Ticks (Family Ixodidae) spend most of their life cycle as immature stages in the soil and litter, and as any other soil invertebrates, are likely to be controlled top-down by soil-dwelling predators. To date, the ability of soil invertebrate predators to control ixodid tick population remains little known, partly due to methodological difficulties. In the current study, we developed and successfully tested a novel method of labeling live Ixodes ricinus (L., 1758) (Ixodida: Ixodidae) nymphs with a 15N isotope label. Labeled ticks were used in a small-scale 8-day-long microcosm experiment to reveal soil predators attacking nymphs. Only a small fraction (4.1% of all samples) of soil generalist predators preyed upon nymphs. A strong 15N label was found in 5 predator species, namely 2 spiders (Pachygnatha listeri Sundevall, 1830, Tetragnathidae and Ozyptila sp., Theridiidae), 2 gamasid mites (Pergamasus beklemischevi Sellnick, 1929 and Pergamasus quisquiliarum [Canestrini, 1882], Parasitidae), and 1 staphylinid beetle (Geostiba circellaris [Gravenhorst, 1806], Staphylinidae). The isotopic labeling can be a useful tool in revealing a range of invertebrate predators that can control tick populations in soil.
- MeSH
- Coleoptera * MeSH
- Ixodidae * MeSH
- Isotope Labeling MeSH
- Ixodes * MeSH
- Nymph MeSH
- Soil MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
Kočka patří k nejstarším domestikovaným zvířatům žijícím vedle člověka již několik tisíciletí. Ve spektru endoparazitů u domácích koček dominují druhy parazitů s heteroxenním vývojovým cyklem adaptovaným na vztah mezi predátorem a jeho kořistí. Poznání tasemnic v populacích koček v ÈR zásadně ovlivňuje to, že data z toulavých, městských nebo „outdoorových“ koček je obtížné vůbec získat. Představy o parazitofauně českých koček tak pochází především z vyšetřování koček typicky domácích, kde je výskyt heteroxenních parazitů velmi nízký. Tasemnice koček v ÈR zahrnují především Taenia taeniaeformis a Dipylidium caninum; alarmující je ale riziko možného zapojení kočky do cyklu E. multilocularis, vyvolávající významné orgánové infekce člověka. Odpověď na otázku, jak významným rezervoárem tasemnice Echinococcus multilocularis kočka je, zasluhuje v ÈR intenzivní výzkum.
Cats belong among the oldest domesticated animals, living side by side with humans for several millennia. Spectrum of endoparasites of domestic cats is dominated by parasites with heteroxenous life cycles, cycling among the predators and their prey. Knowledge on tapeworms in cats in Czechia is influenced by a fact, that data from street, stray or feral cats are difficult to obtain. Our knowledge thus originates mostly from indoor cats, where the occurrence of heteroxenous parasites is very low. Most frequently detected tapeworms in cats are Taenia taeniaeformis and Dipylidium caninum. However, there is an alarming risk of involvement of cats in the life cycle of Echinococcus multilocularis, causing severe organ echinococcosis in humans. Yet, answer to the question of the importance of cats as a reservoir of E. multilocularis in Czechia requires intense research.
Freshwater ecosystems are negatively impacted by various pollutants, from agricultural, urban and industrial wastewater, with metals being one of the largest concerns. Moreover, freshwater ecosystems are often affected by alien species introductions that can modify habitats and trophic relationships. Accordingly, the threat posed by metals interacts with those by alien species, since the latter can accumulate and transfer these substances across the food web to higher trophic levels. How metals transfer within such communities is little studied. We analysed the concentration of 14 metals/metalloids (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, Se, Zn, hereafter 'metal(s)') of eight fish and three crustacean species co-existing in the Arno River (Central Italy), most of which were alien. To assess the pathway of contaminants within the community, we coupled metal analysis with carbon and nitrogen stable isotope analysis derived from the same specimens. Crustaceans showed higher metal concentration than fish, except for Cd, Hg and Se that were higher in fish. We found evidence of trophic transfer for six metals (Cd, Cr, Hg, Mg, Se, Zn). Additionally, ontogenetic differences and differences among various fish tissues (muscle, liver, and gills) were found in metals concentration. Considerable biomagnification along the trophic chain was found for Hg, while other metals were found to biodilute. Using stable isotopes and Hg as a third diet tracer, we refined the estimations of consumed preys in the diet previously reconstructed with stable isotope mixing models. Alien species reach high biomass and can both survive to and accumulate high pollutants concentrations, potentially posing a risk for their predators and humans. A combined effect of environmental filtering and increased competition may potentially contribute to the disappearance of native species with lower tolerances.
- MeSH
- Water Pollutants, Chemical * analysis MeSH
- Ecosystem MeSH
- Humans MeSH
- Environmental Monitoring MeSH
- Fresh Water MeSH
- Metals, Heavy * analysis MeSH
- Introduced Species MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Italy MeSH
Acoustic signals serving intraspecific communication by predators are perceived by potential prey as warning signals. We analysed the acoustic characteristics of howling of wolves and found a striking similarity to the warning sounds of technical sirens. We hypothesize that the effectivity of sirens as warning signals has been enhanced by natural sensory predisposition of humans to get alerted by howling of wolves, with which they have a long history of coexistence. Psychoacoustic similarity of both stimuli seems to be supported by the fact that wolves and dogs perceive the sound of technical sirens as a relevant releasing supernormal stimulus and reply to it with howling. Inspiration by naturally occurring acoustic aposematic signals might become an interesting example of biomimetics in designing new warning sound systems.
- MeSH
- Humans MeSH
- Emergencies * MeSH
- Predatory Behavior physiology MeSH
- Dogs MeSH
- Wolves physiology MeSH
- Vocalization, Animal physiology MeSH
- Animals MeSH
- Sound * MeSH
- Check Tag
- Humans MeSH
- Dogs MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
Although glyphosate is widely used for weed pest control, it might have negative side effects on natural enemies. Wolf spiders are one of the most representative predators found on soybean crops in Uruguay, preying on a wide variety of potential pests. However, the sublethal effects that pesticides might have on this group have been poorly explored for South American species. Herein, we explored the sublethal effects of glyphosate on the functional response of the wolf spider Hogna cf. bivittata against three potential pest insects, namely ant (Acromyrmex sp.), caterpillar (Anticarsia gemmatalis), and cricket (Miogryllus sp.). We contaminated residually adult females of the species Hogna cf. bivittata with glyphosate (Roundup®) and compared their functional response against non-contaminated spiders. We did not observe any mortality during the study. We found that overall Hogna cf. bivittata showed a functional response type II against crickets and caterpillars but no functional response to ants. Contaminated spiders killed less ants and caterpillars in comparison to the control group, probably as a consequence of the irritating effects of glyphosate. We did not observe differences in functional response to crickets at the evaluated densities, probably as a consequence of the low capture rate against this prey. Although glyphosate does not specifically target spiders, it might have negative sublethal effects on native predators such as Hogna cf. bivittata. Further studies should explore effect of glyphosate on other native predators from South American crops.
- MeSH
- Ants MeSH
- Glycine analogs & derivatives toxicity MeSH
- Gryllidae MeSH
- Moths MeSH
- Spiders drug effects MeSH
- Pesticides toxicity MeSH
- Predatory Behavior drug effects MeSH
- Crops, Agricultural MeSH
- Animals MeSH
- Check Tag
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Uruguay MeSH
Heterotrophic nanoflagellates (HNF) are considered as major planktonic bacterivores, however, larger HNF taxa can also be important predators of eukaryotes. To examine this trophic cascading, natural protistan communities from a freshwater reservoir were released from grazing pressure by zooplankton via filtration through 10- and 5-µm filters, yielding microbial food webs of different complexity. Protistan growth was stimulated by amendments of five Limnohabitans strains, thus yielding five prey-specific treatments distinctly modulating protistan communities in 10- versus 5-µm fractions. HNF dynamics was tracked by applying five eukaryotic fluorescence in situ hybridization probes covering 55-90% of total flagellates. During the first experimental part, mainly small bacterivorous Cryptophyceae prevailed, with significantly higher abundances in 5-µm treatments. Larger predatory flagellates affiliating with Katablepharidacea and one Cercozoan lineage (increasing to up to 28% of total HNF) proliferated towards the experimental endpoint, having obviously small phagocytized HNF in their food vacuoles. These predatory flagellates reached higher abundances in 10-µm treatments, where small ciliate predators and flagellate hunters also (Urotricha spp., Balanion planctonicum) dominated the ciliate assemblage. Overall, our study reports pronounced cascading effects from bacteria to bacterivorous HNF, predatory HNF and ciliates in highly treatment-specific fashions, defined by both prey-food characteristics and feeding modes of predominating protists.
- MeSH
- Cercozoa * MeSH
- Cryptophyta MeSH
- In Situ Hybridization, Fluorescence MeSH
- Food Chain * MeSH
- Fresh Water MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Winter provides many challenges for terrestrial arthropods, including low temperatures and decreased food availability. Most arthropods are dormant in the winter and resume activity when conditions are favorable, but a select few species remain active during winter. Winter activity is thought to provide a head start on spring growth and reproduction, but few studies have explicitly tested this idea or investigated tradeoffs associated with winter activity. Here, we detail biochemical changes in overwintering winter-active wolf spiders, Schizocosa stridulans, to test the hypothesis that winter activity promotes growth and energy balance. We also quantified levels of putative cryoprotectants throughout winter to test the prediction that winter activity is incompatible with biochemical adaptations for coping with extreme cold. Body mass of juveniles increased 3.5-fold across winter, providing empirical evidence that winter activity promotes growth and therefore advancement of spring reproduction. While spiders maintained protein content throughout most of the winter, lipid content decreased steadily, suggesting either a lack of available prey to maintain lipids, or more likely, an allometric shift in body composition as spiders grew larger. Carbohydrate content showed no clear seasonal trend but also tended to be higher at the beginning of the winter. Finally, we tested the hypothesis that winter activity is incompatible with cryoprotectant accumulation. However, we observed accumulation of glycerol, myo-inositol, and several other cryoprotectants, although levels were lower than those typically observed in overwintering arthropods. Together, our results indicate that winter-active wolf spiders grow during the winter, and while cryoprotectant accumulation was observed in the winter, the modest levels relative to other species could make them susceptible to extreme winter events.
- MeSH
- Energy Metabolism * MeSH
- Adaptation, Physiological MeSH
- Glycerol analysis MeSH
- Body Mass Index MeSH
- Inositol analysis MeSH
- Cryoprotective Agents analysis MeSH
- Lipids analysis MeSH
- Cold Temperature adverse effects MeSH
- Spiders growth & development metabolism MeSH
- Predatory Behavior MeSH
- Proteins analysis MeSH
- Seasons MeSH
- Reproduction MeSH
- Carbohydrates analysis MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Digit ratio is a morphological feature regarded as a biomarker of the balance of sex hormones during early development. The exposure of embryos to a set of sex hormones and the mutual relations between those hormones cause the emergence of individual morphological and/or behavioural characteristics as well as differences between sexes. We have thus hypothesised that differences in one of these morphological traits-digit ratio-may be a proxy representing a tendency towards tail autotomy. The aim of this study is to investigate the digit ratio (2D:3D, 2D:4D, 3D:4D) of the sand lizard, Lacerta agilis, Lacertidae, a species characterised by well-developed sexual dimorphism, whereby females are larger than males. We also tested associations between patterns in digit ratio and caudal autotomy, a common defensive mechanism among lizards. To our knowledge, the relationship between a tendency towards autotomy and digit ratio pattern has never been researched. To date, studies on autotomy have mainly focused on the consequences, costs or evolutionary background of tail loss. Hence, researchers examined mostly the frequency of autotomy in the context of predatory pressure or habitat conditions, omitting an individual's behavioural tendency to shed its tail. However, behavioural traits can affect an individual's exposure to predator attack and consequently the need to use an anti-predator strategy. Thus, following this logic, dropping the tail may be the result of the lizard's intraspecific personality characteristics, resulting from the effect of hormones on behaviour or innate traits. Therefore, we suggest that the inclusion of autotomy as a factor explaining observed digit ratio patterns and their variability between taxa has great potential. We used computerised measurements of photographed limbs to determine the length of digits. We found that the digit ratios for all four limbs were significantly lower in females than in males, excluding the 3D:4D ratio for the right hindlimbs. Therefore, the results confirmed the pattern already observed for most lizards. The novel element in our study is the detection of the relationship between a tendency towards caudal autotomy and digit ratio. Individuals with a tendency towards autotomy have a higher 2D:4D ratio in the right forelimbs and a lower 2D:3D ratio in the right hindlimbs. Obtained results suggest that these morphological characteristics are most likely related to intraspecific differences (between bold and shy individuals) which consequently may determine an individual's reaction or susceptibility to be a prey and escape behaviour. Thus, our results are probably the first attempt to link digit ratio to the susceptibility of lizards to tail autotomy.
- MeSH
- Biological Evolution MeSH
- Species Specificity MeSH
- Lizards anatomy & histology physiology MeSH
- Tail physiology MeSH
- Sex Characteristics MeSH
- Forelimb anatomy & histology MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Among spiders, taxonomically the most diversified group of terrestrial predators, only a few species are stenophagous and feed on ants. The levels of stenophagy and ant-specialisation vary among such species. To investigate whether stenophagy is only a result of a local specialisation both fundamental and realised trophic niches need to be estimated. Here we investigated trophic niches in three closely-related spider species from the family Gnaphosidae (Callilepis nocturna, C. schuszteri, Nomisia exornata) with different levels of myrmecophagy. Acceptance experiments were used to estimate fundamental trophic niches and molecular methods to estimate realised trophic niches. For the latter two PCR primer sets were used as these can affect the niche breadth estimates. The general invertebrate ZBJ primers were not appropriate for detecting ant DNA as they revealed very few prey types, therefore ant-specific primers were used. The cut-off threshold for erroneous MOTUs was identified as 0.005% of the total number of valid sequences, at individual predator level it was 0.05%. The fundamental trophic niche of Callilepis species included mainly ants, while that of N. exornata included many different prey types. The realised trophic niche in Callilepis species was similar to its fundamental niche but in N. exornata the fundamental niche was wider than realised niche. The results show that Callilepis species are ant-eating (specialised) stenophagous predators, catching mainly Formicinae ants, while N. exornata is an ant-eating euryphagous predator catching mainly Myrmicinae ants.
- MeSH
- DNA chemistry metabolism MeSH
- Ants genetics MeSH
- Spiders genetics physiology MeSH
- Polymerase Chain Reaction MeSH
- Predatory Behavior MeSH
- Cluster Analysis MeSH
- Body Size MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
In aquatic systems, chemical cues are one of the major sources of information through which animals can assess local predation risk. Non-native red-eared sliders (Trachemys scripta elegans) have the potential to disrupt aquatic ecosystems in Central Europe because of their superior competitive abilities and omnivorous diets. In this study, we examined whether continuous predator-borne cues are tied to changes in the developmental rates, growth rates and sizes at metamorphosis of common frog tadpoles (Rana temporaria). Our results show rather rarely documented types of amphibian prey responses to caged predators. The presence of turtles shortened the time at metamorphosis of tadpoles from 110 ± 11.7 days to 93 ± 13.0 days (mean ± S.D.). The first metamorphosed individuals were recorded on the 65th day and on the 80th day from hatching in the predator treatment and in the control group, respectively. The froglets were significantly smaller (12.8 ± 0.99 mm) in the presence of the predator than in the control treatment (15.2 ± 1.27 mm). The growth rate trajectories were similar between the predator treatment and the control. Thus, predator-induced tadpole defences were evident in higher developmental rates and smaller sizes at metamorphosis without significant changes in growth.
- MeSH
- Biological Evolution MeSH
- Metamorphosis, Biological * MeSH
- Ecosystem MeSH
- Cues * MeSH
- Predatory Behavior * MeSH
- Anura physiology MeSH
- Turtles physiology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
