Department of Biology and Parasitology

Background: The high competence of D. reticulatus in transmission of tick-borne pathogens prompts investigations of the effect of chemicals used as repellents and acaricides on the behaviour of the tick on the host. Therefore, this paper presents the effect of permethrin and deltamethrin on the attachment and feeding in this tick species. Findings: Attachment to rabbit skin of D. reticulatus females sprayed with pyrethroids and the effect of different doses thereof on feeding were assessed at a temperature of 20 ± 3°C and 50 % humidity. The dynamics of attachment of D. reticulatus females varied in a dose-dependent manner after the application of both pyrethroids. Within the first 0.5 h of the experiments, there was an over six-fold and over twelve-fold increase in the number of females attached to host skin after application of permethrin concentrations of 0.3906-0.7812 μg and 1.5625-3.1250 μg/1 specimen, respectively. In the case of deltamethrin, females treated with the dose of 0.0390 μg of the compound were able to attach to host skin only 4 hours after the infestation. The toxic activity of both pyrethroids increased the duration of the feeding period and decreased the body weight of engorged females and the feeding efficiency index. Conclusions: The accelerated attachment of D. reticulatus females caused by sublethal permethrin doses and delayed or inhibited attachment caused by deltamethrin suggest a necessity of careful selection of the type and dose of pyrethroids to protect hosts from tick attacks.

Introduction and objective. Expansion into new areas and the great epidemiological significance of the D. reticulatus tick in Europe prompts investigations of its ethology. Therefore, the locomotor activity of D. reticulatus adult stages in an optimal habitat during the spring and autumn activity periods was analysed. Materials and method. Marked D. reticulatus adults were placed at the central point of each experimental plot. At regular time intervals, specimens attached to the cloth used in the flagging method were collected, and the distance covered by the ticks was measured. In each collection round, the temperature and humidity level in the habitat was also measured. Results. Within 7 weeks, adult D. reticulatus ticks can cover an average distance of 60.71±44 cm. The locomotor activity of adult stages is greater during the spring than the autumn activity period. Questing, females cover a greater distance (66.35±100 cm) than male ticks (54.85±45 cm). Adult stages are characterised by greater aggressiveness 24 hours after being released, i.e. 30% of females and 19% of males attempt to attach to host skin. The locomotor activity in adult ticks depends on the humidity of the habitat (Z=-1.198; p=0.050). The temperature does not affect tick walking. Conclusions. Given the low rates of horizontal locomotion of adult D. reticulatus ticks, the prevalence of the species in nature is determined by the presence of their hosts and humidity conditions ensuring their further development and survival. The dependence of D. reticulatus locomotor activity and aggressiveness on the humidity level implies an increased risk of host attacks in locations and periods that offer favourable humidity conditions for this species.

It was proved that transmission of some pathogens may occur between infected and uninfected ticks co-feeding on a host in the absence of systemic infection. The effect was studied of co-feeding of two different tick species Ixodes ricinus and Dermacentor reticulatus on the course of the non-parasitic stage. Species chosen for the experiment may share their habitats and co-infest animals in nature. In the course of the study the process of egg maturation, oviposition and larval hatching were investigated. In order to estimate if co-feeding influence can counteract host immunity, three subsequent infestations of rabbits were analyzed. Mono-specific groups values of such a parameters as egg amount, number of eggs per 1 mg of female engorgement weight, female oviposition weight loss, hatching success were higher in inter-specific groups were compared. The results indicate that co-feeding with other tick species may partially reduce the influence of host resistance in subsequent infestat...

Two pyrethroids, deltamethrin (D) and alphacypermethrin (AC), have been used as commercial products for tick control worldwide. However, the effects of sublethal doses of these compounds on various tick species and their developmental stages have not been fully explored yet, although such knowledge could contribute to a more effective application of both pyrethroids and simultaneous reduction of their costs and undesirable side effects, including the harmful impact on other organisms and environmental contamination. This study investigates the effect of sublethal concentrations of D and AC applied to engorged females on the fecundity, development of eggs and larvae, and the number of offspring in the Ixodes ricinus (L.) tick, which is the most important vector of tick-borne diseases of humans in Europe. After detachment from rabbit's skin, fully engorged I. ricinus females were treated with 20 μl of pyrethroid solutions at five concentrations from 0.01562 to 0.25% and kept at 28 °C and 75% relative humidity. The impact of the pyrethroids on maturation and development of eggs as well as development of larvae was assessed based on parameters of the preoviposition and oviposition periods and the course of embryogenesis and egg hatch. The investigations have shown that both tested acaricides reduce the reproductive rate in I. ricinus females by inhibition of egg development and disturb embryonic development and larval hatch. Females did not lay eggs at concentrations higher than 0.0625% AC and 0.125% D. The lower concentrations of both pyrethroids disturbed or inhibited the embryogenesis and egg hatch in I. ricinus.

Objective. This study presents for the first time a case of Hyalomma excavatum hyperparasitism and an analysis of this phenomenon in terms of its potential role in the biology of ticks and epidemiology of tick-borne diseases. Materials and method. Two partially engorged H. excavatum females, one fully engorged female, and 5 males were collected from a naïve rabbit and placed together in a rearing chamber at a temperature of 25 °C and 75% humidity. Results. 3-4 days after tick detachment from the host's skin, one partially engorged H. excavatum female was observed attached to the idiosoma of the fully engorged conspecific female. Conclusions. This study and observations of other authors confirm that partially engorged ixodid ticks can re-infest the host, and even co-feeding fully engorged ticks in order to collect the blood meal that is indispensable for important physiological processes. However, inefficient feeding of a partially engorged female on another conspecific female may reduce its reproductive performance and disturb the development of eggs and larvae. It seems that parasitism of a tick on another conspecific specimen, when at least one of them is infected by a microorganism, may be a yet poorly explored route of transmission of pathogens or symbionts between the ticks. Initiation of feeding by a hungry or partially engorged tick on a fully engorged specimen is an attempt to obtain food in the drastic conditions of the absence of a target host. Tick hyperparasitism with concurrent pathogen transmission can contribute to the genospecific diversity of pathogens in vectors and hosts.

Studies on diurnal activity and factors affecting the questing behavior in Dermacentor reticulatus (F.) adults were conducted in an open-type habitat in eastern Poland (51Њ 15Ј N, 22Њ 36Ј E). Observations, for 25 min each, were made at 2-h intervals between 1000 and 1800 hours. during the autumn (from late September to mid-October 2000) and spring (from late April to mid-May 2001) activity peaks. The questing behavior of adult D. reticulatus ticks depended on the time of the day and season. The autumn activity was higher than that in spring, yet both these periods were characterized by a rising trend from the morning to early afternoon with a peak at Ϸ1400 hours (on average 40 and 30 specimens per one collection, respectively). In spring, the high activity (on average 31.8 specimens/ collection) persisted until late afternoon (1800 hours), while in the autumn period it declined before nightfall (on average 21.4 specimens/collection at 1800 hours). Females predominated over males in both seasonal periods of activity and greater differences in the sex ratio were recorded in the spring. We found a negative correlation between the diurnal activity of the adult ticks and temperature and between the number of active ticks and the length of day both in the autumn and spring. However, no statistically signiÞcant correlation was demonstrated between the diurnal activity of adult ticks and humidity. The investigations show that, in addition to environmental factors, tick host-seeking behavior is dependent on the activity of their hosts and biological traits of this species.

Background: The action of chemical compounds on the Palaearctic tick D. reticulatus (Fabricius) (Acari: Amblyomminae) has been poorly investigated so far. Therefore, the effects of application of permethrin on engorged D. reticulatus females have been assessed, and the survival rate for the different developmental stages of the tick species in its non-parasitic phase of the life cycle was determined upon application of the pyrethroid. Methods: Each engorged D. reticulatus female, egg batch, unfed larvae (50 specimens), or unfed nymphs (10 specimens) were sprayed with 20 μl of 0.015625%-0.250% solutions of a Coopex WP preparation, which corresponded to 0.78125-12.5 μg of permethrin, respectively. The effect of permethrin in the preoviposition and oviposition periods was assessed based on the length of the egg development period, number of females capable of laying eggs, number and weight of eggs laid by the females, and indicators of female reproductive rate. Delayed effects of the action of the various permethrin doses were determined by quantitative and qualitative analysis of the course of embryonic development and larval hatch. The effect of permethrin on survival of the different tick stages was assessed at a temperature of 25°C and 90% RH 48 hours after application of permethrin to one to three day-old D. reticulatus eggs, seven to ten-day-old unfed larvae and nymphs. Results: The investigations demonstrated that at the doses applied permethrin decreased the reproductive rate of females, but only at the dose of 6.25 μg/1 specimen was the mean number of laid eggs drastically reduced, which may result in a decrease in tick abundance already in the first generation. The embryonic development of the eggs laid by the females treated with 6.25 and 12.5 μg of permethrin/1 specimen was highly disturbed. Irrespective of the permethrin dose applied, all eggs died within 48 hours after application. 100% of unfed D. reticulatus larvae and nymphs died within 48 hours after application of permethrin doses of 6.25 μg/50 specimens and 12.5 μg/10 specimens, respectively. Conclusions: Permethrin can be recommended for D. reticulatus control, particularly in the case of tick resistance to other chemical substances.

Introduction. Ixodes ricinus tick is of great medical and veterinary importance and has a wide range of geographical distribution. The study presents the effect of permethrin (Per) and cypermethrin (CM) on engorged I. ricinus females. Materials and method. The effect of perythroids studied on engorged I. ricinus females was assessed on the basis of the pre-oviposition and oviposition period. Remote effects of Per and CM application were assessed by investigation of the length and course of embryonic development and larval hatching from eggs laid by pyrethroid-treated females. Per (Copex WP) was used at doses of 0.78125-25.0 µg/1 specimen, and CM (Kordon 10WP) was applied at 0.3125-10.0 µg/1 specimen. Immediately after the feeding period, I. ricinus females were sprayed with 20 µl of a pyrethroid solution and kept at 28 °C and 75%RH. Results. The experiments demonstrated that CM exerted a stronger toxic effect on I. ricinus females than Per. The lowest doses of CM doubled the length of the pre-oviposition period while its highest doses prolonged the period nearly three times compared with the control. The pyrethroids applied reduced the number and weight of eggs and changed the parameters of the oviposition process. Application of the tested pyrethroid doses led to disturbances in the embryonic development of I. ricinus, i.e. the development was prolonged, few normal larvae hatched, numerous eggs and embryos at various developmental stages died, and larval hatch was inhibited. Conclusions. Knowledge about the sensitivity of engorged females to different doses of the tested pyrethroids and the remote effects of their action can be used in practice for tick control among livestock animals, and the reduction of tick population abundance in the environment.

Introduction. Despite the increased rates of infestations with I. ricinus (Ir) and D. reticulatus (Dr) ticks observed over the last decade, no effective control methods have been developed so far. The present study was focused on assessment of the action of pyrethroids on these both tick species. Materials and method. The different doses of four pyrethroids, i.e. deltamethrin-D (K-Othrine), permethrin-P (Copex WP), cypermethrin-C (Kordon 10WP), and alphacypermethrin-AC (Alfasekt 5SC) were tested. The LD 50 for each tested compound was also determined for both tick species. Unengorged and engorged (maintained on rabbit skin) tick females were sprayed with 20ml of 0.01563-0.50% solutions of the tested preparations. Results. The investigations showed that sensitivity of Ir and Dr to the tested pyrethroids, but the effects exerted by the different doses varied between both tick species and between engorged and unengorged females in these species. The strongest toxic effect on unengorged and engorged Ir and Dr females was exerted by D, whereas the effect of AC was weaker. The LD 50 (in µg/1 g b.w.

Investigations of the abundance and seasonal activity of adult D. reticulatus in relation to the eff ect of climatic conditions (temperature, humidity) and the photoperiod on host-seeking behaviour were conducted in eastern Poland (51°25'N) in 1999-2000. D. reticulatus host-seeking activity was observed between the end of March at 5°C temperature and 89% humidity, and the beginning of December at 6°C temperature and 92% humidity. The peak autumn activity found between September – November was more than 2-fold higher than the spring peak, which occurred between April – May. The activity of females, males, and the total number of adult ticks was correlated with the temperature (p<0.01) and photoperiod (p<0.01); additionally, no dependency was found between adult tick activity and humidity of the environment (p>0.05). Females predominated throughout almost the entire activity period, but the ratios between females and males varied in the particular seasons. Males predomina...

Investigations into the effect of the intensity of invasion on tick-questing behaviour were conducted on 3 groups of rabbits: 1) 10 females and 5 males, 2) 20 females and 10 males, 3) 40 females and 20 males in the case of I. ricinus, whereas in the case of D. reticulatus, another three groups were used: 1) 10 females and 15 males, 2) 20 females and 15 males, 3) 40 females and 15 males. Given the different invasion intensities, no significant difference was found in the time of attachment to the host (p=0.3773) or in the feeding period (p=0.1051) for Ixodes ricinus females. In turn, body weight of engorged females exhibited highly significant differences (p=0.0021) between the groups, particularly in the least (0.3551±0.0739 mg) (p=0.0027) and most numerous groups (0.2752±0.0964 g) (p=0.0017). In the case of D. reticulatus, the length of the skin attachment period did not show statistically significant differences (p=0.4036) between the groups consisting of different numbers of tick...

Investigations into the abundance of adult D. reticulatus in relation to the effect of climatic conditions (temperature, humidity) on host-seeking behaviour were conducted during the autumn (September-October) and spring (May) activity peaks in 2008-2009 in eastern Poland (51°25'N). The study was conducted in the same habitat where similar examinations were performed in 1999-2000. A comparative analysis revealed that the abundance of D. reticulatus had almost doubled within 10 years. Analysis of data on the humidity and temperature conditions prevailing during tick collection, and on tick abundance in the respective study periods in 1999-2000 and 2008-2009, as well as absence of climatic changes over many years, indicate that the increase in the numbers of ticks may have been a result of a multitude of other factors, e.g. weather or environmental conditions favourable for ticks and their hosts. The substantial differences in D. reticulatus abundance observed during the autumn ac...

Background: Given the sympatric occurrence in some regions of Europe and the great epidemiological significance of D. reticulatus and D. marginatus species, we investigated the behaviour of these ticks during inter-specific and mono-specific host infestations. Findings: The investigations were conducted on rabbits at 20 ± 3°C and humidity of 38 ± 1 %. The inter-specific infestations groups consisted of 20 females and ten males of D. marginatus and 20 females and ten males of D. reticulatus on each host, whereas mono-specific infestations involved 40 females and 20 males of each species. The investigations have demonstrated competition between the two tick species resulting in modification of the behaviour on the host and the feeding course in D. marginatus females by the presence of D. reticulatus. In the inter-specific group, D. marginatus females attached for a longer time (mean 2.74 ± 1.12 h) than in the mono-specific group (mean 1.24 ± 0.97 h) (p < 0.0001). The feeding period of these females was shorter (9.45 ± 1.30 days) than in the mono-specific group (13.15 ± 2.53 days) (p < 0.0001), but they exhibited a statistically significantly higher body weight in comparison with the females from the mono-specific infestation (p = 0.0155). In D. reticulatus females, no significant difference was found in the host attachment and feeding rates between the mono-specific and inter-specific groups. Conclusions: The differences in the behaviour of the females from both species during co-feeding reflect physiological adaptation to environmental conditions, which enables them to ingest blood and reproduce. During co-feeding of D. reticulatus and D. marginatus on the same host, two inter-specific systems with different physiological features are formed, which may influence the transmission of tick-borne pathogens.

Occurrence of co-infections with various pathogens in ixodid ticks creates a risk of increased severity of tick-borne diseases in humans and animals exposed to bite of the ticks carrying multiple pathogens. Accordingly, co-infections in ticks were subject of numerous analyses, but almost exclusively with regard to Ixodes ricinus complex whereas potential tick vectors belonging to other genera were much less studied. Taking into consideration the role of Dermacentor reticulatus in the transmission of various pathogens, we carried out for the first time the comprehensive statistical analysis of co-infections occurring in this tick species. An attempt was made to determine the significance of the associations between 6 different pathogens occurring in D. reticulatus (Tick-borne encephalitis virus = TBEV, Anaplasma phagocytophilum, Rickettsia raoultii, Borrelia burgdorferi s. l., Babesia spp., Toxoplasma gondii), using 2 statistical methods: determination of Odds Ratios (ORs) and the Fi...

Background: The territorial expansion and increased population size of haematophagous arthropods (i.e., the castor bean tick Ixodes ricinus (Ixodida: Ixodidae) and the deer ked Lipoptena cervi (Diptera: Hippoboscidae)) has enhanced the risk of human infestations in Europe. The aim of our study was to present skin lesions induced by tick and deer ked bites in patients from recreational forest regions in southeastern Poland and pay attention to features of skin changes that may be useful in differential diagnosis. Methods: We compare the skin lesions after I. ricinus and L. cervi bite and draw attention to the biological and ecological traits of both ectoparasites, which may be diagnostically relevant for determination of the cause of skin symptoms reported by patients. Results: I. ricinus bites lead to development of erythematous-infiltrative poorly demarcated lesions with a centrally located bite mark, which usually disappears within one to several days. In turn, L. cervi bites leav...

Rickettsiae from the spotted fever group, i.e. the etiological agents of tick-borne lymphadenopathy/Dermacentor-borne necrotic erythema and lymphadenopathy (TIBOLA /DEBONEL) syndrome, are associated with ticks, including Dermacentor marginatus and Dermacentor reticulatus. The expansion of these ticks into new areas increases the risk of infection of their hosts with tick-borne pathogens. The study summarises the importance of 2 species from the genus Dermacentor, i.e. D. marginatus and D. reticulatus, in the spread of spotted fever group rickettsiae in various regions of Europe. The study also focuses on the determinants of the presence of vectors and transmission of rickettsiae, as well as the effects of human infections with these pathogens. The climate changes observed nowadays affect vectors and increase the incidence and spread of tick-borne diseases worldwide. Due to the existing risk of exposure to an increasing number of people, knowledge about the course of these serious diseases and their etiological factors should be disseminated among healthcare professionals as well as in society. There is a great challenge for epidemiological services to provide access to medical and veterinary facilities in order to diagnose and treat rickettsioses. Therefore, the development of a strategy for tick control and the popularisation of knowledge concerning prophylaxis of tick-borne diseases is indispensable.

Ticks are hematophagous ectoparasites of humans and animals. These arthropods employ different strategies in their host-seeking activity; most often, it is the “nest”- and “pasture-questing” behaviour. Some species, e.g., Dermacentor reticulatus, exhibit both types of activity depending on their developmental stage. The aim of the present study was to investigate the host-seeking activity of adult D. reticulatus ticks in the eastern part of Poland. To this end, ticks were collected with the flagging method during their seasonal activity in three different types of habitat. Active specimens were marked with a permanent marker and then released. This was repeated consistently at 7-day intervals using a different colour of the marker each time, which allowed tracking the questing activity of the specimens. Most frequently, repetitive tick activity (repeated up to seven times) was noted in a locality surrounded by urban developments. In an agriculturally unused open meadow habitat, 69.9...

Background: Scabies (caused by Sarcoptes scabiei var. hominis) and pediculosis (caused by Pediculus humanus) are infectious diseases common in educational institutions and long-term care centres. The aim of the study was to assess the scale of the phenomenon in confinement conditions favouring the spread of these parasitoses. Methods: Data on the prevalence of scabies (2001–2015) and pediculosis (2008–2015) in Polish prisoners were provided by the Central Board of Prison Service. The information for the period between 2010 and 2015 in the Lublin Province was obtained from the District Inspectorate of the Prison Service in Lublin. Correlations between the prevalence of scabies and pediculosis and the number of prisoners were analysed, as well as correlations between the number of passes granted to prisoners and the prevalence of scabies and pediculosis in incarcerated individuals. Results: The prevalence of scabies and pediculosis in Polish prisoners has been estimated at 2.3% and 1....

This opinion piece highlights the role of migratory birds in the spread of ticks and their role in the circulation and dissemination of pathogens in Europe. Birds with different lifestyles, i.e., non-migrants residing in a specific area, or short-, medium-, and long-distance migrants, migrating within one or several distant geographical regions are carriers of a number of ticks and tick-borne pathogens. During seasonal migrations, birds that cover long distances over a short time and stay temporarily in different habitats can introduce tick and pathogen species in areas where they have never occurred. An increase in the geographical range of ticks as well as the global climate changes affecting the pathogens, vectors, and their hosts increase the incidence and the spread of emerging tick-borne diseases worldwide. Tick infestations of birds varied between regions depends on the rhythms of tick seasonal activity and the bird migration rhythms determined by for example, climatic and en...