Parasite Larvae Research Articles

Molecular quantification of parasitic sea louse larvae depends on species and life stage.

Sea lice cause substantial economic and environmental harm to Norway's aquaculture industry and wild salmonid populations. Rapid, accurate quantification of lice larval densities in coastal waters remains the greatest bottleneck for providing empirical data on infestation risk within wild salmon habitats and aquaculture production regions. We evaluated the capability of droplet digital PCR (ddPCR) as an absolute quantification method for the planktonic stages of two parasitic louse species, Lepeophtheirus salmonis (Krøyer) and Caligus elongatus (von Nordman). Results demonstrated linear relationships between the DNA quantity measured and the number of spiked larvae for both species and life stages. However, L. salmonis contained a significantly greater number of DNA copies than C. elongatus individuals and for C. elongatus, nauplii displayed a significantly higher number of DNA copies than copepodids. Our results suggest that ddPCR can effectively enumerate louse larvae, but interpreting ddPCR results differ between the two louse species. Obtaining larval abundance estimates from marine plankton samples will depend on the nauplii to copepodid ratio for C. elongatus, but not for L. salmonis.

Landscape complexity effects on Brassicogethes aeneus abundance and larval parasitism rate: a two-year field study

Global biodiversity has suffered a decline primarily attributed to landscape simplification and intensified agricultural practices. Agricultural environments, characterized by homogeneity and frequent disturbances, are often suboptimal habitats for various insect species. While agricultural fields do favour pests, they generally fail to provide suitable habitats for natural enemies. The inclusion of diverse supporting habitats, such as semi-natural habitats, grassy and woody field margins etc. surrounding agricultural fields, play a crucial role in fostering effective biodiversity conservation. Moreover, determining the influence of different adjacent habitat types is essential in elucidating their influence on pest abundance and parasitism rates. Our two-year field study focused on assessing the abundance of Brassicogethes aeneus and its parasitism rate. The findings revealed that the adjacent habitat type did not significantly increase pest abundance and the parasitism rate of B. aeneus larvae consistently stayed over the threshold for effective biological control throughout the fields. This was attributed to the high proportion (35 and 38% in the 2 study years) of semi-natural habitats within most of the 1 km radius study areas. While our study did not identify any specific adjacent habitat type or habitat within a 1 km radius that directly impacted B. aeneus abundance, it emphasises the intricate interplay between the pests, parasitism and the surrounding environment because the interactive effect of distance from the crop edge and habitat type had a significant influence on B. aeneus infestation levels but not on parasitism. Decision tree analysis suggests that > 18% semi-natural habitat is needed to ensure sufficient levels of parasitism for effective biological control. A comprehensive understanding of habitats that influence not only B. aeneus but also other pests is critical for the successful implementation of IPM strategies and conservation initiatives within the agricultural sector.

Individually or as a Team-The Immunological Milieu in the Lung Caused by Migrating Single-Sex or Mixed-Sex Larvae of Schistosoma mansoni.

While the lung is considered an efficient site for stopping the larvae of the acute Schistosoma spp. infection phase from migrating through extensive inflammatory responses in the surrounding tissues, little is known about these processes. To date, the highest resistance to infection has been achieved in experimental studies with radiation-attenuated cercariae immunization, which elicits a strong Th1/Th2 response in the lung and results in up to 80% protection. Based on our own studies demonstrating a systemic, unpolarized Th1/Th2 response resulting from infection with male or female Schistosoma mansoni, we hypothesize that this atypical immune response is already detectable during the pulmonary passage of parasite larvae. Therefore, we examined the immune milieu in the lungs of mice caused by migrating schistosome larvae, either male or female (single-sex groups) or male + female (bisexual control), 4 and 16 days after infection in bronchoalveolar lavage and lung tissue by flow cytometry, qPCR, and multiplex analyzes. Our results show only minor differences in the inflammatory profile between the single-sex groups but significant differences compared with the bisexual control group. Both single-sex infected groups have increased expression of inflammatory markers in lung tissue, higher numbers of cytotoxic T cells (day 4 post-infection) and more T helper cells (day 16 post-infection), compared with the bisexual control group. A single-sex infection, regardless of whether it is an infection with male or female cercariae, causes an immune milieu in the lung that is clearly different from an infection with both sexes. In terms of identifying therapeutic targets to achieve resistance to re-infection, it is of great scientific interest to identify the differences in the inflammatory potential of male or female and male + female parasites.

Factors shaping the abundance of two butterflies sharing resources and enemies across a biogeographic region

AbstractAimIntraspecific variation in species relative abundance is shaped by a complex interplay of abiotic and biotic factors, making it both necessary and challenging to assess their combined relative importance in explaining variations across space and time. We used two congeneric butterfly species for which extensive count data and a deep understanding of their natural history is available to test three hypotheses explaining intraspecific variation in their abundance: (H1) seasonal dispersal behaviour driven by climate, (H2) resource availability and (H3) apparent competition mediated via shared parasitoids.TaxonGonepteryx rhamni (Brimstone) and G. cleopatra (Cleopatra).LocationNE Iberian Peninsula, where both species coexist, and a nearby archipelago (Balearic Islands), where only Cleopatra occurs.MethodsWe analysed spatial abundance variations for both species in the mainland and island–mainland differences in the abundance of Cleopatra. Abiotic and biotic factors, including temperature, host plant and overwintering habitat availability, larval parasitism and density dependence, were tested to explain the observed variations.ResultsH1 can explain variation in butterfly abundance between mainland regions since in warmer summers populations increased in cooler areas but decreased in warmer areas. H2 explains the variation within mainland climate regions with a strong positive relationship between resource availability and abundance but is unlikely to explain the island–mainland variation in the abundance of Cleopatra. H3 could neither explain biogeographical variation in abundance because although richer parasitoid communities were found on the mainland, larval mortality rates were similar or lower on the mainland than in the islands.Main ConclusionsClimate and resource availability jointly account for variation in butterfly abundance across the mainland, but neither these factors nor parasitism can explain island–mainland differences. Both coexisting butterfly species and their larval parasitoids may have undergone evolutionary processes, resulting in spatial segregation that promotes the coexistence of the two butterfly species on the mainland.

Conserved temperature requirements but contrasting responses to humidity across oviposition preferences in temperate grasshoppers

The right choice of an oviposition site is a crucial task for oviparous species without maternal care. In contrast to well investigated biotic factors, e.g., larval food preferences, parasitism, predation, and competition avoiding, abiotic factors affecting oviposition preferences in insects have been rarely investigated in comparative studies. To improve our current understanding of oviposition site selection in Orthoptera, we investigated the influence of substrate temperature and moisture on the oviposition behaviour of 14 temperate grasshopper species. Conspecific groups of adults were kept in arenas with simultaneous temperature and moisture gradients. For each ootheca produced during the experiment (n = 1192) we recorded its depth and local microclimatic conditions. Our results indicate that microclimatic oviposition preferences significantly differ among species, however, correlations between adult habitat preferences and microclimatic oviposition preferences were surprisingly weak. Even oligothermic species preferred substrate temperatures around 30 °C and some xerothermic species preferred higher humidity. The hypothesized tendency to place oothecae closer to the ground within grass tussocks under hot and dry conditions was confirmed. It is possible that species evaluate microclimatic conditions for oviposition in the context of occupied habitat, i.e., in a relative rather than absolute manner.

The strategy of optimal control for managing sugarcane shoot borer larvae

Pests and plant diseases pose significant challenges to Indonesia's agricultural development of sugar cane. The fall in national sugar productivity can be attributed, in part, to the presence of sugar cane shoot borer bugs. Managing sugar cane shoot borer pests is a crucial aspect of agriculture. The objective of this scientific study is to ascertain the optimal approach for the introduction of parasitoid larvae of sugarcane shoot borer pests. This will be done by looking at the Lotka-Volterra equation's stability and finding the best way to control it. This is a mathematical model used to show how biological control systems work. Specifically, the study focuses on the biological control of sugarcane shoot borer pests using their parasitic larvae, the Diatraeophaga striatalis Towns. The researchers opted for the qualitative descriptive approach, employing analytical tools derived from Miles and Huberman's four-stage framework. The equilibrium point and optimal control analyses show that the model presents various outcomes with distinct methods. These findings will be further examined in the subsequent sections of this paper.

Acalypha ostryifolia: a natural refuge for Chloridea virescens and Helicoverpa zea (Lepidoptera: Noctuidae) in the Southern United States

Abstract The tobacco budworm, Chloridea virescens (F.), and corn earworm, Helicoverpa zea (Boddie) (heliothines), have had a long-intertwined relationship with respect to their importance as pests in agricultural production systems. Previous studies have examined the impacts of early-season wild host plants on local population density and distribution of these 2 insects on cultivated crops such as cotton, Gossypium hirsutum L., and soybean, Glycine max L. Additional studies have examined the importance of wild host plants, which act as a refuge of nonexposed populations of C. virescens and H. zea to insecticidal toxins from the soil bacterium, Bacillus thuringiensis (Bt) Berliner. The current study examined hophornbeam copperleaf, Acalypha ostryifolia Riddell, as a host plant for mid-late season populations of C. virescens and H. zea. Patches of A. ostryifolia were sampled along roadsides and the edges of fields from 2014 to 2020 in Mississippi, USA, to examine larval density, species composition, and parasitism of heliothines on this wild host plant. Insects were collected from the end of June through October. The largest densities (based on the number of caterpillars per sweep) of heliothines were over one larva per sweep. Overall, 49.5% of the collected caterpillars were determined to be tobacco budworms, while 50.5% were corn earworms. Parasitism rates ranged from approximately 1–30%, increasing throughout the season. In general, densities of heliothines encountered on A. ostryifolia were greater than densities reported for other wild host plants. Hophornbeam copperleaf is an important natural refuge for both heliothines from Bt toxins and synthetic insecticide applications.

Gelatin medium for preserving of Trichinella spp. for quality control in laboratories - estimation of larvae viability.

Official food control laboratories ensure food safety using reliable, validated methods. Council Regulations (EC) No. 853/2004, 854/2004 and 882/2004 of the European Parliament established hygiene rules the production of food of animal origin, together with requirements for official controls. This leads to detailed requirements for Trichinella control set out in Commission Implementing Regulation (EU) 2015/1375 of 10 August 2015. These regulations require the laboratory to participate in proficiency testing (PT) to confirm their competence and improve the quality of testing, and require the PT Organizer to use methods for the preparation and preservation of parasite larvae in order to evaluate and improve detection. Traditional methods of preparing such larvae expose them to rapid degradation, making it necessary to simultaneously isolate the larvae and place them in meatballs to ensure quality. We developed a technique for preserving of Trichinella spp. for quality control such as PT sample preparation. The procedure protects larvae against toxic oxygen activity and bacterial destruction via a gelatin barrier. To estimate the viability of larvae preserved by this method, gelatin capsules with 10 larvae of T. spiralis in each were stored (4-8 °C) during 45 days of an experiment. Samples were tested at 2 day intervals (3 samples each day of testing). In total, 75 samples were tested. Larvae remained alive up to 3 weeks. The number of living larvae diminished after 27 days through day 43, after which no living larvae were observed. The gelatin medium procedure facilitated easy, high-throughput sample preparation and supported 100% recovery for 3 weeks. The method allows fast, efficient and accurate PT sample preparation.

Microbial communities are indicators of parasite infection status.

Growing evidence suggests that microbiomes have been shaping the evolutionary pathways of macroorganisms for millennia and that these tiny symbionts can influence, and possibly even control, species interactions like host-parasite relationships. Yet, while studies have investigated host-parasites and microbiomes separately, little has been done to understand all three groups synergistically. Here, we collected infected and uninfected Eurypanopeus depressus crab hosts from a coastal North Carolina oyster reef three times over 4 months. Infected crabs demonstrated an external stage of the rhizocephalan parasite, Loxothylacus panopaei. Community analyses revealed that microbial richness and diversity were significantly different among tissue types (uninfected crab, infected crab, parasite externae and parasite larvae) and over time (summer and fall). Specifically, the microbial communities from parasite externae and larvae had similar microbiomes that were consistent through time. Infected crabs demonstrated microbial communities spanning those of their host and parasite, while uninfected crabs showed more distinctive communities with greater variability over time. Microbial communities were also found to be indicators of early-stage infections. Resolving the microbial community composition of a host and its parasite is an important step in understanding the microbiome's role in the host-parasite relationship and determining how this tripartite relationship impacts coevolutionary processes.

Abundance, diversity and richness of natural enemies of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), in Zambia.

The fall armyworm (FAW), Spodoptera frugiperda, an invasive pest originating from the Americas is a serious pest threatening cereal production and food security in Zambia. We studied the prevalence and abundance of natural enemies of FAW in three Agroecological regions (AERs I, II, and III) to identify those that could potentially serve as bio-control agents. Sampling of FAW parasitoids and predators was done along trunk roads at intervals of 10 km. Molecular sequence analysis and morphological characterization were used to identify natural enemies. Over 11 species of FAW natural enemies, including egg, egg-larval, and larval parasitoids, and predators, were identified in Zambia. The mean number of natural enemies and species richness was higher in AER I and IIa. Consequently, egg parasitism was highest in those two regions, at 24.5% and 12.2%, respectively. Larvae parasitism was highest in AER I (4.8%) and AER III (1.9), although no significant differences were observed. The most abundant and widely distributed parasitoid was Drino sp. (Diptera: Tachinidae), while Rhynocoris segmentarius (Germar) (Hemiptera: Reduviidae) and Belanogaster sp. (Hymenoptera: Vespidae) were the most prevalent predators. Our study reveals the presence of two natural enemies belonging to the genus Tiphia and Micromeriella, uncommon to FAW. Significant differences in the number of parasitoids were observed in polycropping, with the highest recovery of 12 ± 10% from maize + cowpeas + pumpkin and watermelon mixed cropping. The higher the rainfall, the lower the number of natural enemies recorded. Variations in rainfall patterns which affect FAW availability, cropping systems and the three AERs may explain natural enemies' species diversity in Zambia. The information provided in this study can aid the development of a national biological control programme for sustainable management of fall armyworm.

Direct and indirect effects of fire on parasites in an African savanna

Abstract Fires in grassy ecosystems consume vegetation and initiate high‐quality regrowth, which results in pyric herbivory when mammalian grazers concentrate feeding in recent burns. For environmentally transmitted parasites with transmission mechanisms linked to vegetation structure, fire should exert direct effects on parasites, as well as indirect effects resulting from subsequent enhanced herbivory, which can affect parasite input and exposure to environmental conditions. We combined an experimental manipulation with observational data in the Serengeti National Park to investigate the direct and indirect effects of fire on parasites. We assessed the direct effects of fire by measuring changes in parasitic nematode larvae in the grass layer before and after fire on paired experimental burned and control plots. To investigate indirect effects linked to pyric herbivory, we sampled herbivore dung, grass biomass, ground temperature and larval densities every month for 5 months following fire in seven pairs of burned and unburned monitoring plots. Finally, to assess if fire‐driven changes to larval densities affected host infection burdens, we collected faecal samples from a key host, Grant's gazelle (Nanger granti), each month for 5 months to estimate within‐host parasite burdens. Fire killed all larvae and increased grazer dung inputs by 40% for 2 months following fire. Dung inputs after fire led to larval parasite recolonization of burned patches, but intense herbivory kept grass short and larval densities were associated with changes in ground temperature linked to grass biomass and ambient temperature. Grant's gazelles had lower parasite burdens when sampled in areas with higher compared to lower burned area fraction. Fire and pyric herbivory change the densities of larval parasites in the environment and divide the landscape into burned and unburned regions with distinct infection risks for local herbivores. The indirect effects quantified here represent a novel finding with major implications for all grazing systems impacted by fire.

Polymorphic parasitic larvae cooperate to build swimming colonies luring hosts

Parasites have evolved a variety of astonishing strategies to survive within their hosts, yet the most challenging event in their personal chronicles is the passage from one host to another. It becomes even more complex when a parasite needs to pass through the external environment. Therefore, the free-living stages of parasites present a wide range of adaptations for transmission. Parasitic flatworms from the group Digenea (flukes) have free-living larvae, cercariae, which are remarkably diverse in structure and behavior.1,2 One of the cercariae transmission strategies is to attain a prey-like appearance for the host.3 This can be done through the formation of a swimming aggregate of several cercariae adjoined together by their tails.4 Through the use of live observations and light, electron, and confocal microscopy, we described such a supposedly prey-mimetic colony comprising cercariae of two distinct morphotypes. They are functionally specialized: larger morphotype (sailors) enable motility, and smaller morphotype (passengers) presumably facilitate infection. The analysis of local read alignments between the two samples reveals that both cercaria types have identical 18S, 28S, and 5.8S rRNA genes. Further phylogenetic analysis of these ribosomal sequences indicates that our specimen belongs to the digenean family Acanthocolpidae, likely genus Pleorchis. This discovery provides a unique example and a novel insight into how morphologically and functionally heterogeneous individuals of the same species cooperate to build colonial organisms for the purpose of infection. This strategy bears resemblance to the cooperating castes of the same species found among insects.5.

Prevalence of Intestinal Parasites among Children Accessing Medical Healthcare at the Federal Medical Centre Keffi, Nasarawa State, Nigeria

Aim: This work was conducted between the period of April 2022 and March 2023 to investigate the prevalence and predisposing factors of enteric parasites among children accessing medical healthcare at the Federal Medical Center keffi, Nasarawa State.
 Study Design: The study was a cross-sectional study. 
 Methodology: Fresh stool specimens were collected into sterile bottles from children aged 1-15 (246 males and 194 females) who accessed medical healthcare at the Federal Medical Center keffi, Nasarawa State between the period of April 2022 and March 2023. Information such as age, gender, and drinking water sources were obtained from the subjects through a structured questionnaire. The stool specimens were observed visually for colour, consistency, and presence of blood, pus, and adult worms while the concentration of the eggs, cysts, and larvae of the intestinal parasites was carried out using the formol ether method and viewed with X10 and X40 magnifications of the binocular microscope. Data obtained from this study were analyzed using the chi-square test by the use of Statistical Package for Social Sciences (SPSS) version (21.0). Values obtained were considered significant at 95% probability.
 Results: An overall prevalence of 27.26% was obtained in the study participants with a total of five species of intestinal parasites identified. The parasites include; Entamoeba coli, Entamoeba histolytica, Giardia lamblia, Strongyloides stercoralis, and Trichomonas hominis. Entamoeba. histolytica was the most prevalent (15.45%) while S. stercoralis was the least prevalent (1.36%). In this study, males recorded a higher prevalence of Entamoeba. histolytica (16.49%) than females (14.63%) likewise for E. coli (5.14%) and (4.07%), Strongyloides stercoralis (1.55%) and (1.22%) respectively. In contrast, females recorded a higher prevalence of Giardia lamblia (2.85%) than males (2.58%) and Trichomonas hominis (3.25%) and (1.03%) respectively. The prevalence of intestinal parasites varied significantly among the age groups, with the age group 1-5 years being the most susceptible to E. histolytica (45.71%). Children who drank river water had the highest prevalence of parasitic infection (57.14%) while those who drank borehole water had the lowest majority (14.29%).
 Conclusion: The high prevalence of intestinal parasites observed in this study in relation to the sources of drinking water of the subjects suggests a major predisposing factor to intestinal parasitic infections. Therefore, the provision of potable drinking water and public enlightenment on proper hygiene practices in the study area is of great importance.

Diversity of trematode cercariae among naturally infected lymnaeid snails from Phayao, Thailand.

Lymnaeids are aquatic snails playing an important role in the transmission of many parasitic trematode species of veterinary and medical importance. In this study, we assessed the presence of cercarial flukes in naturally infected lymnaeid snails from Phayao province, Thailand, and determined the species diversity of both the intermediate snail hosts and parasite larvae. A total of 3,185 lymnaeid snails were collected from paddy fields at 31 sites in eight districts of Phayao province between October 2021 and December 2022. Larval fluke infection was assessed using the cercarial shedding method. The collected snails as well as emerging cercariae were identified at the species level via morphological and molecular methods. The sequences of snail internal transcribed spacer region 2 (ITS2) and cercarial 28S ribosomal RNA gene (28S rDNA) and cytochrome C oxidase1 (Cox1) were determined by PCR amplification and sequencing. Three species of lymnaeid snails were detected in this study, including Radix (Lymnaea) rubiginosa (Michelin, 1831), Radix (Lymnaea) swinhoei (Adams, 1866) and Austropeplea viridis (Quoy & Gaimard, 1832), of which R. rubiginosa was the most abundant, followed by A. viridis and R. swinhoei. The overall rate of trematode cercarial infection in the lymnaeid snails was 2.8% (90/3,185); the cercarial infection rate in R. rubiginosa and A. viridis was 3.5% (60/1,735) and 3.1% (30/981), respectively. No larval fluke infection was observed in the studied R. swinhoei (0/469). Nine morphotypes of cercariae were detected at 15 sites from four districts. The emerging cercariae were molecularly identified as Clinostomum sp., Aporocotylidae sp., Apharyngostrigea sp., Trichobilharzia sp., Apatemon sp., Pegosomum sp., Petasiger sp., Echinostoma revolutum and Plagiorchis sp. These findings emphasize the occurrence and diversity of trematode cercariae among naturally infected lymnaeid snails in Phayao province and could contribute to broadening our understanding of the host-parasite relationships between trematodes and their first intermediate hosts as well as developing effective interventions to control trematode parasitic diseases.

Population Dynamics of <i>Helicoverpa armigera</i> (Hubner) and its Parasitization by <i>Campoletis chlorideae</i> Uchida in Chickpea

Experiments were conducted on three dates of sowing i.e., 20th October, 15th November and 1st December during 2018-19 and 2019-20 at Banda to assess the population dynamics of gram pod borer Helicoverpa armigera (Hubner) and % larval parasitization in chickpea. The incidence of H. armigera was noticed from 49th to 12th Standard Meteorological Week (SMW). Its incidence was increased at vegetative stage from 50th to 1st SMW in first date of sown crop and at reproductive stage from 10th to 12th SMW in 3rd date of sown crop. The highest and lowest parasitization of larvae by Campoletis chlorideae were recorded as 58.67 and 55.00% (49th SMW) and 10.67% (12th SMW) and 7.30% (13th SMW) during 2018-19 and 2019-20, respectively. Maximum and minimum temperature showed a negatively by significant correlation with larval parasitization whereas, relative humidity and rainfall had a positively non-significant correlation.

Microbial food safety of lettuce produced under irrigated wastewater from Onyasia River in Ghana

Fresh produce continues to be the main source of foodborne illness outbreaks, particularly in developing countries where water stress results in the use of surface wastewater all year round for irrigation of vegetables. The objective of the current study was to evaluate the microbial quality of lettuce irrigated with wastewater from Onyasia river. Lettuce and soil were sampled from selected vegetable farms on the Eastern gate of the Ghana Atomic Energy Commission land alongside surface wastewater from the Onyasia river, which is used as the main source for irrigation. Samples were analyzed for aerobic mesophilic plate counts, total coliforms count, fecal coliforms count, Salmonella counts and intestinal parasites using standard methods. Surface wastewater was found to be contaminated with mean fecal coliform counts of log 3.50 cfu/100 mL. Enterobacter cloacae, Acinetobacter baumannii, and Klebsiella pneumonia were also isolated from the wastewater samples. No intestinal parasite egg was detected in wastewater samples. While fecal coliforms and Salmonella spp were not detected, mean aerobic mesophilic plate counts (log 4.82 cfu/g) and total coliforms count (log 3.50 cfu/g) were recorded in the lettuce samples. Enterobacter asburiae, Acinetobacter baumannii, Klebsiella variicola and Citrobacter freundii were isolated from lettuce. Infective larvae of helminths were observed on lettuce samples at a density of 36/g-648/g with a mean of 342/g. Soil samples recorded a mean aerobic mesophilic plate counts of log 6.14 cfu/g, total coliforms count of log 4.90 cfu/g while fecal coliforms and Salmonella spp were not detected (<1 cfu/g) Soil samples yielded a mean infective larval count of 1941.5 larvae/g and a Strongyle count of 12 eggs/g. Even though less than 1 cfu/g of Salmonella spp were found, the study found lettuce to be contaminated with other foodborne bacteria pathogens, opportunistic bacteria pathogens, eggs and infective larvae of intestinal parasites of health importance. As a consequence, the microbial food safety risk associated with wastewater irrigated vegetables was observed to be high with possible public health implications. It is recommended that wastewater from the Onyasia River should be treated before use for irrigation of lettuce.

A member of the CAP protein superfamily, Hc-CAP-15, is important for the parasitic-stage development of Haemonchus contortus

BackgroundThe CAP superfamily proteins are distributed widely in eukaryotes and play crucial roles in various biological processes. However, very little is known about their functions in parasitic nematodes, including Haemonchus contortus, a socioeconomically important parasitic nematode. We have therefore studied a member of the CAP protein family of H. contortus, named Hc-CAP-15, with the aim to explore its roles in regulating the parasitic developmental process.MethodsThe conservation and phylogenetic relationships, spatial expression and temporal transcription profiles of Hc-CAP/cap-15, as well its biological function during parasite development were investigated using bioinformatics, immunofluorescence, real-time PCR and RNA interference (RNAi).ResultsHc-CAP-15 was found to be a single-domain CAP protein consisting of four conserved motifs that is localized in the cuticle, intestine and oocyte of adult worms. Hc-cap-15 was transcribed at all developmental stages of H. contortus, with the highest transcription level in parasitic fourth-stage larvae (L4s). Silencing of Hc-cap-15 resulted in a significant increase in the body length of L4s.ConclusionsThe results suggested that Hc-CAP-15 is important for the development of H. contortus. Our findings provide a basis for further study of the functions of the CAP family proteins in H. contortus and related parasitic nematodes.Graphical

The lepidopteran pest complex infesting menthol mint in India: Distribution during the crop development, species composition and associated parasitoids

Menthol mint, Mentha arvensis L. is an important aromatic and medicinal herb cultivated as an industrial crop for its essential oil in the Indo-Gangetic plains of India. The commercial production of menthol mint suffers due to defoliation caused by lepidopteran pests and currently becoming a serious constraint for its clean cultivation. The information on occurrence of lepidopteran caterpillars defoliating menthol mint in the region is limited. In this study, we assessed the occurrence and injury caused by lepidopteran pests from seven major menthol mint growing districts of the Indo-Gangetic plains of India. Further, the species composition of lepidopteran pests and their associated parasitoids were also reported. The survey revealed that seven lepidopteran pest infestations were recorded on different phenological growth stages of menthol mint in the Indo-Gangetic plains of India. The larval population density of lepidopteran pests was significantly different between the districts, species and phenological stages of menthol mint. The larval population density of the lepidopteran pest varied between 0.41 ± 0.31 to 2.37 ± 1.43 larvae/m2 across the locations. The higher occurrence of Spodoptera litura (Fabricius), Spilarctia obliqua Walker and Thysanoplusia orichalcea (Fabricius) was recorded in menthol mint. The higher incidence of lepidopteran pests was recorded at the mid-vegetative growth stage of menthol mint. This study found eight parasitoids parasitizing egg and larval stages of lepidopteran pests. The parasitism rate of egg parasitoids, Trichogramma chilonis Ishii and Trichogramma achaeae Nagaraja and Nagarkatti was 23.53–35.31% and 27.78% to the eggs of Helicoverpa armigera and T. orichalcea, respectively. The larval parasitoids caused a total of 5.78% larval parasitism to the various lepidopteran pests of menthol mints. This information provides a current pest status of lepidopteran pests infesting menthol mint in Indo-Gangetic plains of India. This baseline information could be used for the development of management strategies against lepidopteran pests for sustainable menthol mint production.

Immune markers in goats selected for reduced gastrointestinal nematode egg count under artificial infection conditions

This study aimed to further investigate the mechanisms responsible for inhibition of gastrointestinal nematode egg production in a line of Scottish Cashmere Goat selected for low faecal egg count. Animals were chosen as the lowest egg producers from a line selected for low egg output (selected group) with a second group from the wider herd based on high faecal egg count as controls. All animals were artificially infected with Teladorsagia circumcincta and Trichostrongylus vitrinus, then treated with anthelmintic and challenge infected prior to euthanasia and post mortem sampling.There was no effect on body weight between groups at any point in the study. Mean faecal egg count was reduced by 68 % in the selected group when compared with the controls. Circulating eosinophil counts were consistently elevated in the selected group, but this was only marginally significant (P = 0.045). Most of the circulating and tissue antibodies (IgG, IgA and IgE) measured were slightly elevated in the selected group but not significantly. Mucosal mast cells, eosinophils and globule leukocyte levels were higher in the abomasal and intestinal tissues in selected animals. Following challenge infection there was no difference in numbers of parasites, however there were more early stage parasite larvae and fewer late stage larvae in the both the abomasum and duodenum of the selected group compared with the unselected group, indicating some inhibition of parasite development.Overall, the study further demonstrated that selection based on low egg count has resulted in a line of goats producing significantly fewer parasites under identical infection with no effect on bodyweight. This appears to be associated with elevation in antibody and effector cells. Some evidence of host inhibition of parasite development was observed in the selected animals.

DNA sequencing confirms meningeal worm (Parelaphostrongylus tenuis) and muscle worm (Parelaphostrongylus andersoni) in white-tailed deer (Odocoileus virginianus): Implications for moose (Alces alces) management.

In North America, some moose populations are declining, and meningeal worm (Parelaphostrongylus tenuis) infections may be contributing. Moose are aberrant hosts for meningeal worm and develop severe pathology whereas white-tailed deer (WTD) are definitive hosts that experience minimal pathology and spread parasite larvae into the environment. Analyses of harvested WTD heads confirmed meningeal worm in Western Manitoba, Canada including in areas where moose have experienced population declines and are currently of management concern. The prevalence of larval meningeal worm from WTD feces in these areas are unknown, particularly because the dorsal-spined larvae (DSL) are morphologically indistinguishable from muscle worm (Parelaphostrongylus andersoni). To assess transmission risk of DSL, we investigated the spatial and temporal variation of prevalence in WTD feces from four areas (two with historical moose population declines and two without) sampled across two summers. We predicted higher prevalence of DSL in areas where moose are of management concern and surveys have shown higher meningeal worm prevalence in WTD heads. Further, we expected to only recover meningeal worm, as muscle worm has only been reported from caribou in more northern areas of Manitoba. We collected WTD feces by transect sampling, used the Baermann technique to obtain larvae, and sequenced partial cytochrome oxidase 1 and internal transcribed spacer 2 genes to confirm species identity. Zero-inflated models revealed that DSL prevalence did not differ temporally but was higher in areas where moose are of management concern. Genetic analyses revealed that meningeal worm and muscle worm were both present in Western Manitoba and co-occurred in three areas. Our results reveal novel insights into the geographic distribution of muscle worm and emphasize the importance of DNA sequencing for DSL identification. We suggest that concern for moose populations is warranted given the increased risk of parasite infection in some management areas.