Physiological Age of Field-collected Female Taiga Ticks, Ixodes persulcatus (Acari: Ixodidae), and their Infection with Borrelia burgdorferi Sensu Lato

Abstract

In some studies the prevalence of tick infection (infection rate) and the intensity of infection are negatively correlated with unfed tick age (in the broad sense of this term). However, no special research has been carried out to consider the phenomenon thoroughly. The infection indices of the female taiga ticks, Ixodes persulcatus, infected with Borrelia burgdorferi s.l. were related to tick physiological age, an index that more precisely reflects tick physiological state than the time of tick collection in the field or the duration of tick survival under laboratory conditions. A novel quantitative technique of physiological age determination based on the evaluation of the ratios between sizes of the stable (scutum) and the changing (alloscutum) structures of the tick body was used. The age was estimated in accordance with the classical age-grade scale introduced by Balashov and a more fractional scale determined by the new technique. In total, 131 female ticks were examined for their infection and physiological age, 46 of which were infected with B. burgdorferi s.l. (mean infection rate 35.1%). The minimal intensity of infection was 0.4 bacterial cells per 100 fields of view whereas the maximal infection was 172 cells. There was no difference between the prevalence of infection in ticks of different physiological age. The intensity of infection obviously differed between ticks of different age groups in the scale introduced by Balashov but did not significantly differ between ticks of different age groups according to the fractional age-grade scale. The data concerning the relationships between Borrelia burgdorferi and unfed Ixodes ticks are considered.

Progressive behavioural, physiological and transcriptomic shifts over the course of prolonged starvation in ticks

“…Of epidemiological importance is the increase in activity and host-seeking behaviour observed in our starved ticks. Ticks can maintain pathogen infections through extended starvation (Uspensky, Kovalevskii, & Korenberg, 2006), are potentially more likely to encounter a host (this study) and take larger bloodmeals upon finding a host (Amin, 1969). Therefore, starved ticks may have an enhanced role as vectors of disease by composing a greater proportion of the questing population than ticks that have more recently fed.…”

Survival of Ixodes ricinus (Acari: Ixodidae) Under Challenging Conditions of Temperature and Humidity Is Influenced by Borrelia burgdorferi sensu lato Infection

“…It also was observed that infection by B. burgdorferi s.l. increased questing activity in Ixodes persulcatus Schulze (Naumov 1999 cited by Uspensky et al 2006) and host-Þnding efÞcacy in adult I. ricinus (Faulde and Robbins 2008).…”

“…was recorded compared with the previous and following years (L.G., unpublished data). In addition, Naumov (2003) (cited by Uspensky et al 2006) noted that there was a trend toward an increase in the longevity of adult I. ricinus and I. persulcatus infected by B. burgdorferi s.l. spirochetes.…”

Pitfalls in Tick and Tick-Borne Pathogens Research, Some Recommendations and a Call for Data Sharing

“…It is the manner of determining if a tick is "young" (probably newly molted) or if it has already spent a long time questing in the vegetation, thus depleting energy resources [9]. The classic method is to measure the fat contents of the tick as a proxy of its energy reserves [2,9,10]. This is an effective but time-consuming procedure.…”