Free-living Stages Research Articles

Parasites as prey: the effect of cercarial density and alternative prey on consumption of cercariae by four non-host species.

In parasites with complex life cycles the transmission of free-living infective stages can be influenced by ambient community diversity, in particular via predation. Here, we experimentally investigated whether parasite density and the presence of alternative prey can alter predation rates on free-living cercarial stages of a marine trematode by several non-host predators. All four predator species consumed increasing numbers of cercariae with an increase in cercarial density, indicating that the removal of cercariae by predators is effective over a range of natural densities as well as in the presence of alternative prey for a number of predators typical of marine ecosystems. However, the relative removal rates and the effects of cercarial density and alternative prey differed among predator species. In barnacles and shrimps, significant interactive effects of cercarial density and alternative prey on cercarial predation occurred while in oysters and crabs cercarial removal rates were unaffected by both factors. As changes in cercarial densities directly translate into changes in infection levels in down-stream hosts in this parasite-host system, the observed predator-specific responses suggest that cercarial predation effects on disease risks will depend on the specific species composition of ambient communities and not on non-host biodiversity per se.

Antiprotozoal effects of metal nanoparticles againstIchthyophthirius multifiliis

Ichthyophthirius multifiliis is a widespread, ciliated protozoan ectoparasite of fish. In the present study, we investigated the effects of metal nanoparticles on the reproduction and infectivity of free-living stages of I. multifiliis. We determined that ~50% of theronts could be killed within 30 min of exposure to either 20 ng mL-1 gold, 10 ng mL-1 silver or 5 ng mL-1 zinc oxide nanoparticles. Silver and zinc oxide nanoparticles at concentration of 10 and 5 ng mL-1 killed 100 and 97% of theronts, respectively and inhibited reproduction of tomonts after 2 h exposure. Gold nanoparticles at 20 ng mL killed 80 and 78% of tomonts and theronts 2 h post exposure, respectively. In vivo exposure studies using rainbow trout (Oncoryhnchus mykiss) demonstrated that theronts, which survived zinc oxide nanoparticles exposure, showed reduced infectivity compared with control theronts. No mortalities were recorded in the fish groups cohabited with theronts exposed to either nanoparticles compared with 100% mortality in the control group. On the basis of the results obtained from this study, metal nanoparticles particularly silver nanoparticles hold the best promise for the development of effective antiprotozoal agents useful in the management of ichthyophthiriosis in aquaculture.

Anthelmintic effects of forage chicory (Cichorium intybus) against free-living and parasitic stages of Cooperia oncophora

Chicory shows great promise as an anthelmintic forage for grazing ruminants that can reduce reliance on anti-parasitic drugs. Recently, we reported potent anthelmintic effects of chicory-based diets in infected cattle with significant reductions in worm burdens of the abomasal nematode Ostertagia ostertagi, whilst no apparent activity was observed against the small intestinal parasite Cooperia oncophora. To explore this discrepancy, we investigated direct anthelmintic effects of forage chicory against C. oncophora in vitro. Chicory leaves (cultivar ‘Spadona’) were extracted with methanol in a Soxhlet apparatus and the resulting extract was purified by solid-phase extraction to concentrate bioactive phytochemicals such as sesquiterpene lactones. C. oncophora eggs and adult worms from mono-infected donor calves were exposed to decreasing concentrations of the chicory extract. In an egg hatch assay, the chicory extract induced a marked and dose-dependent inhibition of egg hatching, with 95% inhibition at 2500μg extract/mL (EC50=619 [95% CI: 530–722] μg extract/mL). In the adult motility inhibition assays, the chicory extract induced a potent and dose-dependent worm paralysis. At 12h of incubation, worms exposed to chicory showed a total paralysis at ≥500μg extract/mL, while after 48h of incubation a complete inhibition of worm motility was observed at ≥250μg extract/mL (EC50=80 [95% CI: 67–95] μg extract/mL). We have demonstrated that forage chicory can induce potent inhibitory effects on the egg hatching and exert direct anthelmintic activity against parasitic stages of C. oncophora. These results suggest that the previously reported absence of in vivo effects of chicory towards C. oncophora in infected animals may be related with host-mediated factors and/or inhibitory digestive conditions, rather than an inherent inactivity of chicory and its bioactive phytochemicals.

Effects of commonly used chemical fertilizers on development of free-living stages of Haemonchus contortus in experimentally infected pasture.

Aim:The effects of N-P-K fertilizers in the form of urea, single super phosphate and muriate of potash on development of free-living stages of Haemonchus contortus were studied.Materials and Methods:Five parasite free experimental plots of 1 m×1 m area, each of paddy leaves (15-day-old) and an equal number of Cynodon dactylon grass were infested with about 10×104 eggs/ml phosphate buffer saline along with the application of the calculated amount of fertilizers solution. On the 10th day of posttreatment, the pasture was cut, processed, larvae recovered by Baermann method and counted, which was expressed as number of L3 per kg dry matter (DM) of pasture.Results:The average recovered population of L3 of H. contortus per kg DM varied significantly (p<0.05) between the paddy leaves (5933.57±22.718) and Cynodon grass (4861.00±22.718). When different doses of chemical fertilizer and their impact on different pasture were analyzed for control (T-1, 0-0-0 kg/ha N-P-K), the mean L3 recovery per kg DM of paddy (19512.7±50.80) was more than that of Cynodon grass (16540.9±50.80). Larvae recovery per kg DM for different pastures under treatment were in decreasing order as follows: T-2 of paddy (6981.33±50.80, 35.77%), T-2 of Cynodon (5545.38±50.80, 33.52%), T-3 of paddy (317378±50.80, 16.26%), and T-3 of Cynodon (2218.72±50.80, 13.41%) which showed significant difference (p<0.05) among the treatments. In T-4 (paddy) and T-5 (Cynodon), the average number of recovery of larvae was nil implying no significant variation (p>0.05).Conclusion:This study shown that when N-P-K fertilizers administered at recommended level, significantly reduced larval translation of H. contortus minimizing pasture infectivity for the free range grazing animals.

Antileishmanial activity and tubulin polymerization inhibition of podophyllotoxin derivatives on Leishmania infantum

Leishmania microtubules play an important role not only in cell division, but also in keeping the shape of the parasite and motility of its free-living stages. Microtubules result from the self-assembly of alpha and beta tubulins, two phylogenetically conserved and very abundant eukaryotic proteins in kinetoplastids. The colchicine binding domain has inspired the discovery and development of several drugs currently in clinical use against parasites. However, this domain is less conserved in kinetoplastids and may be selectively targeted by new compounds. This report shows the antileishmanial effect of several series of compounds (53), derived from podophyllotoxin (a natural cyclolignan isolated from rhizomes of Podophyllum spp.) and podophyllic aldehyde, on a transgenic, fluorescence-emitting strain of Leishmania infantum. These compounds were tested on both promastigotes and amastigote-infected mouse splenocytes, and in mammalian – mouse non-infected splenocytes and liver HepG2 cells – in order to determine selective indexes of the drugs. Results obtained with podophyllotoxin derivatives showed that the hydroxyl group at position C-7α was a structural requisite to kill the parasites. On regards podophyllic aldehyde, derivatives with C9-aldehyde group integrated into a bicyclic heterostructure displayed more potent antileishmanial effects and were relatively safe for host cells. Docking studies of podophyllotoxin and podophyllic aldehyde derivatives showed that these compounds share a similar pattern of interaction at the colchicine site of Leishmania tubulin, thus pointing to a common mechanism of action. However, the results obtained suggested that despite tubulin is a remarkable target against leishmaniasis, there is a poor correlation between inhibition of tubulin polymerization and antileishmanial effect of many of the compounds tested, fact that points to alternative pathways to kill the parasites.

Fatty acid composition of free-living and parasitic stages of the bovine lungworm Dictyocaulus viviparus

The development of parasitic nematodes proceeds via multiple stages, often implicating the necessity to adapt to different environments. Especially the transition from free-living to parasitic stages is accompanied by a significant change in the environmental conditions. To shed light on possible adaptations to these transitions, the fatty acid composition of different developmental stages of the bovine lungworm Dictyocaulus viviparus was investigated. Fatty acids of D. viviparus eggs, the free-living first, second and third larval stage (L1–L3) as well as the parasitic preadult stage and adult male and female worms residing in the lungs of infected hosts were quantified by gas chromatography after transesterification to their fatty acid methyl esters. The fatty acid content and diversity were higher in parasitic stages compared to those of free-living larvae. The most prevalent fatty acids in both parasitic and free-living stages were stearic (C18:0), palmitic (C16:0), palmitoleic (C16:1) and caprylic acid (C8:0). A variety of (poly-)unsaturated FAs was found in the parasitic stages and in the eggs, which was similar to the variety of FAs found in bovine surfactant. This finding indicates that parasitic stages of D. viviparus take up FAs from their environment. While eggs contained the highest concentration of fatty acids, a decrease was observed from eggs to L1 and further from L2 to L3. The lowest concentration was found in 38-days-old L3, which suggests that FAs serve as an energy reserve for the free-living, non-feeding larval stages. The free-living larvae contained mainly saturated fatty acids and only traces of unsaturated fatty acids, which is in contrast to the phospholipid saturation hypothesis of cold tolerance. Instead, a trade-off between desiccation stress and temperature adaptation may favour a higher amount of saturated FAs in the free-living larval stages. Further studies explicitly examining the FA composition of the different classes of lipids are necessary to better describe the adaptative responses of the FA metabolism to different environmental conditions.

Effects of road salt on larval amphibian susceptibility to parasitism through behavior and immunocompetence

Large quantities of road salts are used for de-icing in temperate climates but often leach into aquatic ecosystems where they can cause harm to inhabitants, including reduced growth and survival. However, the implications of road salt exposure for aquatic animal susceptibility to pathogens and parasites have not yet been examined even though infectious diseases can significantly contribute to wildlife population declines. Through a field survey, we found a range of NaCl concentrations (50–560mg/L) in ponds known to contain larval amphibians, with lower levels found in sites close to gravel- rather than hard-surfaced roads. We then investigated how chronic exposure to environmentally-realistic levels of road salt (up to 1140mg/L) affected susceptibility to infection by trematode parasites (helminths) in larval stages of two amphibian species (Lithobates sylvaticus − wood frogs, and L. pipiens − northern leopard frogs) by considering effects on host anti-parasite behavior and white blood cell profiles. Wood frogs exposed to road salt had higher parasite loads, and also exhibited reduced anti-parasite behavior in these conditions. In contrast, infection intensity in northern leopard frogs had a non-monotonic response to road salts even though lymphocytes were only elevated at the highest concentration. Our results indicate the potential for chronic road salt exposure to affect larval amphibian susceptibility to pathogenic parasites through alterations of behavior and immunocompetence, with further studies needed at higher concentrations, as well as that of road salts on free-living parasite infectious stages.

The genomic basis of nematode parasitism.

Nematodes are highly abundant animals, and many species have a parasitic lifestyle. Nematode parasites are important pathogens of humans and other animals, and there is considerable interest in understanding their molecular and genomic adaptations to nematode parasitism. This has been approached in three main ways: comparing the genomes of closely related parasitic and free-living taxa, comparing the gene expression of parasitic and free-living life cycle stages of parasitic nematode species, and analysing the molecules that parasitic nematodes excrete and secrete. To date, these studies show that many species of parasitic nematodes have genomes that have large gene families coding for proteases/peptidases, protease inhibitors, SCP/TAPS proteins and acetylcholinesterases, and in many cases there is evidence that these appear to be used by parasitic stages inside hosts, and are often secreted. Many parasitic nematodes have taxa-restricted gene families that also appear to be involved in parasitism, emphasizing that there is still much to be discovered about what it takes to be a parasitic nematode.

A novel framework to account for ecological drivers in the control and elimination of environmentally transmitted disease: a modelling study

BackgroundPopular fears about human infectious disease often focus on pathogens spread by person-to-person contact. By contrast, we show that 70–80% of human pathogens are environmentally transmitted (ie, people are infected through contact with free-living stages or environmental reservoirs including soil, water, vectors, food, or non- human hosts in the environment). In fact, environmentally transmitted diseases represent about 40% of today's global burden of human infectious disease (or 150 million disability adjusted life-years). Here, we call for renewed attention to the connection between human health and environmental factors, with a focus on identifying ecological solutions to interrupt transmission. MethodsWe developed a simple modelling framework that is able to capture the two main transmission pathways—namely, direct (host-to-host transmission, such in the case of influenza and measles) and transmission through an environmental reservoir (such, in the case of cholera, vector borne diseases, helminthiasis and sapronosis). We used the epidemiological model to analyse the role of ecological drivers for environmentally transmitted parasites and pathogens and to investigate the effectiveness of drug treatment for both directly and environmentally transmitted diseases. FindingsThrough the analysis of system dynamics, we show that periodic drug treatments that lead to the elimination of directly transmitted diseases might fail to do so in the case of human pathogens with an environmental reservoir. For environmentally transmitted diseases, more effective control can be achieved when classic treatment strategies are complemented with interventions that act on the environmental reservoir of the pathogen or reduce exposure. InterpretationControl of environmentally transmitted diseases can be more effective when human treatment is complemented with interventions targeting the environmental reservoir of the pathogen. Wherever environmental approaches to reduce human disease and preserve ecosystems are available, health practitioners, environmental scientists, and communities can work synergistically to solve health problems. FundingNational Science Foundation, Bill and Melinda Gates Foundation, NIMBioS, SNAP-NCEAS, Stanford FSI-SEED-GDP.

Global stability and Hopf bifurcation of a host–parasite system

Understanding the dynamical mechanism of the host–parasite interactions is one of important issues on host–parasite association. In this paper, we formulate a three-dimensional host–macroparasite system to describe the host–parasite interactions, which includes the logistic growth rate of host population, the important free-living stage and the host fecundity reduction due to parasite infection. The purpose of the paper is to investigate the asymptotical behavior of the system. By using the properties of the solution to non-autonomous linear system, the basic production number [Formula: see text] is proved to be a threshold which determines the outcome of the parasites. If [Formula: see text], the parasite will eventually die out, and if [Formula: see text] the parasite will be uniformly persistent. Hopf bifurcation of the system is further studied, and sufficient conditions for the Hopf bifurcation are obtained. By using the singular perturbation techniques, the system is separated into two time scales with a faster time scale for the free-living infective particles and a slower time scale for the population dynamics of host and parasite, and then a complete analysis of the dynamics on the slow manifold is conducted. The theoretical results show that the level of aggregation of parasites within host may influence the persistence and stability of the system.

Endozoicomonas genomes reveal functional adaptation and plasticity in bacterial strains symbiotically associated with diverse marine hosts

Endozoicomonas bacteria are globally distributed and often abundantly associated with diverse marine hosts including reef-building corals, yet their function remains unknown. In this study we generated novel Endozoicomonas genomes from single cells and metagenomes obtained directly from the corals Stylophora pistillata, Pocillopora verrucosa, and Acropora humilis. We then compared these culture-independent genomes to existing genomes of bacterial isolates acquired from a sponge, sea slug, and coral to examine the functional landscape of this enigmatic genus. Sequencing and analysis of single cells and metagenomes resulted in four novel genomes with 60–76% and 81–90% genome completeness, respectively. These data also confirmed that Endozoicomonas genomes are large and are not streamlined for an obligate endosymbiotic lifestyle, implying that they have free-living stages. All genomes show an enrichment of genes associated with carbon sugar transport and utilization and protein secretion, potentially indicating that Endozoicomonas contribute to the cycling of carbohydrates and the provision of proteins to their respective hosts. Importantly, besides these commonalities, the genomes showed evidence for differential functional specificity and diversification, including genes for the production of amino acids. Given this metabolic diversity of Endozoicomonas we propose that different genotypes play disparate roles and have diversified in concert with their hosts.

Does the dilution effect generally occur in animal diseases?

The dilution effect (DE) has been reported in many diseases, but its generality is still highly disputed. Most current criticisms of DE are related to animal diseases. Particularly, some critical studies argued that DE is less likely to occur in complex environments. Here our meta-analyses demonstrated that the magnitude of DE did not differ between animal vs plant diseases. Moreover, DE generally occurs in all three subgroups of animal diseases, namely direct-transmitted diseases, vector-borne diseases and diseases caused by parasites with free-living stages. Our findings serve as an important contribution to understanding the generality of DE.

Pulmonary Strongyloidiasis - A case report

Strongyloides stercoralis is an intestinal nematode with both free-living and parasitic stages and is common in the tropics. Chronic infection may lead to cutaneous, gastrointestinal, or pulmonary symptoms. We present the case of a 40-year-old male farmer, with on and off loose motions, productive cough, and loss of weight and was admitted with the provisional diagnosis of pulmonary tuberculosis. Rhabditiform larva of S. stercoralis was discovered in the sputum which was sent for screening of acid-fast bacilli. Stool examination was not done. There was no history suggestive of immunocompromised status and the screening test for HIV antibody was negative. Sputum culture showed growth of Escherichia coli. Other laboratory parameters were within normal limits. His chest X-ray revealed bilateral diffuse infiltrates. He was thereby diagnosed to be a case of pulmonary strongyloidiasis, but his condition deteriorated, and he expired before institution of any treatment. Although a potentially lethal opportunistic infection, strongyloidiasis is amenable to treatment with anthelmintics if detected in time. Hence, clinical suspicion with timely diagnosis and aggressive treatment becomes mandatory.

Seasonal and Spatial Environmental Influence on Opisthorchis viverrini Intermediate Hosts, Abundance, and Distribution: Insights on Transmission Dynamics and Sustainable Control.

BackgroundOpisthorchis viverrini (Ov) is a complex-life-cycle trematode affecting 10 million people in SEA (Southeast Asia). Human infection occurs when infected cyprinid fish are consumed raw or undercooked. Ov requires three hosts and presents two free-living parasitic stages. As a consequence Ov transmission and infection in intermediate and human hosts are strongly mediated by environmental factors and understanding how environmental variability influences intermediate host abundance is critical. The objectives of this study were 1) to document water parameters, intermediate hosts abundance and infection spatio-temporal variation, 2) to assess their causal relationships and identify windows of transmission risk.Methodology/Principal FindingsFish and snails were collected monthly for one year at 12 sites in Lawa Lake, an Ov-endemic region of Khon Kaen Province in Northeast Thailand. Physicochemical water parameters [pH, temperature (Tp), dissolved oxygen (DO), Salinity, electrical conductivity (EC), total dissolved solid (TDS), nitrite nitrogen (NO2-N), lead (Pb), total coliform bacteria (TCB) and fecal coliform bacteria (FCB)] were measured. Multivariate analyses, linear models and kriging were used to characterize water parameter variation and its influence on host abundance and infection prevalence. We found that sampling sites could be grouped in three clusters and discriminated along a nitrogen-salinity gradient where higher levels in the lake’s southern region predicted higher Bithynia relative abundance (P<0.05) and lower snail and fish species diversity (P<0.05). Highest Bithynia abundance occurred during rainy season (P<0.001), independently of site influence. Cyprinids were the most abundant fish family and higher cyprinid relative abundance was found in areas with higher Bithynia relative abundance (P<0.05). Ov infection in snails was anecdotal while Ov infection in fish was higher in the southern region (P<0.001) at sites showing high FCB.Conclusions/SignificanceOur results indicate that water contamination and waterways configuration can influence freshwater communities’ assemblages possibly creating ideal conditions for sustained transmission. Sustainable control may require a better appreciation of the system’s ecology with wise governance and development planning particularly in the current context of SEA agricultural intensification and landscape modification.

Implications of between-isolate variation for climate change impact modelling of Haemonchus contortus populations

The impact of climate change on parasites and parasitic diseases is a growing concern and numerous empirical and mechanistic models have been developed to predict climate-driven spatial and temporal changes in the distribution of parasites and disease risk. Variation in parasite phenotype and life-history traits between isolates could undermine the application of such models at broad spatial scales. Seasonal variation in the transmission of the haematophagous gastrointestinal nematode Haemonchus contortus, one of the most pathogenic helminth species infecting sheep and goats worldwide, is primarily determined by the impact of environmental conditions on the free-living stages. To evaluate variability in the development success and mortality of the free-living stages of H. contortus and the impact of this variability on future climate impact modelling, three isolates of diverse origin were cultured at a range of temperatures between 15°C and 37°C to determine their development success compared with simulations using the GLOWORM-FL H. contortus model. No significant difference was observed in the developmental success of the three isolates of H. contortus tested, nor between isolates and model simulations. However, development success of all isolates at 37°C was lower than predicted by the model, suggesting the potential for overestimation of transmission risk at higher temperatures, such as those predicted under some scenarios of climate change. Recommendations are made for future climate impact modelling of gastrointestinal nematodes.

Allegory of a cave crustacean: systematic and biogeographic reality of Halosbaena (Peracarida: Thermosbaenacea) sought with molecular data at multiple scales

Halosbaena Stock, 1976 are small crustaceans found in a number of distant, isolated subterranean locations in the Northern (Caribbean and Canary Islands) and Southern Hemispheres (Christmas Island and north-western Australia in Cape Range, Barrow Island and Pilbara regions). This distribution is surprising for an animal that produces few eggs, has no free-living larval stage, and succours their young in a dorsal brood pouch. It is usually explained by the passive movement of ancestral populations on tectonic plates as the ancient Tethys Ocean spread. We used molecular data (one mitochondrial and three nuclear genes) to reconstruct phylogenies and time-trees to understand their biogeography at the global scale and at four diminishing scales within the Southern Hemisphere. We found: (1) a basal split between species in the Northern and Southern Hemispheres, but the inferred ages of divergences between species are not old enough to be associated with the spread of the Tethys; (2) a recently discovered species from Christmas Island which is the sister to Australian mainland taxa; (3) the one described species from mainland Australia, H. tulki, probably constitutes at least five separate species that reflect local geography (Cape Range west, Cape Range east, Barrow Island, Pilbara low elevation, Pilbara high elevation); (4) the Pilbara high elevation taxon is likely not old enough to have been stranded high inland during an Eocene marine transgression; and (5) phylogeographic breaks within Cape Range west are congruent with other breaks in sympatric cave species.

The genome of Strongyloides spp. gives insights into protein families with a putative role in nematode parasitism.

Parasitic nematodes are important and abundant parasites adapted to live a parasitic lifestyle, with these adaptations all aimed at facilitating their survival and reproduction in their hosts. The recently sequenced genomes of four Strongyloides species, gastrointestinal parasites of humans and other animals, alongside transcriptomic and proteomic analysis of free-living and parasitic stages of their life cycles have revealed a number of protein families with a putative role in their parasitism. Many of these protein families have also been associated with parasitism in other parasitic nematode species, suggesting that these proteins may play a fundamental role in nematode parasitism more generally. Here, we review key protein families that have a putative role in Strongyloides' parasitism - acetylcholinesterases, astacins, aspartic proteases, prolyl oligopeptidases, proteinase inhibitors (trypsin inhibitors and cystatins), SCP/TAPS and transthyretin-like proteins - and the evidence for their key, yet diverse, roles in the parasitic lifestyle.

Size-dependent predation alters interactions between parasites and predators

Increasing evidence indicates that parasites play an important role within many systems as prey for higher trophic levels. Predation on parasites can decrease their numbers and may affect host infection rates. Cercariae, a free-living infectious stage of trematode parasites, are abundant in freshwater systems and are directly consumed by a number of freshwater predators. However, few studies have tested whether predators exhibit a preference for cercariae when alternative prey are available or how these preferences vary across predator body sizes. We assessed whether dragonfly larvae (dot-tailed whiteface, Leucorrhinia intacta (Hagen, 1861)), top predators in freshwater systems without fish, foraged preferentially when presented with two prey types, cercariae and zooplankton, and whether foraging preferences changed across predator body size. Body size of larval dragonfly predators was found to be significantly, and negatively, related to the fraction of cercariae in the diet. Larger bodied dragonfly larvae shifted their diet choice from cercariae to zooplankton. Changes in foraging selectivity as body size increases across a predator’s ontogeny can alter the strength of predator–prey interactions. Further investigation into size-selective foraging on parasites may provide new insights into the effects of predation on parasite abundance and transmission in natural systems.

Influence of water infusion of medicinal plants on larvae of Strongyloides papillosus (Nematoda, Strongyloididae)

One of the most common nematodes of ruminants is Strongyloides papillosus (Wedl, 1856). Disease caused by these parasites brings economic losses to livestock operations. Therefore it is necessary to control their numbers. The eggs and three larval stages of S. papillosus live in the environment, while the fourth, fifth and mature individuals live in host organisms. Control of these parasites is necessary at all stages of development, including the free-living stage. An experiment on changes in the number strongiloids under the influence of environmental factors was carried out using aqueous extracts of medicinal plants. In the laboratory experiment we researched the effect on the survival of invasive and noninvasive types of S. papillosus larvae of 24 hours exposure at different doses to Artemisia absinthium Linnaeus, 1753, Artemisia annua Linnaeus, 1753, Echinacea purpurea (Linnaeus, 1753) Moench, 1794, Matricaria chamomilla Linnaeus, 1753, Tanacetum vulgare Linnaeus, 1753, Salvia sclarea Linnaeus, 1753, Levisticum officinale W.D.J. Koch, 1824, Petroselinum crispum (Miller, 1768) Nyman ex A.W. Hill, 1925. The death of 50% of S. papillosus invasive larvae was registered at 464 ± 192 mg/l concentration of aqueous extract of S. sclarea inflorescences. The greatest effect up-on the non-invasive larvae was caused by aqueous extracts of inflorescences of S. sclarea, M. chamomilla and seeds of P. crispum: at concentrations of 327 ± 186, 384 ± 155 and 935 ± 218 mg/l, respectively, 50% of non-invasive larvae died. According to the results of the research, we suggest further study of the nematocidal activity of combinations, contained in the aboveground parts, of clary sage (S. sclarea), camomile (M. chamomilla) and seeds of parsley (P. crispum), and also experimental usage of these species in the fodder compound for cattle, sheep, goats and pigs on experimental farms.

Diversity and function of prevalent symbiotic marine bacteria in the genus Endozoicomonas.

Endozoicomonas bacteria are emerging as extremely diverse and flexible symbionts of numerous marine hosts inhabiting oceans worldwide. Their hosts range from simple invertebrate species, such as sponges and corals, to complex vertebrates, such as fish. Although widely distributed, the functional role of Endozoicomonas within their host microenvironment is not well understood. In this review, we provide a summary of the currently recognized hosts of Endozoicomonas and their global distribution. Next, the potential functional roles of Endozoicomonas, particularly in light of recent microscopic, genomic, and genetic analyses, are discussed. These analyses suggest that Endozoicomonas typically reside in aggregates within host tissues, have a free-living stage due to their large genome sizes, show signs of host and local adaptation, participate in host-associated protein and carbohydrate transport and cycling, and harbour a high degree of genomic plasticity due to the large proportion of transposable elements residing in their genomes. This review will finish with a discussion on the methodological tools currently employed to study Endozoicomonas and host interactions and review future avenues for studying complex host-microbial symbioses.