestock and wildlife, a vector of pathogens to humans and canines, and a putative vector of Ehrlichia ruminantium, the causal agent of heartwater, a fatal foreign animal disease of ruminants resident in the Caribbean. This review assembles current and historical literature encompassing the biology, ecology, and zoogeography of this tick and provides new assessments of changes in cyclical population distribution, habitat associations, host utilization, seasonal phenology, and life history. These assessments are pertinent to the emergence of A. maculatum as a vector of veterinary and medical importance, and its pest management on livestock and other animals.

The physiology of ticks supports a diverse community of non-pathogenic and pathogenic organisms. This study aims to initially characterize the microbial community present within colony-reared Amblyomma americanum using PCR of the variable region 5 of the 16S rRNA gene followed by semiconductor sequencing and classification of sequence data using the Ribosomal Database Project and MG-RAST analysis tools. Comparison of amplicon library datasets revealed changes in the microbiomes in newly engorged nymphs, newly-molted adults, and aged adults, as well as ticks exposed to different environmental conditions. These preliminary data support the concept that microbe survivorship and diversity are partially dependent upon environmental variables and the sequence of blood feeding, molting, and aging. The maintenance and/or emergence of pathogens in ticks may be dependent in part on temporal changes in the microbial community of the tick microbiome.

No abstract

Off-host survival, water balance, and cold tolerance of unfed adult, Cayenne ticks, Amblyomma cajennense (F.), were examined to evaluate species characteristics important to zoogeography and off-host ecology. Survivorship decreased when males and females were subjected to progressively drier constant environmental conditions. Average maximum survival was 641.2 and 682.5 d at 85% RH and 23 degrees C (2.98 mm Hg) for males and females, respectively. Mean survival in both sexes was progressively less variable in drier conditions. Slopes of log-linear models of survival days based on saturation deficit (mm Hg) were significantly different between males and females at 50%, but not at 25 or 0%. Whole-body water loss rates for 4-wk-old adults were measured at 0% RH and 23 degrees C until ticks became nonambulatory. The mean whole-body water loss rate of females, 0.06128% h-1, was 11.3% less than for males, 0.06914% h-1. Although nonambulatory ticks appeared dead, >1/2 of the individuals from each sex regained ambulatory status after they were removed from 0% RH and exposed to 96% RH for 24 h. Among these, male ticks averaged 0.44 more recuperative (ambulatory) cycles than females, although, the duration encompassing all recuperative cycles was generally longer for females and on average, females gained 8.16% more weight than males upon each rehydration. Estimates of the mean critical equilibrium activity for males and females were 0.74 av and 0.79 av, respectively. A. cajennense adults were found to be less tolerant to -12.5 degrees C than adult lone star ticks, Amblyomma americanum (L.), whose distribution encompasses more temperate regions. Although A. cajennense exhibit little host preference and are capable of extended off-host survival, the establishment of populations beyond this species zoogeographic distribution may be constrained by an intolerance to cold.

A survey of ectoparasites from 219 meadowlarks conducted during 2 consecutive fall-winter periods in a coastal prairie found immature Amblyomma maculatum Koch to be the most abundant parasite. Peak larval infestations occurred in December with 80-100% of collected birds infested and with a monthly mean of up to 34 larvae per bird. Peak nymphal infestations occurred in February or March with 95-100% of birds infested and with a monthly mean of up to 11 nymphs per bird. Seasonal dynamics of these stages offered possible insight into the persistence of A. maculatum in an area long infested with the red imported fire ant, Solenopsis invicta Buren. Four other species of ticks also were collected but in substantially lower numbers; Amblyomma cajennense (F.), Amblyomma inornatum (Banks), Haemaphysalis chordeilus (Packard), and Haemaphysalis leporispalustris (Packard). This appears to be the 1st host record of A. cajennense from meadowlarks. A collection of 17 northern bobwhite quail indicated that most of these birds were infested with A. maculatum but at a lower level than meadowlarks. The collections of 2 species of Mallophaga from meadowlarks and 4 species from the northern bobwhite quail are discussed.