A Mosquito Parasite Is Locally Adapted to Its Host but Not Temperature.

AbstractClimate change will alter interactions between parasites and their hosts. Warming may affect patterns of local adaptation, shifting the environment to favor the parasite or host and thus changing the prevalence of disease. We assessed local adaptation to hosts and temperature in the facultative ciliate parasite Lambornella clarki, which infects the western tree hole mosquito Aedes sierrensis. We conducted laboratory infection experiments with mosquito larvae and parasites collected from across a climate gradient, pairing sympatric or allopatric populations across three temperatures that were either matched or mismatched to the source environment. Lambornella clarki parasites were locally adapted to their hosts, with 2.6 times higher infection rates on sympatric populations compared with allopatric populations, but they were not locally adapted to temperature. Infection peaked at the intermediate temperature of 12.5°C, notably lower than the optimum temperature for free-living L. clarki growth, suggesting that the host's immune response can play a significant role in mediating the outcome of infection. Our results highlight the importance of host selective pressure on parasites, despite the impact of temperature on infection success.

A comparative approach for life history and functional response demonstrates similar survival strategies for Trichogramma evanescens and T. pintoi.

BACKGROUND: Egg parasitoids are important biological control agents of lepidopteran pests of agricultural crops. Trichogramma evanescens Westwood and T. pintoi Voegele (Hymenoptera: Trichogrammatidae) are egg parasitoids with worldwide importance. The parasitoid selection necessitates comparative assessment of the life table traits and functional response analysis to provide insights into their effectiveness in pest control. In this study, we examined their life table traits including survivorship and reproductivity, and functional response and associated parameters i.e., attack coefficient and handling time. RESULTS: Life table parameters, using age-stage, two-sex theory, revealed similar survival and reproductive strategies for both species. For example, the female longevity, oviposition days and fecundity did not differ between both species. Exceptionally, the male longevity of T. evanescens was shorter than that of T. pintoi. The population growth parameters such as gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (λ), and mean generation time (T) did not differ between species. The polynomial logistic regression yielded a type III functional response and a non-linear least square analysis revealed different attack coefficient and similar handling time. However, their parasitism rate differed between the lowest (five eggs) and highest (80 eggs) initial host egg densities such that T. evanescens had a lower parasitism rate at the lowest density and higher parasitism rate at the highest density. CONCLUSION: The similarity in survival strategies and minor differences in host handling of both parasitoids are discussed in terms of relevance to applied biological control applications and evolutionary traits. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Morphological and biochemical characterization of Holstein cow skin at the tail root region susceptible to Chorioptes bovis and texanus parasitism.

Cattle mange causes extreme itchiness, and the associated stress is an animal welfare concern that leads to economic losses due to decreased cattle productivity and deworming costs. This study investigated the reason why Chorioptic mites, C. bovis and C. texanus, preferentially infest the tail root region (rTR) and performed histological and biochemical analysis focusing on the volatile components of host odors that serve as the starting point for infestation of parasitic arthropods. Skin samples were taken from the rTR, lateral abdominal, and central masseteric, with the latter two designated as comparison sites. The two and three-dimensional histological analysis measured each sebaceous and sweat gland percentage per unit volume. The q-PCR analyzed the expression levels of ALDH1A1 and LOC785756, which are genes associated with volatile odoriferous compounds that serve as repellency and attractive messengers for ticks. Immunohistochemistry stained three sites with anti-androgen binding protein beta-like (ABPß-like), encoded by LOC785756, antibody. The three-dimensional analysis showed that sebaceous glands in the rTR tend to be more continuous and existed in larger masses than in other regions. The expression level of LOC785756 was significantly higher in the rTR, and immunohistochemistry revealed the presence of ABPß-like in the sebaceous gland with strong positive signals in the rTR. These results suggest that C. bovis/texanus selectively infests the rTR because that skin has well-developed sebaceous glands, including a large amount of ABPß-like, which acts as a mite attractant.

Morphological and Molecular Analysis of Two Mycophagous Nematodes, Aphelenchoides bicaudatus and A. rutgersi (Nematoda: Aphelenchoididae) from Florida Strawberry.

From 2016 to 2021, nematode surveys in Florida strawberry fields revealed several species of foliar nematodes (Aphelenchoides spp.). Aphelenchoides besseyi sensu stricto was detected only in 2016 and 2017 on photosynthetic strawberry leaves/buds, but other not well characterized populations of Aphelenchoides sp. were found on declining/dessicated leaves. Morphological analyses showed that these samples of Aphelenchoides sp. consisted of A. bicaudatus, a species detected in Florida for the first time, and A. rutgersi, a species previously reported in Florida from the citrus rhizosphere. These two species differed from A. besseyi in the shape of their tail terminus: bifurcate in A. bicaudatus; mucronate with a ventral thin mucro in A. rutgersi; and stellate in A. besseyi. One population each of these species was used for morphological and molecular analyses after being reared on Monilinia fructicola. Body and tail length differences were observed among Florida A. bicaudatus and other populations from the Far East and South Africa. Phylogenetic analyses of the rRNA gene sequences showed that Florida A. bicaudatus grouped with those of species from South Korea, Taiwan, and the Netherlands and several other populations listed as Aphelenchoides sp. from Brazil, Costa Rica, and Japan, which were considered as representatives of A. bicaudatus in this study. Similarly, sequences of Florida A. rutgersi grouped with those from environmental samples in Japan and North Carolina, which were listed as Aphelenchoides sp. and were considered as representatives of A. rutgersi in this study. Photosynthetic strawberry leaf samples were free from both A. bicaudatus and A. rutgersi, indicating that these two species did not damage strawberry. They were associated with desiccated leaves and/or propagative stolons, usually infected by fungi, confirming that they are mycetophagous under field conditions in this study. Results of soybean leaf inoculation on moist filter paper containing A. bicaudatus specimens showed that this species could become phytophagous under artificial conditions. Nematodes penetrated the leaf epidermis and migrated into the mesophyll causing leaf tissue discoloration/necrosis, which remained localized within the infested area. Soybean leaf damage was almost negligible, and no nematode reproduction was observed in the inoculated soybean areas.

Trichinella: Becoming a parasite.

Phylogenetic evidence indicates that free-living nematodes gave rise to parasitic nematodes where parasitism evolved independently at least 15 times. The high level of genetic and biological diversity among parasites dictates an equally high level of diversity in the transition to parasitism. We previously hypothesized that horizontal gene transfer (HGT) played an important role in the evolution of parasitism among early ancestors of Trichinella, mediated by an interplay of ecological and evolutionary pathways that contributed to persistence and diversification. We propose that host selection may have been associated with the metabolism of ammonia and engender a new paradigm whereby the reprogrammed nurse cell is capable of generating cyanate thereby enabling the importance of the Trichinella cyanase in the longevity of the cell. Parasites and parasitism have revealed considerable resilience against a backdrop of climate change and environmental perturbation. Here we provide a putative link between key periods in the evolution of Trichinella and major geological and climatological events dating back 500 million years. A useful lens for exploring such ideas, the Stockholm Paradigm, integrates Ecological Fitting (a foundation for host colonization and diversification), the Oscillation Hypothesis (recurring shifts between trends in generalization and specialization relative to host range), the Geographic Mosaic Theory of Coevolution (microevolutionary co-adaptive processes), and the Taxon Pulse Hypothesis (alternating events of biotic expansion i.e., exploitation in evolutionary and ecological time). Here we examine how one or more of these interactive theories, in a phylogenetic-historical context and in conjunction with HGT, may help explain the scope and depth of diversity among Trichinella genotypes.

Cannibalism facilitated by parasite infection induces dispersal in a semi-aquatic insect.

Parasites are known to have direct effects on host dispersal ability and motivation. Yet, parasites have a variety of impacts on host populations, including shaping predation and cannibalism rates, and therefore may also have indirect effects on host dispersal; these indirect pathways have not been studied. We tested the hypothesis that parasites influence host dispersal through effects on cannibalism using backswimmers (Notonecta undulata) and Hydrachnidia freshwater mites. Mite parasitism impedes swimming in backswimmers, which we found increased their vulnerability to cannibalism. We imposed a manipulation that varied cannibalism rates across experimental populations consisting of a mix of backswimmers with and without simulated parasites. Using simulated parasites allowed us to examine the effects of cannibalism without introducing infection risk. We found that the odds of dispersal for infected backswimmers increased by 2.25× with every 10% increase in the risk of being cannibalized, and the odds of dispersal for healthy backswimmers increased by 2.34× for every additional infected backswimmer they consumed. Our results suggest that cannibalism was used as an energy source for dispersal for healthy individuals, while the risk of being eaten motivated dispersal in infected individuals. These results elucidate the complex ways that parasites impact host populations and strengthen our understanding of host-parasite interactions, including host and parasite population stability and spread. This article is part of the theme issue 'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics'.

Infestation of Lithodes santolla by Eremitione tuberculata: spatial and temporal variations in parasite prevalence and effect on host growth.

The southern king crab (SKC) Lithodes santolla is a crustacean parasitised by the bopyrid Eremitione tuberculata. This study aimed to analyse spatial and temporal variations in E. tuberculata prevalence in the juvenile SKC population of San Jorge Gulf (SJG) and adjacent waters (Argentine Patagonia), and evaluate the effects of the parasite on SKC juveniles to improve our understanding of its impact as a disease on SKC health condition. Moult increment and body weight were compared between parasitised and unparasitised individuals. The prevalence of E. tuberculata in SKC juveniles varied both spatially and temporally. In the south of SJG, the prevalence was 54.5% (n = 11). Temporal prevalence analysis revealed values lower than 17.4% in mid SJG during May and September 2015. No significant differences were observed in E. tuberculata prevalence between sexes or among seasons. Eremitione tuberculata had a negative effect on SKC growth (lower body dry mass, moult increment and relative increment rate) in parasitised individuals. We hypothesised that the higher prevalence of E. tuberculata in the south SJG could be attributed to the retention of parasite larvae and the presence of the frontal system in this part of the gulf. The temporal variations could reflect host mortality. Our results suggest that bopyrid infestation may have a more important role than previously believed in the dynamics of the SKC population in mid-Patagonia.

Symbiotic endolithic microbes reduce host vulnerability to an unprecedented heatwave.

Heatwaves are increasingly severe and frequent, posing significant threats to ecosystems and human well-being. Characterised by high thermal variability, intertidal communities are particularly vulnerable to heat stress. Microbial endolithic communities that are found in marine calcifying organisms have been shown to induce shell erosion that alters shell surface colour, lowering body temperatures and increasing survival rates. Here, we investigate how the symbiotic relationship between endolithic microbes and the blue intertidal mussel Mytilus edulis mitigates thermal stress during the unprecedented 2022 atmospheric heatwave in the English Channel. Microbial infestation of the shell significantly enhanced mussel survival, particularly higher on the shore where thermal stress was greater. Using data from biomimetic temperature loggers, we predicted the expected thermal buffer and observed differences up to 3.2 °C between individuals with and without symbionts under the known conditions of the heat wave-induced mortality event. The ecological implications extend beyond individual mussels, affecting the reef-building capacity of mussels, with potential cascading effects for local biodiversity, carbon sequestration, and coastal defence. These findings emphasize the importance of understanding small-scale biotic interactions during extreme climate events and provide insights into the dynamic nature of the endolith-mussel symbiosis along a parasitic-mutualistic continuum influenced by abiotic factors.

First Report of Mermithidae (Enoplea: Mermithida) Parasitizing Adult Stable Flies in Japan.

Mermithidae is a family of nematodes that parasitize a wide range of invertebrates worldwide. Herein, we report nematodes that were unexpectedly found in three of 486 adult stable flies (Stomoxys calcitrans) captured from three farms (F1, F2, and F3) in different regions of Gifu Prefecture, Japan. We aimed to characterize these nematodes both at the morphological and molecular level. Morphological studies revealed that the nematodes were juveniles of Mermithidae. Phylogenetic analysis based on 18S and 28S rDNA indicated that the mermithids from farms F1 and F2 could be categorized into the same cluster as Ovomermis sinensis and Hexamermis sp., whereas the mermithid from farm F3 clustered with Amphimermis sp. Additionally, these mermithids could be categorized within the same clusters as related mermithids detected in Japan that parasitize various arthropod orders. Our findings suggest that these stable flies may have been parasitized by mermithids already present in the region and that genetically distinct species of mermithids occur across Japan. To the best of our knowledge, this is the first report of mermithids parasitizing adult stable flies in Japan.

With the dead under the mat: the zombie ant extended phenotype under a new perspective.

Some parasitic fungi can increase fitness by modifying the behavior of their hosts. These behaviors are known as extended phenotypes because they favor parasitic gene propagation. Here, we studied three lineages of Ophiocordyceps, a fungus that infects ants, altering their conduct before death. According to fungal strategy, ants may die in leaf litter, with entwined legs in branches, under the moss mat, or biting plant tissue. It is critical for parasites that the corpses stay at these places because Ophiocordyceps exhibit iteroparity, possibly releasing spores in multiple life cycles. Thus, we assumed substrate cadaver permanence as a fungi reproductive proxy and corpse height as a proxy of cadaver removal. We hypothesize that biting vegetation and dying in higher places may increase the permanence of ant corpses while avoiding possible corpse predation on the forest floor. We monitored over a year more than 4000 zombie ants in approximately 15 km2 of undisturbed tropical forest in central Amazonia. Our results show a longer permanence of corpses with increasing ground height, suggesting that the parasites may have better chances of releasing spores and infecting new hosts at these places. We found that the zombie ants that last longer on the substrate die under the moss mat in tree trunks, not necessarily biting vegetation. The biting behavior appears to be the most derived and complex mechanism among Ophiocordyceps syndromes. Our results put these findings under a new perspective, proposing that seemingly less complex behavioral changes are ecologically equivalent and adaptative for other parasite lineages.

Reactions of wintering passerines to male calls of the European cuckoo Cuculus canorus.

The reaction of birds to the nest parasite, the European cuckoo Cuculus canorus, has been the subject of extensive testing in various aspects. However, while the cuckoo is a long-distance migrant, some of its hosts are sedentary species. In this study, we aimed to investigate whether species, primarily hosts, react to the presence of the cuckoo also in the winter season. This behaviour may involve an attempt to drive the parasite away from locations that will subsequently become their breeding sites. During playback experiments conducted in the winter of 2021/2022 in Poland, we demonstrated that numerous bird species react to the male cuckoo calls in winter. These calls may be perceived as a source of danger, particularly by cuckoo hosts, who responded to this call more frequently than non-hosts and the control species (pigeon). Nonetheless, the birds' reactions were not strong, as they did not approach the source of the call. However, our results are constrained by the limited number of cuckoo host species wintering in Poland. To better evaluate the intensity of bird responses to the male cuckoo's call during the non-breeding season, further studies should be conducted in regions where a greater variety of species, especially those most susceptible to parasitism, overwinter.

Modelling suggests Wolbachia-induced cytoplasmic incompatibility in oak gall wasps with cyclical parthenogenesis.

Oak gall wasps typically exhibit a life cycle with one sexual and one asexual generation each year. These wasps can carry various endosymbionts, one of which is the maternally inherited bacterium Wolbachia that can induce several reproductive manipulations on its host. Cytoplasmic incompatibility (CI) has been described as the most prominent of these manipulations. CI leads to embryonic mortality in the hosts' offspring when infected males mate with either uninfected females or with females that harbour different Wolbachia strains. It has been hypothesized that Wolbachia can induce CI in oak gall wasps. To address this hypothesis, we derived a mathematical model to investigate the spread of a bacterial infection in naive populations and to determine the plausibility of CI occurrence. To validate our model, we used published data from Wolbachia-infected Belonocnema treatae populations in two approaches. Our first approach uses measurements of infection frequencies and maternal transmission in the sexual generation. For the second approach, we extended the model to compare predictions to estimates of mtDNA-haplotypes, which, like Wolbachia, are maternally inherited, and can therefore be associated with the infection. Both approaches indicate that CI is present in these populations. Our model can be generalized to investigate the occurrence of CI not only for oak gall wasps but also for other species.

Gastrointestinal Helminths in Wild Felids in the Cerrado and Pantanal: Zoonotic Bioindicators in Important Brazilian Biomes.

Environmental changes in the Brazilian Pantanal and Cerrado facilitate the spread of parasitic diseases in wildlife, with significant implications for public health owing to their zoonotic potential. This study aimed to examine the occurrence and diversity of gastrointestinal parasites in wild felids within these regions to assess their ecological and health impacts. We collected and analyzed helminth-positive samples from 27 wild felids using specific taxonomic keys. Diverse parasitic taxa were detected, including zoonotic helminths, such as Ancylostoma braziliense, Ancylostoma caninum, Ancylostoma pluridentatum, Toxocara cati, Toxocara canis, Dipylidium caninum, Taenia spp., Echinococcus spp., and Spirometra spp. Other nematodes, such as Physaloptera praeputialis and Physaloptera anomala, were identified, along with acanthocephalans from the genus Oncicola and a trematode, Neodiplostomum spp. (potentially the first record of this parasite in wild felids in the Americas). Human encroachment into natural habitats has profound effects on wild populations, influencing parasitic infection rates and patterns. This study underscores the importance of continuous monitoring and research on parasitic infections as a means of safeguarding both wildlife and human populations and highlights the role of wild felids as bioindicators of environmental health.

Hepatic immune response of Coilia nasus infected with Anisakidae during ovarian development.

Anisakidae parasitism is a prevalent disease in wild populations of Coilia nasus, and can result in a significant loss of germplasm resources. To elucidate the immune response mechanism of C. nasus livers to Anisakidae infection, we collected and analysed 18 parasitic and 18 non-parasitic livers at gonadal developmental stages II, III, and V using histopathology, molecular biology and transcriptome methods. The hepatic portal area of the parasitic group exhibited an increase in the fibrous stroma and thickened hepatic arteries with positive Ly-6G staining, indicating inflammation and immune responses in the liver. Hepatocyte cytokine levels and the expression of liver function-related genes indicated that fish livers responded similarly to Anisakidae parasitism across different gonadal developmental stages. Oxidative stress indices showed more intense changes in stage II samples, whereas gene expression levels of Nrf2 and C3 were significantly increased in parasitised livers during stage III and V. Liver transcriptome sequencing identified 2575 differentially expressed genes between the parasitic and non-parasitic groups at the three gonadal developmental stages. KEGG pathway analysis showed that natural killer cell-mediated cytotoxicity, the NOD-like receptor signaling pathway, neutrophil extracellular trap formation, and other immune pathways were significantly enriched. Expression patterns varied across developmental stages, suggesting that innate immunity was primarily responsible for the liver immune response to Anisakidae infection during C. nasus migration, possibly related to water temperature changes or shifts in the gonadal developmental stage. In summary, this study investigated the immune response of C. nasus to Anisakidae parasitism under natural conditions, focusing on reproductive aspects and environmental changes, thereby establishing a foundation for elucidating the molecular mechanisms underlying the immune response of Anisakidae in C. nasus.

Genomic insights into the evolution of secondary metabolism of Escovopsis and its allies, specialized fungal symbionts of fungus-farming ants.

The metabolic intimacy of symbiosis often demands the work of specialists. Natural products and defensive secondary metabolites can drive specificity by ensuring infection and propagation across host generations. But in contrast to bacteria, little is known about the diversity and distribution of natural product biosynthetic pathways among fungi and how they evolve to facilitate symbiosis and adaptation to their host environment. In this study, we define the secondary metabolism of Escovopsis and closely related genera, symbionts in the gardens of fungus-farming ants. We ask how the gain and loss of various biosynthetic pathways correspond to divergent lifestyles. Long-read sequencing allowed us to define the chromosomal features of representative Escovopsis strains, revealing highly reduced genomes composed of seven to eight chromosomes. The genomes are highly syntenic with macrosynteny decreasing with increasing phylogenetic distance, while maintaining a high degree of mesosynteny. An ancestral state reconstruction analysis of biosynthetic pathways revealed that, while many secondary metabolites are shared with non-ant-associated Sordariomycetes, 56 pathways are unique to the symbiotic genera. Reflecting adaptation to diverging ant agricultural systems, we observe that the stepwise acquisition of these pathways mirrors the ecological radiations of attine ants and the dynamic recruitment and replacement of their fungal cultivars. As different clades encode characteristic combinations of biosynthetic gene clusters, these delineating profiles provide important insights into the possible mechanisms underlying specificity between these symbionts and their fungal hosts. Collectively, our findings shed light on the evolutionary dynamic nature of secondary metabolism in Escovopsis and its allies, reflecting adaptation of the symbionts to an ancient agricultural system.IMPORTANCEMicrobial symbionts interact with their hosts and competitors through a remarkable array of secondary metabolites and natural products. Here, we highlight the highly streamlined genomic features of attine-associated fungal symbionts. The genomes of Escovopsis species, as well as species from other symbiont genera, many of which are common with the gardens of fungus-growing ants, are defined by seven chromosomes. Despite a high degree of metabolic conservation, we observe some variation in the symbionts' potential to produce secondary metabolites. As the phylogenetic distribution of the encoding biosynthetic gene clusters coincides with attine transitions in agricultural systems, we highlight the likely role of these metabolites in mediating adaptation by a group of highly specialized symbionts.

Subcutaneous occurrence of encysted Acanthocephala in an anuran amphibian from Brazil.

Acanthocephalans, in their adult stage, are obligatory parasites of many types of vertebrates, including anuran amphibians. Their complex life cycle always involves an arthropod intermediate host but may include non-obligatory strategies that could improve transmission success, such as paratenic infections. In paratenic hosts, these parasites are normally found loose in the body cavity or encysted in internal organs. Here, we present the first report of acanthocephalans found encysted under the skin of an amphibian (i.e., external to its body cavity). The specimen, a clay robber frog [Haddadus binotatus (Spix, 1824)], had been collected in an Atlantic Forest area in southeastern Brazil. Upon examination of the frog, we recovered two specimens of acanthocephalan (Order Echinorhynchida) encysted under the skin of its venter. Considering the host's relatively small size and its thin ventral musculature, we believe that the acanthocephalans may have accidentally trespassed the muscular tissue while attempting to encyst in the frog's internal body wall.

Trophic interactions in microbiomes influence plant host population size and ecosystem function.

Plant microbiomes that comprise diverse microorganisms, including prokaryotes, eukaryotes and viruses, are the key determinants of plant population dynamics and ecosystem function. Despite their importance, little is known about how species interactions (especially trophic interactions) between microbes from different domains modify the importance of microbiomes for plant hosts and ecosystems. Using the common duckweed Lemna minor, we experimentally examined the effects of predation (by bacterivorous protists) and parasitism (by bacteriophages) within microbiomes on plant population size and ecosystem phosphorus removal. Our results revealed that the addition of predators increased plant population size and phosphorus removal, whereas the addition of parasites showed the opposite pattern. The structural equation modelling further pointed out that predation and parasitism affected plant population size and ecosystem function via distinct mechanisms that were both mediated by microbiomes. Our results highlight the importance of understanding microbial trophic interactions for predicting the outcomes and ecosystem impacts of plant-microbiome symbiosis.

Trypanosoma vivax in and outside cattle blood: Parasitological, molecular, and serological detection, reservoir tissues, histopathological lesions, and vertical transmission evaluation.

This study reports assessment of the sensitivity of diagnostic techniques to detect T. vivax in experimentally infected cattle. Additionally, it describes T. vivax extravascular parasitism during the acute and chronic phases of trypanosomosis and congenital transmission. The T. vivax diagnosis was compared using blood samples collected from the jugular, coccygeal and ear tip veins. For this study, 13 males and two females were infected with ≈ 1 × 106 viable T. vivax trypomastigotes (D0). One animal was kept as a negative control during the entire study. The 13 infected males were euthanized between 14 and 749 days post-infection (DPI). After confirming the cyclicity of both females (9 months of age), they were naturally mated with a bull. One female was euthanized at 840 DPI, and the other at 924 DPI. The two calves, one from each female, were euthanized at six months of age (924 DPI), and the negative control at 924 DPI. During this period, T. vivax in blood was assessed using direct methods (Woo test, cPCR, microscopic examination of fresh wet blood films and parasite quantification - Brener method), and serological methods (IFAT, ELISA, and IA). Tissue samples were collected from the liver, spleen, brain, cerebellum, heart, testicles, epididymis, kidneys, eyeballs, pre-scapular lymph nodes, ear tips, mammary glands, uterus, and ovaries. The protozoan DNA was examined using LAMP. There was no difference in the detection of T. vivax using the Woo test and Brener method among the jugular, coccygeal, and ear tip veins. The sensitivity of the detection methods varied depending on the disease phase. Direct methods (Woo test, Brener method, and cPCR) demonstrated higher sensitivity during the acute phase, while serological methods (IFAT, ELISA, and IA) were more sensitive during the chronic phase. Anti-T. vivax antibodies were detected up to 924 DPI. Tissue evaluation using LAMP demonstrated the presence of T. vivax DNA and associated histopathological changes up to 840 or 924 DPI. Only in mammary glands and ovaries was no DNA detected. The most frequently observed histopathological alteration was lymphohistioplasmocytic inflammatory infiltrate. No transplacental transmission of T. vivax was observed.

Behavioural response to gastrointestinal parasites of yearling dairy calves at pasture.

AIMS: To investigate the association between gastrointestinal parasites (GIP) and animal behaviour in dairy calves under New Zealand pastoral conditions, using animal-mounted, accelerometer-based sensors. METHODS: Thirty-six, 5-6-month-old, Friesian-Jersey, heifer calves fitted with animal activity sensors to track behaviour were randomly allocated to one of two treatment groups. Half the animals were challenged with an oral dose of 20,000 larvae of Ostertagia ostertagi and Cooperia oncophera once a week for 3 weeks and half were unchallenged. Five weeks after the last dose, seven infected and nine uninfected animals were treated with an oral anthelmintic (AHC) and data collected for a further week. Accelerometer data were classified into minutes per day eating, ruminating, in moderate-high activity or in low activity. Live weight and faecal egg counts (FEC) were recorded weekly over the study period. All animals co-grazed a newly sown pasture not previously grazed by ruminants and were moved every week to fresh grazing. Treatment status was blinded to those managing the animals which were otherwise treated identically. RESULTS: Complete behavioural records were available from 30/36 calves, (13 challenged and 17 unchallenged). Before treatment with AHC, FEC increased in infected and un-treated calves over the study, while uninfected animals maintained a near zero FEC. There was no difference in live weight gain between the two groups over the study period. Bayesian, multinomial regression predicted differences in animal behaviour between infected and uninfected animals that were not treated with AHC over the 7 weeks following initial infection. Parasitised calves not treated with AHC were less active and spent up to 6 (95% highest density interval (HDI) = 1-11) minutes/day less in low level activity and up to 15 (95% HDI = 7-20) minutes/day less in moderate to high level activity. They ruminated up to 9 (95% HDI = 2-15) minutes/day more and ate up to 10 (95% HDI = 2-19) minutes/day more than control calves that were not treated with AHC. The effect of AHC on time spent in each behaviour differed between infected and uninfected calves and increased the coefficient of dispersion of the behavioural data. CONCLUSIONS AND CLINICAL RELEVANCE: Small differences in animal behaviour can be measured in calves with GIP. However, to use this to target treatment, further validation studies are required to confirm the accuracy of behavioural classification and understand the complex drivers of animal behaviour in a dynamic and variable pasture-parasite-host environment.

Genomic basis of adaptation to climate and parasite prevalence and the importance of odorant perception in the ant Temnothorax longispinosus.

A co-evolutionary arms race ensues when parasites exhibit exploitative behaviour, which prompts adaptations in their hosts, in turn triggering counter-adaptations by the parasites. To unravel the genomic basis of this coevolution from the host's perspective, we collected ants of the host species Temnothorax longispinosus, parasitized by the social parasite Temnothorax americanus, from 10 populations in the northeastern United States exhibiting varying levels of parasite prevalence and living under different climatic conditions. We conducted a genome-wide association study (GWAS) to identify single nucleotide polymorphisms (SNPs) associated with both prevalence and climate. Our investigation highlighted a multitude of candidate SNPs associated with parasite prevalence, particularly in genes responsible for sensory perception of smell including odorant receptor genes. We further focused on population-specific compositions of cuticular hydrocarbons, a complex trait important for signalling, communication and protection against desiccation. The relative abundances of n-alkanes were correlated with climate, while there was only a trend between parasite prevalence and the relative abundances of known recognition cues. Furthermore, we identified candidate genes likely involved in the synthesis and recognition of specific hydrocarbons. In addition, we analysed the population-level gene expression in the antennae, the primary organ for odorant reception, and established a strong correlation with parasite prevalence. Our comprehensive study highlights the intricate genomic patterns forged by the interplay of diverse selection factors and how these are manifested in the expression of various phenotypes.