Off‐host aggregation in the non‐fed, female brown dog tick, Rhipicephalus sanguineus (Latreille), is induced by tick excreta and enhanced by low relative humidity

Abstract

We report that Rhipicephalus sanguineus (Ixodida: Ixodidae) faeces and its main component, guanine, act as assembly pheromones in short-range Petri plate bioassays. Arrestment activity in response to guanine was lower than that in response to natural excreta, indicating the presence of other active ingredients in natural excreta. The selective removal of appendages was used to establish the important roles played by the palps and the front pair of legs in the detection of the pheromone. Reaction to chemically pure guanine at varying concentrations occurred without a dose response; thus only the presence of guanine, not a critical amount, is required to induce assembly. Higher speed and intensity of clustering occurred at 33% relative humidity (RH). We conclude that female adults of R. sanguineus are more prone to assemble under dry conditions that match the arid microhabitats preferred by this species and that this tendency allows this tick to reside in human dwellings and dog kennels that maintain standards of comfort at 30-50% RH. Cleaning or removing tick excreta-covered surfaces on which ticks aggregate from within and around human dwellings may prove useful as a means of interfering with the establishment of off-host clusters of R. sanguineus.

Conspecific hyperparasitism: An alternative route for Borrelia hermsii transmission by the tick Ornithodoros hermsi

“…Ticks would need to aggregate in or near the nest of a vertebrate host for hyperparasitism to occur. Both hard and soft ticks have a well-documented propensity to do this, which is driven by the production and sensing of pheromones (Leahy et al, 1973; Leahy et al, 1975; Leahy, 1979; Allan and Sonenshine, 2002; Yoder et al, 2013), with individuals of multiple tick species attracting other ticks up to a meter or more away (Sonenshine, 2006). Unfed ticks show a greater tendency to aggregate than fed ticks, suggesting aggregation pheromones assist in finding food (Leahy, 1979).…”

Auto‐dissemination of commercially available fungal pathogens in a laboratory assay for management of the brown dog tick Rhipicephalus sanguineus

“…Although little is known about the off‐host behavior of most tick species in their natural environment, brown dog ticks are reported to aggregate in confined spaces near the host (Dantas‐Torres, ; Yoder et al ., ). It is possible that the efficacy of pathogenic fungi could be enhanced through auto‐dissemination between aggregating conspecifics.…”