Natural Parasite Research Articles

HELMINTH DIVERSITY OF GREEN TREEFROGS (HYLA CINEREA) IN THEIR EXPANDED GEOGRAPHICAL RANGE.

There has been a growing interest in characterizing the parasite faunas of species populations as they expand their geographical ranges as a result of climate change. Expanded-range populations often exhibit lower parasite diversity than historical-range populations, and reduced parasitism may, in part, be attributable to expanded-range populations escaping their native range parasites. The present study compares the helminth faunas of green treefrogs (Hyla cinerea) from 4 historical and 4 expanded-range populations to determine whether these latter populations have undergone parasite escape. Results of this study found relatively high degrees of similarity in species composition among helminth assemblages within historical or within range-expansion locations, with marked differences in the composition of helminth faunas between historical and expanded-range populations of these frogs. Because green treefrogs from expanded-range locations exhibited significant decreases in helminth species diversity compared with those from historical sites, they appear to be escaping levels of parasitism typically experienced by these frogs in their native range. Most notably, there was a decrease in the abundance of helminths with direct life cycles and the absence of trematode assemblages with indirect life cycles among expanded-range populations of H. cinerea. The low prevalence of trematode assemblages among historical populations of green treefrogs could limit these parasites' ability to be introduced and propagated in expanded-range locations. However, the lack of trematode assemblages among populations of H. cinerea in its expanded range may also be due to the absence or limited availability of other aquatic hosts that are required to complete the life cycles of these parasites. The reduction in helminth diversity among expanded-range populations of green treefrogs lends some credence to the notion that individuals at the front of a range expansion often invest less energy in reproduction and in doing so allocate more energy to dispersal and other life-history traits, including resistance to parasites. There may, however, be other explanations for differences in parasite species diversity between historical and expanded-range populations of H. cinerea. Because many of the helminths reported from this study are host generalists of amphibians whose recruitment and transmission among intermediate and paratenic hosts are known to be constrained by water and/or soil moisture conditions, we cannot ignore the role of both local amphibian diversity and local abiotic factors in influencing helminth diversity between the 2 population types of green treefrogs. These latter factors would decrease the role of parasite escape or energy trade-offs in driving helminth diversity among populations of H. cinerea and instead would suggest that local conditions play a more prominent role in structuring their helminth communities.

Gregarines modulate insect responses to sublethal insecticide residues

Throughout their lifetime, insects face multiple environmental challenges that influence their performance. Gregarines are prevalent endoparasites in most invertebrates that affect the fitness of their hosts, but are often overlooked in ecological studies. Next to such biotic factors, a current common challenge is anthropogenic pollution with pesticides, which causes a major threat to non-target organisms that are readily exposed to lethal or sublethal concentrations. In a laboratory study, we investigated whether the presence of gregarines modulates the food consumption and life history traits of a (non-target) leaf beetle species, Phaedon cochleariae, in response to sublethal insecticide exposure. We show that the larval food consumption of the herbivore was neither affected by gregarine infection nor sublethal insecticide exposure. Nevertheless, infection with gregarines led to a delayed development, while insecticide exposure resulted in a lower body mass of adult males and a reduced reproduction of females. Individuals exposed to both challenges suffered most, as they had the lowest survival probability. This indicates detrimental effects on the population dynamics of non-target insects infected with naturally occurring gregarines that face additional stress from agrochemical pollution. Moreover, we found that the infection load with gregarines was higher in individuals exposed to sublethal insecticide concentrations compared to unexposed individuals. To counteract the global decline of insects, the potential of natural parasite infections in modulating insect responses to anthropogenic and non-anthropogenic environmental factors should be considered in ecological risk assessment.

Natural parasitization of Cotesia spp. and Bracon spp. on Spodoptera litura Fab. in castor crop

The larval stage of Spodoptera litura Fab. is more prone to parasitism. Larval parasitoids such as braconids belongs to family Braconidae of order Hymenoptera acts as Ecto parasitoids. Braconids have wide host range and successful biocontrol agent recommended for the control of lepidopteran larvae in many crops and stored grains. The present study on parasitization of braconids on S. litura was conducted under laboratory conditions. The larva of S. litura collected from castor crop from various locations near by Nagpur, Maharashtra, India and reared on castor leaves under laboratory conditions. The larvae were parasitized by two parasitoids namely, Cotesia spp. and Bracon spp. The study revealed that the field collected larva of S. litura when reared on castor leaves showed an average parasitization of 11% and 4.3% by Cotesia spp. and Bracon spp. respectively.

Changes in the Serum Protein Fractions in Goats after Treatment of Natural Gastrointestinal Parasite Infections.

Gastrointestinal parasitic infections in small ruminants belong to major health problems. The regulation of gastrointestinal infections in goats and the responses developed against them appear to be different from those observed in sheep. In the literature, there is a lack of data on the effect of gastrointestinal parasitic infections on the serum protein profile in goats. Therefore, the aim of the study was to determine the electrophoretic pattern of serum proteins in goats naturally infected with gastrointestinal parasites and to compare the changes in the total serum proteins and serum protein fractions (albumin and α1-, α2-, β-, and γ-globulins) obtained after antihelminthic treatment. Eight adult female goats of the white shorthaired breed from a small dairy goat farm at the age ranging between 3 and 5 years with average body weight 35.4 ± 3.2 kg and body condition score (BCS) from 1.5 to 2.5 were used in the study. The serum proteins in goats were separated into five fractions: albumin, α1- and α2-globulins, and β- and γ-globulins. Significant changes after treatment were found in the relative concentrations of albumin (P < 0.01) and α2- (P < 0.05), β- (P < 0.001), and γ-globulins (P < 0.01), as well as albumin/globulin ratio (P < 0.01). The mean concentration of total serum proteins was, after the antiparasitic treatment, significantly higher. Among the globulin fractions, the γ-globulin fraction contributed most significantly to these changes (P < 0.001). The results presented in the study suggest a significant effect of antiparasitic treatment in goats on the synthesis of blood serum proteins and on the changes of the proportion of serum protein fractions.

Pregnant dairy goats endoparasites reduced by commercial Homeopathy

Background: the endoparasitosis affects dairy goats in worldwide distribution. This impacts the economical activity and implies in eminent risk of animal looses by helminths blood depletion (Nogueira, 2010). Resistance to all therapeutic drugs is reported, the parasitism implies to elevation of production costs, toxic residues in milk and environment, frequently monitoring of ocular mucosa and healthy status (Cavalcanti, 2007; Silva, 2010). Many publications reports Fecal Eggs Count (FEC) FEC reduction in sheeps with homeopathy (Chagas, 2008; Zacharias 2008; Neves, 2012; Falbo, 2013). This work continues the study of previous assessment with young females caprines, but now during the breeding season and multipara pregnants. The under field conditions intends to address the value of this complex medicine in the real life situation of a caprinoculture routine and the animal zootechnical production phases. Aims: this work determined the parasite load by FEC during the periods of breeding season and pregnancy of dairy goats with commercial populational homeopathy. Methodology: Fifteen (15) adult multipara goats (CAPRA AERGICUS HIRCUS) aged 4.4 ± 1.4 years old were randomly enrolled into two groups. The animals has dairy predominance of Alpine and Saanen breeds and were fed by maize and sugar cane silage. Routine measures to reduce the natural parasitism infection included keeping them in elevated houses with slatted floor with access to paddock star grass with time restrictions to the hottest hours in the day. They received the albendazole antihelmintic drenching before each of the phases. The weekly FEC was performed in triplicate with the McMaster Egg Counting Chamber Technique and the optical microscope. The treatment with 10g-animal-day CapriOvi Verm 100 RealH (Brazil) was given daily among both phases, six times a week with individual oral administration, the powder was diluted (not sucussed) in a plastic cup with tap water and given in a 10mL syringe. The control group received only tap water in the same way but brand new separated set of disposable materials. Each phase had evaluating period of 10 and 11 weeks respectively. The first phase has the four weeks breeding season, previously stimulated by light program, with sex mating on the middle and the second phase the animals was pregnant for 2 to 4 months. Results: The FEC kept above 500 eggs during 7 weeks at the breeding season-1st phase but grew as expected in the pregnancy-2nd phase. The FEC was significantly reduced during the 2nd phase (p-value &lt; 0.01) but not in the breeding season-1st phase (p-value = 0.28), despite being lower than the control. The two-way ANOVA showed that treatment in the 2nd phase affected the results [F 1/143 = 9.04, p = 0.0031] as the time does [F 1/143 = 53.29, p &lt; 0.0001]: there were interactions between factors [F 1/143 = 3.15, p = 0.0011]. The two-way ANOVA showed that treatment in the 1nd phase affected the results [F 1/130 = 0.30, p = 0.58] as the time [F 1/130 = 1.24, p = 0.28]: there were no interactions between factors [F 1/130 = 0.58, p = 0.81]. Surprisingly there was absence of growing FEC in the breeding season, at this phase the dry goats and may have better immune response to the endoparasites than the stress of the pregnancy. Our group suppose the stressed animal model is more susceptible and may show better the effects of treatment reducing the FEC in a high challenge situation. How it influences the way of action of ultra high dilutions remains a very interesting question for guide future works. Conclusion: the populational homeopathy product CapriOvi Verm 100 RealH has shown the reduction of the FEC during the pregnancy of dairy goats.

Molecular Characterization of the Vairimorpha (Nosema) ceranae Infection from Bombus terrestris (Linnaeus, 1758) (Hymenoptera: Apidae) in Turkey

The current study aimed to determine the natural pathogen and parasites of the Bombus terrestris L. (Hymenoptera: Apidae) in Turkey. During 2019 and 2020, the commercial and wild populations of B. terrestris were investigated in this survey. In the studies, natural microsporidiosis was detected in commercial B. terrestris populations. Fresh oval spores were measured as 4.91 ± 0.48 (6.12 – 3.73) µm in length and 2.54 ± 0.31 (3.27 – 1.88) µm in width (n=60). Both SSU rRNA and RPB1 gene sequences of the current microsporidium were top hits with the Vairimorpha (Nosema) ceranae isolates. While the SSU rRNA gene sequence matched with the Vairimorpha ceranae clone NCS44 (LC510228) isolated from the Apis cerana japonica at 99.24% identity (100% coverage), the RPB1 gene sequence was matched with the Vairimorpha ceranae isolate 1994 (KJ473287) at 99.02% identity (100% coverage). Based on the light microscopy and molecular phylogeny the current microsporidium was a new isolate of the V. ceranae and named herein as Vairimorpha ceranae Tr-07.

Spread and phenology of Spathius galinae and Tetrastichus planipennisi, recently introduced for biocontrol of emerald ash borer (Coleoptera: Buprestidae) in the northeastern United States

Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive wood-boring pest of ash trees (Fraxinus spp.) in the United States. It is responsible for catastrophic decline of ash in urban and forested ecosystems, resulting in millions of dollars in economic losses. Biological control is one of the most promising management options available to reduce A. planipennis spread and impact. From 2015 to 2017, two larval parasitoids from the native range of A. planipennis, Spathius galinae Belokobylskij & Strazenac (Hymenoptera: Braconidae) and Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae), were released in forested areas in New York and Connecticut. The purpose of this study was to measure the spread and seasonal phenology of these introduced parasitoids. From May to September 2020, sentinel ash logs containing EAB larvae were deployed in naturally occurring A. planipennis infested trees at each release site and at 2 km intervals up to 14 km away from the release site. Logs were replaced every two weeks and the parasitization rate was recorded. Each month, three trees from each release area were also cut and debarked to record A. planipennis infestation levels, natural parasitization rates, and A. planipennis and parasitoid phenology. We observed that both S. galinae and T. planipennisi emerged from the logs first deployed from the end of May to early June. Parasitization peaked in late July and mid-August, with sentinel logs deployed at each distance producing both species throughout the summer until mid-September. Both S. galinae and T. planipennisi were detected 14 km away from the release sites, the greatest distance away from the release sites sampled. Debarked trees produced similar seasonal patterns of parasitism. Our results indicate that the classical biological control program initiated several years ago has successfully produced a self-sustaining population of both S. galinae and T. planipennisi, which have been spreading widely and attacking the borer throughout the growing season. These findings strongly suggest that future release efforts may allow for wider temporal release windows and larger strategic spacing of release points across geographic regions.

Malaria parasite liver stages

Malaria parasite liver stages

Trichoderma infection of limno-terrestrial tardigrades

Interactions between fungi and tardigrades have scarcely been described. The few studies that address such relationships suggest a primarily parasitic nature for various fungal taxa, including the infectious chytridiomycetes. The aim of this study was to determine the identity of a fungus growing on a tardigrade of the genus Diaforobiotus and if it could infect other tardigrade genera. Using morphological analysis and ITS barcoding, we identified a mold isolate belonging to the Trichoderma harzianum species complex and found that it infected Diaforobiotus tardigrades, as well as animals in the eutardigrade genus Milnesium, and heterotardigrade genus Viridiscus.

Differential effects of elevated nest temperature and parasitism on the gut microbiota of wild avian hosts

BackgroundChanges in wild animal gut microbiotas may influence host health and fitness. While many studies have shown correlations between gut microbiota structure and external factors, few studies demonstrate causal links between environmental variables and microbiota shifts. Here, we use a fully factorial experiment to test the effects of elevated ambient temperature and natural nest parasitism by nest flies (Protocalliphora sialia) on the gut microbiotas of two species of wild birds, the eastern bluebird (Sialia sialis) and the tree swallow (Tachycineta bicolor).ResultsWe find that bacterial communities from the nestlings of each host species show idiosyncratic responses to both heat and parasitism, with gut microbiotas of eastern bluebirds more disrupted by heat and parasitism than those of tree swallows. Thus, we find that eastern bluebirds are unable to maintain stable associations with their gut bacteria in the face of both elevated temperature and parasitism. In contrast, tree swallow gut microbiotas are not significantly impacted by either heat or nest parasitism.ConclusionsOur results suggest that excess heat (e.g., as a result of climate change) may destabilize natural host-parasite-microbiota systems, with the potential to affect host fitness and survival in the Anthropocene.

Does phosphorus influence performance of a native hemiparasite and its impact on a native legume?

Phosphorus (P) is an essential plant nutrient and can become limiting in terrestrial ecosystems where parasitic plant:host associations occur. Yet little is known on how P availability influences parasite performance and its impact on hosts. We investigated the performance of the Australian native stem hemiparasite Cassytha pubescens and its impact on the native leguminous shrub Acacia paradoxa in high or low P conditions in a glasshouse experiment. Infected plants had significantly lower total, shoot, root and nodule biomass and shoot:root ratio than uninfected plants, regardless of P supply. The significant negative effect of infection on arbuscular mycorrhizal colonisation of host roots was more severe in the high P treatment. Infection significantly decreased predawn quantum yield of A. paradoxa in low P but not high P conditions. This finding may be due to the parasite-induced significant enrichment of aluminium in host foliage in low P but not high P treatments. A. paradoxa had significantly lower foliar phosphorus concentration [P] and nitrogen concentration in low P than high P conditions. Parasite biomass and photosynthetic performance were unaffected by P, whereas C. pubescens had significantly lower stem [P] in the low P than high P treatment. Parasite carbon isotope composition was significantly higher than that of the host, especially in low P conditions. Our results show that: (a) native parasite growth and its negative impact on growth of this native shrub was unaffected by P supply and (b) soil P conditions may have no influence on stem hemiparasite:host associations in nature.

The First Survey for Helminths Parasitic in Hybrid and Introduced Giant Salamanders, Genus Andrias (Amphibia: Caudata: Cryptobranchidae) in Kyoto, Japan

The first survey was conducted for helminth fauna of hybrid giant salamanders (hybrids between Andrias japonicus and other congeneric species), and introduced A. davidianus in Kyoto Prefecture, Japan. Three nematode species, Spiroxys hanzaki, Amphibiocapillaria tritonispunctati and Falcaustra sp., and one trematode species, Liolope copulans, were recovered from their alimentary canals. These results show that hybrid and introduced Andrias species are commonly infected with similar helminth species to those previously reported to infect A. japonicus. We conclude that the spillback of native parasites to introduced A. davidianus has occurred in Kyoto Prefecture. This study is also the first record of Falcaustra species parasitizing Andrias species in Japan.

Diagnostic accuracy of a novel enzyme-linked immunoassay for the detection of IgG and IgG4 against Strongyloides stercoralis based on the recombinant antigens NIE/SsIR

BackgroundThe diagnosis of strongyloidiasis is challenging. Serological tests are acknowledged to have high sensitivity, but issues due to cross-reactions with other parasites, native parasite antigen supply and intrinsic test variability do occur. Assays based on recombinant antigens could represent an improvement. The aim of this study was to assess the sensitivity and specificity of two novel immunoglobulin (Ig)G and IgG4 enzyme-linked immunosorbent assays (ELISAs) based on the recombinant antigens NIE/SsIR for the diagnosis of strongyloidiasis.MethodsThis was a retrospective diagnostic accuracy study. We included serum samples collected from immigrants from strongyloidiasis endemic areas for whom there was a matched result for Strongyloides stercoralis on agar plate culture and/or PCR assay, or a positive microscopy for S. stercoralis larvae. For the included samples, results were also available from an in-house indirect fluorescent antibody test (IFAT) and a commercial (Bordier ELISA; Bordier Affinity Products SA) ELISA. We excluded: (i) samples with insufficient serum volume; (ii) samples from patients treated with ivermectin in the previous 6 months; and (iii) sera from patients for whom only routine coproparasitology was performed after formol–ether concentration, if negative for S. stercoralis larvae. The performance of the novel assays was assessed against: (i) a primary reference standard, with samples classified as negative/positive on the basis of the results of fecal tests; (ii) a composite reference standard (CRS), which also considered patients to be positive who had concordant positive results for the IFAT and Bordier ELISA or with a single “high titer” positive result for the IFAT or Bordier ELISA. Samples with a single positive test, either for the IFAT or Bordier ELISA, at low titer, were considered to be “indeterminate,” and analyses were carried out with and without their inclusion.ResultsWhen assessed against the primary reference standard, the sensitivities of the IgG and IgG4 ELISAs were 92% (95% confidence interval [CI]: 88–97%) and 81% (95% CI: 74–87%), respectively, and the specificities were 91% (95% CI: 88–95%) and 94% (95% CI: 91–97%), respectively. When tested against the CRS, the IgG ELISA performed best, with 78% sensitivity (95% CI: 72–83%) and 98% specificity (95% CI: 96–100%), when a cut-off of 0.675 was applied and the indeterminate samples were excluded from the analysis.ConclusionThe NIE-SsIR IgG ELISA demonstrated better accuracy than the IgG4 assay and was deemed promising particularly for serosurveys in endemic areas.Graphical abstract

Honey Bee Habitat Sharing Enhances Gene Flow of the Parasite Nosema ceranae.

Host-parasite co-evolution is a process of reciprocal, adaptive genetic change. In natural conditions, parasites can shift to other host species, given both host and parasite genotypes allow this. Even though host-parasite co-evolution has been extensively studied both theoretically and empirically, few studies have focused on parasite gene flow between native and novel hosts. Nosema ceranae is a native parasite of the Asian honey bee Apis cerana, which infects epithelial cells of mid-guts. This parasite successfully switched to the European honey bee Apis mellifera, where high virulence has been reported. In this study, we used the parasite N. ceranae and both honey bee species as model organisms to study the impacts of two-host habitat sharing on parasite diversity and virulence. SNVs (Single Nucleotide Variants) were identified from parasites isolated from native and novel hosts from sympatric populations, as well as novel hosts from a parapatric population. Parasites isolated from native hosts showed the highest levels of polymorphism. By comparing the parasites isolated from novel hosts between sympatric and parapatric populations, habitat sharing with the native host significantly enhanced parasite diversity, suggesting there is continuing gene flow of parasites between the two host species in sympatric populations.

High Granulocyte-Macrophage Colony Stimulating Factor to Interleukin 10 Ratio and Marked Antioxidant Enzyme Activities Predominate in Symptomatic Cattle Naturally Infected with Candidatus Mycoplasma haemobos, Theileria orientalis, Theileria sinensis and Trypanosoma evansi.

Simple SummaryThe aim of this study was to evaluate the proinflammatory (interleukin 12, GM-CSF, interferon-γ) to anti-inflammatory (interleukins 10, 4) cytokine ratios, oxidant level (malondialdehyde) and antioxidant enzyme (superoxide dismutase, glutathione peroxidase) activities in sera from symptomatic and asymptomatic cattle infected with blood parasites relative to clinically healthy cattle. Elevations in serum GM-CSF level was recorded in both symptomatic and asymptomatic cattle infected with blood parasites. Cattle naturally infected with C. M. haemobos and T. orientalis but without clinical signs had anti-inflammatory cytokine immune responses characterized by low proinflammatory to anti-inflammatory cytokine ratios which favor parasite persistence and resistance in the host. Serum activities of antioxidant enzymes (superoxide dismutase and glutathione peroxidase) and malondialdehyde concentration were elevated in all the symptomatic and asymptomatic blood parasite infected cattle groups. Therefore, a high GM-CSF:IL10 response alongside marked antioxidative enzyme responses were predominant findings in cattle with clinical signs of natural blood parasite infections.The aim of this study was to measure the serum proinflammatory (IL-12, GM-CSF & IFN-γ) to anti-inflammatory (IL-10, IL-4) cytokine ratio, oxidant (MDA) level and antioxidant enzyme (SOD; GPx) activities after blood parasite infections. The blood and serum samples were obtained from 130 cattle and screened for identity of the infecting blood parasites by conventional PCR. The following blood parasite species were detected: Candidatus Mycoplasma haemobos (70/130); Theileria orientalis (65/130); Theileria sinensis (32/130); Anaplasma marginale (49/130); Anaplasma platys (7/130); and Trypanosoma evansi (4/130). The GM-CSF/IL-10 ratio showed significantly higher values in all the symptomatic blood parasite infected cattle groups except for symptomatic A. platys infected cattle groups. Anti-inflammatory cytokine immune responses were notable findings in symptomatic and asymptomatic cattle infected with C. M. haemobos and T. orientalis characterized by low serum IL-12:IL-10, IFN-γ:IL-10, IL-12:IL-4 and IFN-γ:IL-4 (p < 0.05). Therefore, high serum GM-CSF:IL:10 in the symptomatic blood parasite infected cattle, low serum IL-12:IL-10, IFN-γ:IL-10, IL-12:IL-4 and IFN-γ:IL-4 ratios in asymptomatic cattle, high MDA level, and increased antioxidant enzyme activities could be useful predictive tools for outcome of natural blood parasite infections in cattle.

Immune response of adult horses, pregnant mares and foals to an experimental vaccine with recombinant EMA-2 protein of Theileria equi

Equine theileriosis, caused by the Theileria equi protozoan, is a disease of worldwide importance. T. equi expresses surface proteins, of which the EMA-2 protein is a promising antigen for vaccine use. The aim of this study was to evaluate the immune response of adult horses, pregnant mares, and foals to an experimental EMA-2 protein of recombinant T. equi vaccine. A total of 46 horses were used in this study for vaccine trials and challenges. Twelve geldings, 14 pregnant mares, and 14 foals were divided into vaccinated and control groups. Total serum specific anti-rEMA-2 IgG, IgG subclasses, and transcription of cytokines related to the immune response were evaluated. For the vaccine challenge, six six-month-old foals were divided into vaccinated and control groups. For the challenge, blood from a horse with theileriosis was transfused to the foals. Geldings and pregnant mares maintained anti-rEMA-2 IgG levels at 130 and 140 days after vaccination, respectively. The most-detected IgG subclasses in vaccinated were IgG3/5, IgG4/7, and IgG1. IL2, IL10, IL12, IL17, IFN-γ, and TNF-α were the most-transcribed cytokines in PBMCs of vaccinated horses stimulated with rEMA-2. Challenge with T. equi demonstrated that vaccinated foals had an increase of 33% in total IgG four days after blood transfusion, while control foals had no significant response, suggesting that vaccine antibodies may have recognized EMA-2 protein of the native T. equi antigen. T. equi recombinant EMA-2 was shown to be a promising vaccine antigen by inducing humoral and cellular immunity similar to that observed in natural parasite infections.

Invasive oysters as new hosts for native shell-boring polychaetes: Using historical shell collections and recent field data to investigate parasite spillback in native mussels in the Dutch Wadden Sea

Biological invasions can have manifold effects on native biota, including impacts on species interactions in invaded ecosystems. Among those are effects on parasite-host interactions, for example in cases where invaders serve as a new host for native parasites, leading to an amplification of the parasite population which may ultimately result in increased infection levels in the original native hosts (parasite spillback). In this study, we investigated the potential spillback of the native shell-boring polychaete Polydora ciliata from invasive Pacific oysters (Crassostrea (Magallana) gigas) to native mussels (Mytilus edulis) in the Dutch Wadden Sea. A field survey in the intertidal revealed that the majority of P. ciliata can nowadays be found in the shells of live but also dead Pacific oysters and much less in shells of other potential host species: mussels and periwinkles (Littorina littorea). Using a unique historical shell collection based on long-term sampling programmes in the intertidal and subtidal of the western Dutch Wadden Sea, we compared P. ciliata infections in mussels before and after the invasion of the Pacific oyster by means of x-ray scans. Both for the intertidal and subtidal, we did not detect differences in prevalence of P. ciliata in mussels between pre- and post-invasion periods. This suggests that the invasion of the Pacific oyster may not have caused a strong spillback to mussels regarding P. ciliata and thus the invasion probably had little indirect infection-mediated effects on the condition and fitness of native mussels. Instead, the acquisition of native P. ciliata by the invasive oysters suggests that they may themselves be affected by the new infections and this may warrant further research.

Fitness of sulfadoxine-resistant Plasmodium berghei harboring a single mutation in dihydropteroate synthase (DHPS)

Genetic changes conferring drug resistance are generally believed to impose fitness costs to pathogens in the absence of the drug. However, the fitness of resistant parasites against sulfadoxine/pyrimethamine has been inconclusive in Plasmodium falciparum. This is because resistance is conferred by the complex combination of mutations in dihydropteroate synthase (dhps) and dihydrofolate reductase (dhfr), which makes it difficult to separately assess the extent and magnitude of the costs imposed by mutations in dhps and dhfr. To assess the fitness costs imposed by sulfadoxine resistance alone, we generated a transgenic rodent malaria parasite, P. berghei clone harboring an A394G mutation in dhps (PbDHPS-A394G), corresponding to the causative mutation for sulfadoxine resistance in P. falciparum (PfDHPS-A437G). A four-day suppressive test confirmed that the PbDHPS-A394G clone was resistant to sulfadoxine. PbDHPS-A394G and wild-type clones showed similar growth rates and gametocyte production. This observation was confirmed in competitive experiments in which PbDHPS-A394G and wild-type clones were co-infected into mice to directly assess the survival competition between them. In the mosquitoes, there were no significant differences in oocyst production between PbDHPS-A394G and wild-type. These results indicate that the PbDHPS-A394G mutation alters the parasites to sulfadoxine resistance but may not impose fitness disadvantages during the blood stages in mice and oocyst formation in mosquitoes. These results partly explain the persistence of the PfDHPS-A437G mutant in the natural parasite populations.

Prey naïveté rather than enemy release dominates the relation of an invasive spider toward a native predator.

Ecosystems may suffer from the impact of invasive species. Thus, understanding the mechanisms contributing to successful invasions is fundamental for limiting the effects of invasive species. Most intuitive, the enemy release hypothesis predicts that invasive species might be more successful in the exotic range than resident sympatric species owing to the absence of coevolution with native enemies. Here, we test the enemy release hypothesis for the invasion of Europe by the North American spider Mermessus trilobatus. We compare the susceptibility of invasive Mermessus trilobatus and a native species with similar life history to a shared predator with which both species commonly co‐occur in Europe. Contrary to our expectations, invasive Mermessus trilobatus were consumed three times more frequently by native predators than their native counterparts. Our study shows that invasive Mermessus trilobatus is more sensitive to a dominant native predator than local sympatric species. This suggests that the relation between the invasive spider and its native predator is dominated by prey naïveté rather than enemy release. Further studies investigating evolutionary and ecological processes behind the invasion success of Mermessus trilobatus, including testing natural parasites and rapid reproduction, are needed to explain its invasion success in Europe.

Integrative taxonomy and phylogeography of Telenomus remus (Scelionidae), with the first record of natural parasitism of Spodoptera spp. in Brazil

The egg parasitoid Telenomus remus (Hymenoptera: Scelionidae) has been investigated for classical and applied biological control of noctuid pests, especially Spodoptera (Lepidoptera: Noctuidae) species. Although T. remus was introduced into Brazil over three decades ago for classical biological control of S. frugiperda, this wasp has not been recorded as established in corn or soybean crops. We used an integrative approach to identify T. remus, combining a taxonomic key based on the male genitalia with DNA barcoding, using a cytochrome c oxidase subunit I mitochondrial gene fragment. This is the first report of natural parasitism of T. remus on S. frugiperda and S. cosmioides eggs at two locations in Brazil. We also confirmed that the T. remus lineage in Brazil derives from a strain in Venezuela (originally from Papua New Guinea and introduced into the Americas, Africa, and Asia). The occurrence of T. remus parasitizing S. frugiperda and S. cosmioides eggs in field conditions, not associated with inundative releases, suggests that the species has managed to establish itself in the field in Brazil. This opens possibilities for future biological control programs, since T. remus shows good potential for mass rearing and egg parasitism of important agricultural pests such as Spodoptera species.