Effects of Infection byArsenophonusandRickettsiaBacteria on the Locomotive Ability of the TicksAmblyomma americanum,Dermacentor variabilis, andIxodes scapularis

Abstract

The goal of this study was to determine the effect of vertically transmitted Arsenophonus and Rickettsia bacteria on locomotive ability of larvae of three eastern North American tick species: Amblyomma americanum, Dermacentor variabilis, and Ixodes scapularis. We conducted two different experiments on flat or inclined surfaces to measure tick motility. In each experiment, a moderately heated surface was used and placed at a selected incline. The individual's path across the surface was traced for a period of 2 min, or until the larval tick had moved off the surface. Following the microbial identification of Arsenophonus and Rickettsia, a mixed model analysis of variance (ANOVA) indicated that clutch microbial infection status had a significant effect on tick motility with Rickettsia increasing and Arsenophonus decreasing motility averaged over tick species and inclines. There was also a significant difference in motility among tick species and a highly significant effect of the Species*Incline interaction where Dermacentor had higher motility than Ixodes on the flat surface.

Seasonally biased or single-habitat sampling is not informative on the real prevalence of Dermacentor reticulatus-borne rickettsiae — A pilot study

“…Relevant to the present results, it was demonstrated that rickettsiae induced higher motility among Dermacentor sp. ticks (Kagemann and Clay, 2013), which (theoretically) may cause earlier questing of rickettsia-infected ticks.…”

Characterization of the Bacterial Communities of Life Stages of Free Living Lone Star Ticks (Amblyomma americanum)

“…If Coxiella is obligate for the survival of A. americanum [21], the number of bacteria may increase in females to ensure 100% transmission to eggs. An alternative, but not mutually exclusive, explanation is that males may contain higher numbers of R. amblyommii to facilitate increased locomotion [68], which would increase reproductive fitness if it enabled more mating opportunities for males. The distribution of nymphal bacterial communities across the gradient from Rickettsia dominated to Coxiella dominated suggests that sex-biased bacterial communities may arise in unfed questing nymphs (Figure 4).…”

Ixodes pacificus Ticks Maintain Embryogenesis and Egg Hatching after Antibiotic Treatment of Rickettsia Endosymbiont

“…For example, Rickettsia phylotype G021 might be a beneficial symbiont of larval, nymphal, and flat adult stages of I. pacificus in the environment by enhancing the host’s general fitness, possibly by protecting the host against stress factors that do not affect the tick in the lab. Rickettsia ’s likely role in increasing larval motility of ticks I. scapularis , A. americanum, and Dermacentor andersonii, provides an example of a potential fitness benefit [16]. Concerning protection from environmental stress, Rickettsia is associated with heat-induced upregulation of structural proteins in the whitefly B. tabaci [48].…”

“…In addition to overall fitness, these experiments can shed more light on the intriguing possibilities for Rickettsia ’s specific function in the tick, such as increased motility [16]. Rickettsia has been found in I. pacificus ’ relatives, I. scapularis [18] and I. ricinus [17], but almost nothing is known about those Rickettsia -tick relationships.…”

“…Reproductive manipulation is a possibility as endosymbiotic R. bellii universally infects a strictly parthenogenetic tick species, Amblyomma rotundum [15]. However, Rickettsia has been implicated in increased larval motility of the ticks Ixodes scapularis , Amblyomma americanum, and D. andersoni, likely making it easier for the tick species to access hosts [16].…”