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Steinau an der Straße, Germany

Karger A.,Friedrich Loeffler Institute | Kampen H.,Friedrich Loeffler Institute | Bettin B.,Friedrich Loeffler Institute | Dautel H.,IS Insect Services GmbH | And 4 more authors.
Ticks and Tick-borne Diseases | Year: 2012

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 possible using body parts and engorged animals. Spectra of developing . Ixodes ricinus eggs showed dramatic changes with time, suggesting that, beyond its usefulness for species determination, MALDI-typing may have applications in developmental biology. © 2012 Elsevier GmbH. Source

Rumer L.,Robert Koch Institute | Sheshukova O.,Robert Koch Institute | Dautel H.,IS Insect Services GmbH | Mantke O.D.,Robert Koch Institute | Niedrig M.,Robert Koch Institute
Vector-Borne and Zoonotic Diseases | Year: 2011

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 found to be the most favorable for primer design. Finally, for each of the three Ixodes species a PCR was developed amplifying only for the targeted species. One PCR amplified the entire ITS2 locus of the four species and allowed discrimination of D. reticulatus from the Ixodes species on the basis of the size difference of the respective PCR products. This PCR system was successfully tested for discrimination of the ticks at different maturation stages (larva, nymph, and adult) in engorged and unfed conditions, and therefore it may be useful for large-scale epidemiological studies. Differentiation between the closely related I. ricinus and I. persulcatus, the two species most often occurring in the tick-borne diseases in Eurasia, is of special importance. © 2011, Mary Ann Liebert, Inc. Source

Buchel K.,IS Insect Services GmbH | Bendin J.,IS Insect Services GmbH | Gharbi A.,IS Insect Services GmbH | Rahlenbeck S.,Umweltbundesamt | Dautel H.,IS Insect Services GmbH
Ticks and Tick-borne Diseases | Year: 2015

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 3.5-4. h. 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 5. h in nymphs of I. scapularis, but 8. h 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. © 2015 Elsevier GmbH. Source

Schmidt O.,University College Dublin | Dautel H.,IS Insect Services GmbH | Newton J.,Scottish Universities Environmental Research Center | Gray J.S.,University College Dublin
Ticks and Tick-borne Diseases | Year: 2011

This proof-of-concept study demonstrates that stable isotope ratios of nitrogen and carbon (expressed as δ13C and δ15N) 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 δ13C and 3.8 and 3.9‰ for δ15N. Both δ13C and δ15N 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. © 2011 Elsevier GmbH. Source

Dautel H.,IS Insect Services GmbH | Dippel C.,IS Insect Services GmbH | Werkhausen A.,IS Insect Services GmbH | Diller R.,Friedrich Loffler Institute
Ticks and Tick-borne Diseases | Year: 2013

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. © 2013 Elsevier GmbH. Source

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