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Determination of the ratios of natural stable isotopes (13C/12C and 15N/14N) in unfed Ixodes ricinus nymphs and adults, which, in their previous stage, fed on captive wild rodents (Apodemus sylvaticus and Myodes glareolus), wild birds... more
Determination of the ratios of natural stable isotopes (13C/12C and 15N/14N) in unfed Ixodes ricinus nymphs and adults, which, in their previous stage, fed on captive wild rodents (Apodemus sylvaticus and Myodes glareolus), wild birds (Parus major and Cyanistes caeruleus) or domestic ruminants (Ovis aries and Bos taurus), demonstrated that it is possible to identify each host category with confidence. First, the tick–blood spacing, which is the difference between values obtained from ticks and the blood of hosts that they had fed on in the previous stage, was consistent (152 spacings investigated from 15 host individuals in total). Second, potential confounding factors (tick age and sex) did not affect the discriminatory power of the isotope patterns, nor did different rearing conditions (room temperature vs. 4 °C) or the duration of development (maximum of 430 days). The findings that the tick–blood isotope spacings, across a diverse range of hosts, were similar and predictable, an...
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Today, the risk of getting tick-borne encephalitis (TBE) is still underestimated in many parts of Europe and worldwide. Therefore, the 14th meeting of the International Scientific Working Group on Tick-Borne Encephalitis (ISW-TBE) - a... more
Today, the risk of getting tick-borne encephalitis (TBE) is still underestimated in many parts of Europe and worldwide. Therefore, the 14th meeting of the International Scientific Working Group on Tick-Borne Encephalitis (ISW-TBE) - a group of neurologists, general practitioners, clinicians, travel physicians, virologists, pediatricians, and epidemiologists - was held under the title "Tick-borne encephalitis: an underestimated risk…still". Among the discussed issues were: TBE, an underestimated risk in children, a case report in two Dutch travelers, the very emotional report of a tick victim, an overview of the epidemiological situation, investigations to detect new TBE cases in Italy, TBE virus (TBEV) strains circulation in Northern Europe, TBE Program of the European Centre for Disease Prevention and Control (ECDC), efforts to increase the TBE vaccination rate in the Czech Republic, positioning statement of the World Health Organization (WHO), and TBE in dogs. To answer the question raised above: Yes, the risk of getting TBE is underestimated in children and adults, because awareness is still too low. It is still underestimated in several areas of Europe, where, for a lack of human cases, TBEV is thought to be absent. It is underestimated in travelers, because they still do not know enough about the risk, and diagnostic awareness in non-endemic countries is still low.
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Vector-borne pathogens manipulate their vertebrate hosts to enhance their transmission to arthropod vectors. The ability of vertebrate hosts to develop acquired immunity against arthropod vectors represents an existential threat for both... more
Vector-borne pathogens manipulate their vertebrate hosts to enhance their transmission to arthropod vectors. The ability of vertebrate hosts to develop acquired immunity against arthropod vectors represents an existential threat for both the vector and the pathogen. The purpose of the study was to test whether the tick-borne spirochete bacterium Borrelia afzelii could suppress the development of acquired immunity to its tick vector Ixodes ricinus in the bank vole Myodes glareolus, which is an important host for both the tick and the pathogen. We created a group of B. afzelii-infected bank voles and an uninfected control group by exposing lab-reared animals to infected or uninfected ticks. At 1, 2, and 3 months post-infection, all bank voles were infested with larval I. ricinus ticks. The bank voles developed a strong antibody response against tick salivary gland extract proteins. This anti-tick immunity had negative effects on tick fitness traits including engorged larval weight, un...
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In the past years test systems for the evaluation of repellents, attractants and insecticides/acaricides have been developed and further refined in our laboratory. A standardized laboratory test system for the evaluation of tick... more
In the past years test systems for the evaluation of repellents, attractants and insecticides/acaricides have been developed and further refined in our laboratory. A standardized laboratory test system for the evaluation of tick repellents (Moving-Object (MO) Bioassay) has been extensively used with Ixodes ricinus ticks. The system is based on a rotating drum equipped with a tick attachment site heated to skin temperature (35-36°C). Ticks approach the drum and cling to the passing by attachment site as they do in nature when attaching to a passing host. The system is sufficiently attractive such that as a mean 89% of I. ricinus nymphs (n=390), 93% of Australian I. holocyclus adults (n=180), and 88% of Rhipicephalus sanguineus adults (n=150) approach and attach to the drum. By covering the drum attachment site with repellent, distance repellency can be detected by a reduced number of ticks clinging to this site, whereas contact repellency is shown by an increased number of ticks drop...
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Understanding epidemiology of the tick-borne pathogens requires the accurate identification of the vector ticks. Morphological analysis of ticks is difficult and often leads to misidentification. Molecular techniques offer an alternative... more
Understanding epidemiology of the tick-borne pathogens requires the accurate identification of the vector ticks. Morphological analysis of ticks is difficult and often leads to misidentification. Molecular techniques offer an alternative approach of tick identification. To date, no practical and reliable molecular assays for discrimination of Euro-Asian ticks are available. Our aim was to develop such an assay for discrimination between four Euro-Asian tick species of high medical importance such as Ixodes ricinus, Ixodes persulcatus, Ixodes hexagonus, and Dermacentor reticulatus. As a basis, we have chosen conventional species-specific polymerase chain reaction (PCR), a technique providing a good combination of simplicity and reliability. The DNA information available on ticks was searched for orthologous loci containing stretches of sequence dissimilarity sufficient for designing species-specific primers. ITS2 locus (second internal transcribed region of the rRNA gene cluster) was...
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Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of crude bacterial samples has been introduced as a very cost-efficient and rapid, yet highly informative tool to identify and classify bacteria. The potential of... more
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of crude bacterial samples has been introduced as a very cost-efficient and rapid, yet highly informative tool to identify and classify bacteria. The potential of this approach to characterize whole animals, so far preferentially insects, is only evolving. Here, a simple protocol was developed to perform MALDI-MS analysis on extracts from whole ticks of 7 species and 4 developmental stages. Using commercially available software designed for the identification of bacteria, a reference database of spectra was constructed that allowed the species determination of ticks using larvae, nymphs, or adult individuals as starting material. Cluster analysis on the basis of MALDI mass spectra indicated that the primary determinant for the mass spectra was the species, followed by the developmental stages, which formed distinct clusters within the given species. With certain limitations, species identification was also poss...
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An updated and increased compilation of georeferenced tick locations in Germany is presented here. This data collection extends the dataset published some years ago by another 1448 new tick locations, 900 locations of which were digitized... more
An updated and increased compilation of georeferenced tick locations in Germany is presented here. This data collection extends the dataset published some years ago by another 1448 new tick locations, 900 locations of which were digitized from literature and 548 locations are published here for the first time. This means that a total of 3492 georeferenced tick locations is now available for Germany. The tick fauna of Germany includes two species of Argasidae in the genera Argas and Carios and 19 species of Ixodidae in the genera Dermacentor, Haemaphysalis, and Ixodes, altogether 21 tick species. In addition, three species of Ixodidae in the genera Hyalomma (each spring imported by migratory birds) and Rhipicephalus (occasionally imported by dogs returning from abroad with their owners) are included in the tick atlas. Of these, the georeferenced locations of 23 tick species are depicted in maps. The occurrence of the one remaining tick species, the recently described Ixodes inopinatu...
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The castor bean tick Ixodes ricinus (L.) is the principal vector for a variety of viral, bacterial, and protozoan pathogens causing a growing public-health issue over the past decades. However, a national density map of I. ricinus is... more
The castor bean tick Ixodes ricinus (L.) is the principal vector for a variety of viral, bacterial, and protozoan pathogens causing a growing public-health issue over the past decades. However, a national density map of I. ricinus is still missing. Here, I. ricinus nymphs in Germany were investigated by compiling a high-resolution map depicting the mean annually accumulated nymphal density, as observed by monthly flagging an area of 100 m2. Input data comprise ticks collected at 69 sampling sites. The model domain covers an area of about 357,000 km2 (regional scale). Two negative binomial regression models were fitted to the data to interpolate the tick densities to unsampled locations using bioclimatic variables and land cover, which were selected according to their significance by the Akaike information criterion (AIC). The default model was fitted to the complete dataset resulting in AIC = 842. An optimized model resulted in a significantly better value of AIC = 732. Tick densiti...
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ABSTRACT The occurrence of diapause and quiescence was investigated in Argas reflexus engorged larvae, nymphs I and nymphs II. For diapause experiments, larvae were maintained at five different locations: at constant 20°C long day (LD;... more
ABSTRACT The occurrence of diapause and quiescence was investigated in Argas reflexus engorged larvae, nymphs I and nymphs II. For diapause experiments, larvae were maintained at five different locations: at constant 20°C long day (LD; 17 h light:7 h dark) or short day (SD; 10 h light:14 h dark), at two locations with natural photoperiod and temperature and at one location with natural photoperiod but constant 15°C. At 20°C, diapause incidence was low in physiologically young larvae, increased with larval age, and then decreased to zero in specimens of increased physiological age. This pattern, observed both at constant LD and SD, suggests that the propensity to diapause changes with the physiological age of the unfed larva. The duration of diapause decreased with increasing larval physiological age at all locations, resulting in a seasonally synchronized moulting pattern. The results suggest that A. reflexus larvae are photoperiodically sensitive both before and after feeding and that decreasing daylengths may be particularly strong inductive stimuli. The developmental zero and thermal constant of the larvae were determined as 13.24°C and 220 degree-days, respectively. Degree-day measurements revealed that larval A. reflexus may enter a diapause of different length when fed between August and December and kept at natural daylength. Development of engorged nymphs I and nymphs II, but not of larvae, was ultimatively restricted at a temperature of 37.5°C, but immediately resumed at 25°C, demonstrating the occurrence of quiescence at high temperatures. Similarly, at a low temperature of 15°C, many nymphs I and II did not develop within 58 months, but did so successfully after transfer to 25°C, without additional food intake.
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... 2001. Meded., Leiden, 24, 281-391. CAGNOLI, M.; RIVA, G.; SIOLI, C.; FALAGIANI, P.; GENCHI, C., 1985: The use of RAST in diagnosis of lesions from pigeon-tick sting Argus reflexus reflexusFabricius 1794. Giornale di malattie infettive... more
... 2001. Meded., Leiden, 24, 281-391. CAGNOLI, M.; RIVA, G.; SIOLI, C.; FALAGIANI, P.; GENCHI, C., 1985: The use of RAST in diagnosis of lesions from pigeon-tick sting Argus reflexus reflexusFabricius 1794. Giornale di malattie infettive e parassitarie 37, 1425-1428. ...
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The goal of this paper is to present up-to-date maps depicting the geographical distribution of Dermacentor species in Europe based on georeferenced sampling sites. Therefore, a dataset was compiled, resulting in 1286 D. marginatus... more
The goal of this paper is to present up-to-date maps depicting the geographical distribution of Dermacentor species in Europe based on georeferenced sampling sites. Therefore, a dataset was compiled, resulting in 1286 D. marginatus (Sulzer, 1776) and 1209 D. reticulatus (Fabricius, 1794) locations. Special emphasis is given to the region of the European Alps depicting a presumable climate barrier of the mountains and to overlaps in the distribution of both species as well as on the situation in eastern European countries. For the latter newly described Dermacentor findings comprise 59 locations in Romania and 62 locations in Ukraine. The geographical distributions of both species in Europe range from Portugal to Ukraine (and continue to the east of Kazakhstan). Although it is well known that D. marginatus is adapted to a warmer and drier climate at more southern latitudes and D. reticulatus to a moderately moist climate at more northern latitudes, the distribution limits of both species were not well known. Here, the northern and southern distribution limits for both species in Europe, as determined from the georeferenced database, were specified for D. marginatus by the belt of 33-51° N latitude and for D. reticulatus by the belt of 41-57° N latitude. Thus, overlapping species distributions were found between 41° N and 51° N.
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Repellent efficacy of 10% EBAAP (3-[N-butyl-N-acetyl]-aminopropionic acid, ethyl ester) and 10% Icaridin ((2-(2-hydroxyethyl)-1-piperidinecarboxylic acid 1-methylpropyl ester)) were evaluated against 20% DEET... more
Repellent efficacy of 10% EBAAP (3-[N-butyl-N-acetyl]-aminopropionic acid, ethyl ester) and 10% Icaridin ((2-(2-hydroxyethyl)-1-piperidinecarboxylic acid 1-methylpropyl ester)) were evaluated against 20% DEET (N,N-diethyl-3-methylbenzamide) in human subject trials against ticks. Responses of host-seeking nymphs of the European castor bean tick (Ixodes ricinus L.; Acari: Ixodidae) and the North American blacklegged tick (I. scapularis Say; Acari: Ixodidae) were compared. Tests were carried out according to the US-EPA standard protocol with ethanolic solutions of the active ingredients of repellents being applied to the forearm of 10 volunteers. The upward movement of ticks was monitored until repellent failure taking up to 12.5 h. Application of 20% DEET resulted in median complete protection times (CPT; Kaplan-Meier median) between 4 and 4.5 h, while 10% EBAAP yielded CPTs of 3.5-4h. No significant differences were found between the efficacies of two repellents nor between the two species tested. The median of the CPT of a 10% Icaridin solution was 5h in nymphs of I. scapularis, but 8h in those of I. ricinus (P<0.01). Based on these studies, EBAAP and Icaridin are efficacious alternatives to DEET in their repellent activity against nymphs of the two Ixodes ticks with Icaridin demonstrating particularly promising results against I. ricinus. Future research should investigate whether similar results occur when adult Ixodes ticks or other tick species are tested.
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There is an interest in the development of repellents for personal protection of humans and animals against ticks. Evaluation of new substances or formulations needs adequate test procedures to show efficacy of the compounds. A variety of... more
There is an interest in the development of repellents for personal protection of humans and animals against ticks. Evaluation of new substances or formulations needs adequate test procedures to show efficacy of the compounds. A variety of repellent assays for ticks are described in the literature. Available biotests can be grouped in three categories (i) use of live hosts, (ii) use of some kind of tick attractant associated with hosts, or (iii) no use of attractants at all. The latter are often better to standardize and are cheap, but suffer from a poor ability to filter out weak repellents. The former two are usually more predictive in terms of forecasting the efficacy of the product under practical conditions, although sometimes difficult to standardize, particularly in the field, but usually expensive and time consuming. Therefore, recent developments concentrated on laboratory assays like the Moving-object bioassay or the human volunteer test, allowing the tick to display its host-seeking behaviour as close as possible to that shown in nature, yet offering a standardized procedure.
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In the European Union (EU), tick repellents for humans need to be registered and approved by the authorities in order to be marketed. As there are currently no specific technical guidelines for product evaluation, we compared 3 different... more
In the European Union (EU), tick repellents for humans need to be registered and approved by the authorities in order to be marketed. As there are currently no specific technical guidelines for product evaluation, we compared 3 different test methods: the mechanical moving object bioassay (MOB), and 2 assays involving human volunteers. For the latter, procedures according to the U.S. Environmental Protection Agency (EPA) and the Stiftung Warentest (StiWa), a German consumer care organization, were used. Two repellents, Autan(®) (AU), based on 20% Picaridin [2-(2-hydroxyethyl)-1-piperidinecarboxylic acid-1-methylpropyl ester], and ZeckWeck (ZW), based on 12.5g/100g Citriodiol™ (main compound: p-menthane-3,8-diol) were tested with all 3 assays. Three repellents, Anti Brumm(®) naturelle, based on 20% Citriodiol™ (main compound: p-menthane-3,8-diol), G090141, based on 20% EBAAP (ethyl buthyl acetyl aminopropionate), and G090152, based on 10% decanoic acid (capric acid), which is contained in Zanzarin(®), were tested according to the EPA and the StiWa procedures. The EPA assay indicated a significantly higher repellency of the products AU and G090141 than the StiWa test, but no difference between assays could be detected for the remaining 3 products. Also the corresponding protection times were significantly longer (approximately 4h) when determined according to EPA versus to StiWa for 3 of the products, whilst the difference was insignificant for ZW and G090152. Additionally, significantly lower numbers of ticks initially walked onto the repellent-treated skin when tested according to EPA versus to StiWa in all products except ZW and G090152. Thus, the StiWa protocol appears to pose higher demands on a repellent than the EPA method. Contrary to expectation, the MOB showed the same or even lower product efficacy when compared to the EPA and StiWa tests. Particularly, the percentage of ticks clinging to repellent-treated filter paper was significantly higher than the proportion of ticks walking onto treated skin in the other assays. This could mean that in nature more ticks may probably cling to a human protected by a given repellent than the EPA or the StiWa assay might suggest. Nevertheless, the MOB produced results that are quite similar to the tests involving human volunteers.
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The present paper describes a test procedure with human volunteers used for a comparative investigation of tick repellents. Eight commercially available repellents were tested against the tick Ixodes ricinus (L.) and several test criteria... more
The present paper describes a test procedure with human volunteers used for a comparative investigation of tick repellents. Eight commercially available repellents were tested against the tick Ixodes ricinus (L.) and several test criteria described. Ticks were placed on a copper plate situated on an arm or leg treated with repellent. While the arm or leg was kept vertically, it was observed whether or not a tick entered treated skin and walked a distance of at least 5 cm. No repellent was able to prevent more than 50% of the ticks from entering repellent-treated skin. Two repellents prevented >90% of the ticks from walking over the skin. Taking this as the test criterion, the other six products either repelled lower proportions of the ticks or showed no repellent effect at all. In the majority of repellents, ticks that managed to cross treated skin walked predominantly downwards. This behavior was contrary to the control, in which ticks preferred to walk upwards, and might be ind...
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Seasonal reproduction and embryonic development was investigated in Argas reflexus (F.) throughout a 5-yr period. Ticks were kept in desiccators at approximately 76% RH at 2 experimental sites--an attic and an outdoor aviary--that... more
Seasonal reproduction and embryonic development was investigated in Argas reflexus (F.) throughout a 5-yr period. Ticks were kept in desiccators at approximately 76% RH at 2 experimental sites--an attic and an outdoor aviary--that provided a natural photoperiod and temperature. Tick oviposition was limited to the summer months (June through August) regardless of the year of investigation and of the seasonal time of tick feeding. Engorged female ticks entered diapause between late July and late August. Ticks that had already started oviposition, stopped at that time and continued in the following year without requiring another blood meal. In the laboratory, A. reflexus eggs exhibited an upper lethal temperature (ULT50: 1-h exposure) of 44.1 degrees C (95% CL: 43.7-45.5 degrees C), which is in accordance with the increased egg mortality observed in the attic, where temperatures reached > or = 45 degrees C. A. reflexus eggs showed a low level of cold tolerance. Despite a supercoolin...
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ABSTRACT The European pigeon tick, Argas reflexus (F.), is in central Europe predominantly an urban pest parasitizing wild and domesticated pigeons, Columba livia. Under certain circumstances, however, it also bites humans, occasionally... more
ABSTRACT The European pigeon tick, Argas reflexus (F.), is in central Europe predominantly an urban pest parasitizing wild and domesticated pigeons, Columba livia. Under certain circumstances, however, it also bites humans, occasionally causing an IgE-mediated type-I allergy. Control of A. reflexus is very difficult because of a number of remarkable morphological, physiological, and behavioural features of the tick. The present study aimed at elucidating the distribution and the frequency of occurrence of A. reflexus in Berlin and its possible vector role for Borrelia burgdorferi sensu lato (s. l.). Buildings reported by occupiers to be infested with A. reflexus were personally examined. In addition, the carrier status of this soft tick for B. burgdorferi (s. l.) was investigated in three German towns by an indirect immunofluorescence assay. A total of 188 Berlin buildings was found to be infested with A. reflexus between 1989 and 1998. Infestations were found in 17 out of the 21 districts, clustering in the inner city. There was only a single Borrelia-positive tick out of 800 sampled in Berlin, Leipzig, and Hannover using the genus specific antibody H9724. The same tick was PCR-negative for B. burgdorferi outer surface protein A. Neither these results nor those of other studies on the occurrence of antibodies against B. burgdorferi in pigeons suggest that field populations of A. reflexus and/or pigeons in central Europe harbour the causative agent of Lyme borreliosis.
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Ticks are arthropods and the most important vectors of major human diseases after mosquitoes. Due to their impact on public health, in vitro and in vivo assays have been developed to identify molecules with repellent activities on ticks.... more
Ticks are arthropods and the most important vectors of major human diseases after mosquitoes. Due to their impact on public health, in vitro and in vivo assays have been developed to identify molecules with repellent activities on ticks. Repellents are useful to reduce tick bite exposure and the potential transmission of pathogens; they can be used topically or in impregnated clothing. Presently, mainly synthetic molecules are commercialized as skin repellents, e.g., N,N-diethyl-meta-toluamide (DEET), IR3535, picaridin or KBR 3023, and para-menthanediol. Permethrin is largely used for fabric impregnation. Intensive research has been conducted to identify new molecules with repellent activity and more recently, plant-derived molecules, as an alternative to synthetic molecules.
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ABSTRACT The occurrence of diapause and quiescence was investigated in Argas reflexus engorged larvae, nymphs I and nymphs II. For diapause experiments, larvae were maintained at five different locations: at constant 20°C long day (LD;... more
ABSTRACT The occurrence of diapause and quiescence was investigated in Argas reflexus engorged larvae, nymphs I and nymphs II. For diapause experiments, larvae were maintained at five different locations: at constant 20°C long day (LD; 17 h light:7 h dark) or short day (SD; 10 h light:14 h dark), at two locations with natural photoperiod and temperature and at one location with natural photoperiod but constant 15°C. At 20°C, diapause incidence was low in physiologically young larvae, increased with larval age, and then decreased to zero in specimens of increased physiological age. This pattern, observed both at constant LD and SD, suggests that the propensity to diapause changes with the physiological age of the unfed larva. The duration of diapause decreased with increasing larval physiological age at all locations, resulting in a seasonally synchronized moulting pattern. The results suggest that A. reflexus larvae are photoperiodically sensitive both before and after feeding and that decreasing daylengths may be particularly strong inductive stimuli. The developmental zero and thermal constant of the larvae were determined as 13.24°C and 220 degree-days, respectively. Degree-day measurements revealed that larval A. reflexus may enter a diapause of different length when fed between August and December and kept at natural daylength. Development of engorged nymphs I and nymphs II, but not of larvae, was ultimatively restricted at a temperature of 37.5°C, but immediately resumed at 25°C, demonstrating the occurrence of quiescence at high temperatures. Similarly, at a low temperature of 15°C, many nymphs I and II did not develop within 58 months, but did so successfully after transfer to 25°C, without additional food intake.
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Seasonal supercooling points (SCPs=temperature of crystallization) and cold hardiness were investigated in the indigenous hard tick, I. ricinus, and in A. reflexus, a soft tick introduced to Central Europe from the South. Both species... more
Seasonal supercooling points (SCPs=temperature of crystallization) and cold hardiness were investigated in the indigenous hard tick, I. ricinus, and in A. reflexus, a soft tick introduced to Central Europe from the South. Both species proved to be freeze-susceptible as well as highly susceptible to inoculative freezing. None of the postembryonic developmental stages of either species showed any distinct seasonal pattern of SCP. Unexpectedly, the introduced A. reflexus exhibited a distinctly higher degree of cold hardiness in terms of lower lethal temperature (LT(50): 24h exposure) as well as lethal time (T(50): time of survival at -10.1 degrees C) than I. ricinus. Engorged I. ricinus larvae as well as engorged summer acclimatized A. reflexus larvae showed some mortality at temperatures well above the SCP. This mortality was generally expressed as a failure of the following stage to eclose properly. A 10-day cold acclimation at +3 degrees C eliminated that kind of mortality in summer acclimatized A. reflexus larvae, but not in I. ricinus larvae. It was frequently observed that freezing of ticks resulted-possibly via leakage from the midgut-in a subsequent reddish brown discoloration of the ticks after thawing. Taking into account that discoloration was an indication of previous freezing, it was concluded, that after long-term exposure (for >/=30 days) at -10.1 degrees C, a temperature well above the SCP, some tick mortality could be observed that was not caused by previous freezing. Weighing experiments clearly demonstrated, that the level of dehydration was not critical for survival of A. reflexus during long-term cold exposure, even at low RH. This indicates, that cold-related factors other than freezing and dehydration were detrimental to this species.
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The supercooling capacity of nine laboratory-held species of ticks originating from different geographical areas, as well as five field-collected species from Germany, was investigated. All but one tick species showed mean supercooling... more
The supercooling capacity of nine laboratory-held species of ticks originating from different geographical areas, as well as five field-collected species from Germany, was investigated. All but one tick species showed mean supercooling points between about -17 and -23 degrees C, suggesting that the capacity to supercool to temperatures of < or = -17 degrees C might be an inherent property of many tick species unrelated to their geographic origin. Photoperiod did not influence the mean supercooling point in any of the species and there was also no distinct seasonal pattern of supercooling in seasonally acclimatized Dermacentor marginatus. Thus, the supercooling ability was independent of the presence/absence of diapause. The finding of thermal hysteresis in D. marginatus hemolymph raises the question of whether or not anti-freeze proteins are involved in the supercooling capacity of that species. An interspecies comparison revealed a weak negative correlation between relative water content and supercooling point of the ticks and an even weaker correlation between body mass or body water mass and the supercooling point. Since the ticks exhibited low supercooling points both before and shortly after feeding, the blood used as food should lack potent ice nucleators.
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... 2001. Meded., Leiden, 24, 281-391. CAGNOLI, M.; RIVA, G.; SIOLI, C.; FALAGIANI, P.; GENCHI, C., 1985: The use of RAST in diagnosis of lesions from pigeon-tick sting Argus reflexus reflexusFabricius 1794. Giornale di malattie infettive... more
... 2001. Meded., Leiden, 24, 281-391. CAGNOLI, M.; RIVA, G.; SIOLI, C.; FALAGIANI, P.; GENCHI, C., 1985: The use of RAST in diagnosis of lesions from pigeon-tick sting Argus reflexus reflexusFabricius 1794. Giornale di malattie infettive e parassitarie 37, 1425-1428. ...
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Local and systemic reactions can occur after bites of Argas reflexus (Argas), a soft tick parasitizing pigeons.
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Two studies were performed to elucidate the current distribution of the tick Dermacentor reticulatus in Germany. In the first one in 2003, a total of 365 dogs from 171 sites in the states of Berlin and Brandenburg was screened for ticks,... more
Two studies were performed to elucidate the current distribution of the tick Dermacentor reticulatus in Germany. In the first one in 2003, a total of 365 dogs from 171 sites in the states of Berlin and Brandenburg was screened for ticks, and the corresponding outdoor sites that the dogs usually visited were searched for host-seeking ticks by the flagging method. A total of 1155 ticks was removed from the dogs. The majority were Ixodes ricinus (88.5%), followed by D. reticulatus (9.1%) and I. hexagonus (2.4%). Altogether, 222 dogs carried I. ricinus (60.8%), 41 D. reticulatus (11.2%) and 15 I. hexagonus (4.1%) ticks. Based on scutal index determination, the removed I. ricinus and D. reticulatus had been feeding on the dogs for a mean of 4.0 and 4.5 days, respectively. The dogs infested with D. reticulatus lived at 26 different sites, all previously unknown as Dermacentor sites. Seven of the sites could be confirmed subsequently by flagging the vegetation for ticks. In the second stud...
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Zoonotic tick-borne diseases are an increasing health burden in Europe and there is speculation that this is partly due to climate change affecting vector biology and disease transmission. Data on the vector tick Ixodes ricinus suggest... more
Zoonotic tick-borne diseases are an increasing health burden in Europe and there is speculation that this is partly due to climate change affecting vector biology and disease transmission. Data on the vector tick Ixodes ricinus suggest that an extension of its northern and altitude range has been accompanied by an increased prevalence of tick-borne encephalitis. Climate change may also be partly responsible for the change in distribution of Dermacentor reticulatus. Increased winter activity of I. ricinus is probably due to warmer winters and a retrospective study suggests that hotter summers will change the dynamics and pattern of seasonal activity, resulting in the bulk of the tick population becoming active in the latter part of the year. Climate suitability models predict that eight important tick species are likely to establish more northern permanent populations in a climate-warming scenario. However, the complex ecology and epidemiology of such tick-borne diseases as Lyme borr...
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This proof-of-concept study demonstrates that stable isotope ratios of nitrogen and carbon (expressed as δ(13)C and δ(15)N) of host blood are faithfully reproduced in unfed nymphal Ixodes ricinus that developed from larvae fed on that... more
This proof-of-concept study demonstrates that stable isotope ratios of nitrogen and carbon (expressed as δ(13)C and δ(15)N) of host blood are faithfully reproduced in unfed nymphal Ixodes ricinus that developed from larvae fed on that host. Measured isotopic discrimination (i.e. the tick-blood spacing) was between -0.1 and 0.7‰ for δ(13)C and 3.8 and 3.9‰ for δ(15)N. Both δ(13)C and δ(15)N increased significantly with tick ageing. The isotopic analysis of unfed ticks has potential for determining the physiological age of unfed ticks, for identifying the season in which the previous stage had fed and for identifying the main hosts utilized by ticks.