Endoparasite control strategies: implications for biodiversity of native fauna

The serodiagnostic potential of recombinant proteins TES-30 and TES-120 in an indirect ELISA in the diagnosis of toxocariasis in cattle, horses, and sheep

Toxocariasis is a zoonotic disease that affects humans and animals alike. Although recombinant proteins are widely used for its diagnosis in humans, their performance in companion and production animals remains unknown. This study aimed to investigate the serodiagnostic potential of the recombinant proteins rTES–30 and rTES–120 from Toxocara canis in an indirect ELISA for cattle, horses, and sheep. Serum samples collected from the animals were tested with indirect ELISA and Western Blotting using T. canis TES–30 and TES–120 recombinant proteins produced in Escherichia coli, as well as native-TES. In the ELISA, rTES–30 showed high serodiagnostic potential in sheep and horses (92.6% and 85.2%, respectively), while the sensitivity of rTES–120 was higher in cattle and horses (97.2% and 92.6%, respectively). Furthermore, a highly positive association was observed between native and recombinant proteins in seropositive samples, while a moderately positive association was observed in seronegative samples, probably due to the lower specificity of native TES. In conclusion, our study indicates that the use of recombinant proteins in an indirect ELISA is an effective tool for the serodiagnosis of toxocariasis in animals, with the choice of protein being species-dependent.

Climate Extremes, Vegetation Change, and Decoupling of Interactive Fire-Grazing Processes Exacerbate Fly Parasitism of Cattle

We assessed local horn fly (Haematobia irritans L.) and face fly (Musca autumnalis De Geer) communities on cattle in 2012 and 2013 relative to vegetation and climate data to understand how parasitism of cattle is influenced by change in climate and vegetation structure. We compared heterogeneity management using spatially and temporally discrete fires (i.e., patch-burning one-third of a pasture annually) to homogeneity management (i.e., burning entire pasture in 2012 then no burning in 2013), with cattle grazing all years in both treatments. Predicted emergence of horn flies and face flies was 24 and 34 d earlier in 2012 associated with earlier spring warming, a significant deviation from the five-year mean. Intraannual horn fly dynamics were explained by concurrent high ambient air temperature the day of observations, but face flies were explained by low ambient air temperatures and dry conditions 3 wk before observations. Importance values of information for the theoretic models including fire treatments ranged from 0.89 to 1, indicating that both horn flies and face flies are sensitive to habitat alterations and fire-driven animal movements. Ordination indicates herds on unburned pastures were dissimilar to herds on pastures burned with patchy fires or pastures burned completely and species-specific fly responses to different vegetation structure metrics. For example, horn flies were correlated with vegetation visual obstruction, and face flies were correlated with woody plant cover. Vegetation structure may be as important as climate in driving the dynamics of fly parasites of cattle.

Anuran helminth communities from contrasting nature reserve and pasture sites in the Pantanal wetland, Brazil

Studies of amphibian macroparasites are relevant for the investigation of parasite community ecology and disease dynamics. Here, the parasite communities of five anuran species (Hypsiboas raniceps, Phyllomeduza azurea, Pseudis paradoxa, Leptodactylus fuscus and Leptodactylus podicipinus) are described from two habitats with different levels of preservation (pasture versus nature reserve). Specifically, we used mixed-effect models to test whether helminth species richness, prevalence and abundance differ between the two host collection sites. A total of 120 anuran individuals and 25 helminth parasite taxa were collected. Helminth communities differed between collection sites and among host species. In general, helminth species richness, prevalence and abundance were higher in hosts collected in the pond from the nature reserve. In all, these data help fill the gap in parasite biodiversity knowledge in a changing area, within a sensitive group of vertebrate hosts.

Impacts of Pharmaceuticals on Terrestrial Wildlife

Essentially ubiquitous in our environment, residues of human and veterinary pharmaceuticals somewhat paradoxically represent an emerging and increasing risk to wild biota. Whilst in recent years a great deal of analytical effort has been expended to quantify the presence of many pharmaceutical contaminants, especially in freshwater systems, our real understanding of the risks posed to most clades of wildlife, aquatic and terrestrial alike, still lags behind. In particular, relevant field-based studies regarding possible chronic impacts in higher terrestrial wildlife (birds, mammals, reptiles, etc.) remain all too scarce. Yet, for example, over the past two decades Old World Gyps vultures on the Indian subcontinent have been virtually extirpated due to non-target exposure to a single synthetic pharmaceutical compound, diclofenac (a non-steroidal anti-inflammatory drug). Here, we highlight and discuss the myriad possible exposure routes to terrestrial wildlife, consider the analytical and monitoring approaches that are already in use or that could be used in future research, and reflect upon a selection of legislative approaches currently being applied to identified terrestrial impacts. Finally, with the ultimate aim of encouraging further applied ecotoxicology-based research in this emerging field, we highlight several priorities for future inquiry, with special emphasis on non-target effects in previously overlooked but potentially vulnerable or highly representative clades of wildlife exposed within environmentally relevant, real-world scenarios.

Neglected wild life: Parasitic biodiversity as a conservation target

Parasites appropriate host resources to feed and/or to reproduce, and lower host fitness to varying degrees. As a consequence, they can negatively impact human and animal health, food production, economic trade, and biodiversity conservation. They can also be difficult to study and have historically been regarded as having little influence on ecosystem organization and function. Not surprisingly, parasitic biodiversity has to date not been the focus of much positive attention from the conservation community. However, a growing body of evidence demonstrates that parasites are extremely diverse, have key roles in ecological and evolutionary processes, and that infection may paradoxically result in ecosystem services of direct human relevance. Here we argue that wildlife parasites should be considered meaningful conservation targets no less relevant than their hosts. We discuss their numerical and functional importance, current conservation status, and outline a series of non-trivial challenges to consider before incorporating parasite biodiversity in conservation strategies. We also suggest that addressing the key knowledge gaps and communication deficiencies that currently impede broad discussions about parasite conservation requires input from wildlife parasitologists.

Wild animal conservation and welfare in agricultural systems

At least one-third of the land on earth is used for agricultural production and conflicts with the interests of wildlife are inevitable. These conflicts are likely to escalate as the human population expands and as the scale and intensity of agricultural production increases. This paper argues that the same underlying causes frequently affect both wild animal welfare and conservation. Three key threats are discussed: disease transmission from domestic animals and the interventions used to manage wildlife reservoirs of zoonotic diseases; physical operations such as harvesting and the conversion of wildlife habitat to farmland; and the use of agrochemicals, particularly for pest control. While direct effects, such as accidental poisoning, tend to attract the most public attention, it is argued that indirect effects, such as the reduction in food supplies or the disruption of social structures, are likely to be of greater importance. The suffering of pest animals has traditionally been undervalued. There is a need for broader adoption of integrated, ecologically based strategies which minimise suffering and also minimise the numbers of animals involved by preventing population resurgence. New research is urgently required to compare the effects of alternative, economically viable farming strategies on both wildlife conservation and welfare, possibly within the framework of ecosystem services assessments.

The effect of praziquantel applied per os on selected haematological and biochemical indices in common carp (Cyprinus carpio L.)

The aim of the study was to assess the effects of the anthelminthic, praziquantel, on the haematological and biochemical indices of the blood of common carp (Cyprinus carpio L.). Fish were divided into six groups: two groups received 30 mg kg(-1) body weight (bw) of praziquantel, and two groups were given 50 mg kg(-1) bw of praziquantel mixed into the heat-treated amyloid vehicle. Fish in the remaining two groups were given only the amyloid vehicle and were used as controls. Fish were examined either 24 or 96 h after administration. Praziquantel treatment was characterised by a significantly lower erythrocyte count, haemoglobin level, packed cell volume and total protein at both dose levels after 24 h compared with the controls, but these parameters were similar to the control values at 96 h. The activity of alanine aminotransferase (ALT) was significantly higher after 96 h in the treated groups, which could be attributed to slight hepatocyte damage caused by praziquantel. However, the differences between the treated and the control groups were not great, and we presumed that they were reversible.

Unravelling causality from correlations: revealing the impacts of endemic ectoparasites on a protected species (tuatara)

Understanding the impacts of endemic parasites on protected hosts is an essential element of conservation management. However, where manipulative experiments are unethical, causality cannot be inferred from observational correlative studies. Instead, we used an experimental structure to explore temporal associations between body condition of a protected reptile, the tuatara (Sphenodon punctatus) and infestation with ectoparasites (ticks and mites). We surveyed tuatara in a mark-recapture study on Stephens Island (New Zealand), which encompassed the pre-peak, peak and post-peak infestation periods for each ectoparasite. Tick loads during the peak infestation period were negatively related to body condition of tuatara. Body condition before the peak was not related to subsequent infestation rates; however, tick loads in the peak were negatively related to subsequent changes in body condition. Mite loads during the peak infestation period were not correlated with body condition of tuatara. Body condition before the peak had no effect on subsequent mite infestation rates, but mite loads of small males during the peak were negatively related to subsequent changes in body condition. Our results suggest that both ectoparasites reduce the body condition of tuatara, which has implications for the long-term conservation management of this host and its parasites.

Parasitic nematodes - from genomes to control

The diseases caused by parasitic nematodes in domestic and companion animals are major factors that decrease production and quality of the agricultural products. Methods available for the control of the parasitic nematode infections are mainly based on chemical treatment, non-chemical management practices, immune modulation and biological control. However, even with integrated pest management that frequently combines these approaches, the effective and long-lasting control strategies are hampered by the persistent exposure of host animals to environmental stages of parasites, the incomplete protective response of the host and acquisition of anthelmintic resistance by an increasing number of parasitic nematodes. Therefore, the challenges to improve control of parasitic nematode infections are multi-fold and no single category of information will meet them all. However, new information, such as nematode genomics, functional genomics and proteomics, can strengthen basic and applied biological research aimed to develop improvements. In this review we will, summarize existing control strategies of nematode infections and discuss ongoing developments in nematode genomics. Genomics approaches offer a growing and fundamental base of information, which when coupled with downstream functional genomics and proteomics can accelerate progress towards developing more efficient and sustainable control programs.

Cow-dung colonization and decomposition following insect exclusion

The rate of dung-pat degradation in cattle pastures in south west England was examined between May and September 2002, using batches of standardized, 1.5 kg, artificially-formed cow pats. In pats in which insects were allowed free access, the rate of disappearance, measured as ash-free dry weight, was faster in spring than summer and the loss of organic matter ranged between 0.69 and 1.99% per day, equating to an estimated time for complete disappearance of 57-78 and 88-111 days in spring and summer, respectively. To assess the role of colonizing insects on decomposition, six batches of pats were constructed and either left uncovered or, using fine mesh cages, were covered for 2, 7 or 14 days following deposition to exclude colonizing insects, after which they were uncovered. After 35 days all pats were then retrieved from the field, the composition of the invertebrate community within each pat was determined and the degree of degradation, measured as ash-free dry weight, was assessed. Covered pats had significantly higher rates of ash-free dry weight loss than uncovered pats. From the 180 pats that were recovered and searched, larvae of Aphodius (Coleoptera: Scarabaeidae) were the most numerous taxon collected (1435 individuals). Aphodius larvae were significantly more abundant in pats that remained uncovered or were covered for 2 days only, compared to pats that had been covered for 7 or 14 days. The results show that the exclusion of insects for as little as two days following deposition causes a significant reduction in both the insect population and the subsequent rate of pat degradation.