Validation of a standard field test method in four countries to assess the toxicity of residues in dung of cattle treated with veterinary medical products

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By degrading the dung of livestock that graze on pastures, coprophilous arthropods accelerate the cycling of nutrients to maintain pasture quality. Many veterinary medicinal products, such as ivermectin, are excreted unchanged in the dung of treated livestock. These residues can be insecticidal and may reduce the function (i.e., dung-degradation) of the coprophilous community. In the present study, we used a standard method to monitor the degradation of dung from cattle treated with ivermectin. The present study was performed during a 1-yr period on pastures in Canada, France, The Netherlands, and Switzerland. Large effects of residue were detected on the coprophilous community, but degradation of dung was not significantly hampered. The results emphasize that failure to detect an effect of veterinary medicinal product residues on dung-degradation does not mean that the residues do not affect the coprophilous community. Rather, insect activity is only one of many factors that affect degradation, and these other factors may mask the nontarget effect of residues. Environ Toxicol Chem 2016;35:1953-1958. © 2015 SETAC.

Section: Resultscontrasting

confidence: 95%

A four‐country ring test of nontarget effects of ivermectin residues on the function of coprophilous communities of arthropods in breaking down livestock dung

Tixier

Blanckenhorn²,

Lahr³

et al. 2016

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“…However, the species richness present and that barcoded do correlate positively (Table ; r = 0.63) and have similar coefficients of variation, so the type II error was roughly similar in all samples. Because biodiversity assessments in the present study and other contexts typically compare various samples across populations or treatments (in the present special section livestock medication levels ), detection of differences between them might therefore not be strongly affected by inflated barcoding richness (assuming no systematic biases). On the other hand, the barcoding diversity index was actually lower than the actual species diversity of the samples when based on the relative abundances of raw reads for all hits, but higher when based on the decadic logarithm of these relative abundances (Table ).…”

Section: Resultsmentioning

confidence: 97%

“…In recent years, an international consortium of practitioners and regulators has been involved in investigating the validity of higher‐tier ecotoxicological field tests. Such assessments of the entire dung biodiversity were in principle found to be repeatable and hence feasible in practice and are reported in this special section . The present study involved processing thousands of adult insect specimens that emerged from experimental dung pats, which were identified to various taxonomic levels (species, genera, family).…”

Section: Introductionmentioning

confidence: 99%

Is qualitative and quantitative metabarcoding of dung fauna biodiversity feasible?

Blanckenhorn¹,

Rohner²,

Bernasconi

et al. 2016

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In biodiversity assessments, especially of small-bodied organisms for which taxonomic expertise is lacking, identification by genetic barcoding may be a cost-effective and efficient alternative to traditional identification of species by morphology, ecology, and behavior. The authors tested the feasibility and accuracy of such an approach using dung insects of practical relevance in ecotoxicological assessments of veterinary pharmaceutical residues in the environment. They produced 8 known mixtures that varied in absolute and relative composition of small-bodied and large-bodied species to see whether mitochondrial cytochrome c oxidase subunit 1 barcoding picks up all species qualitatively and quantitatively. As demonstrated before in other contexts, such metabarcoding of large numbers of dung insect specimens is principally possible using next-generation sequencing. The authors recovered most species in a sample (low type I error), at minimum permitting analysis of species richness. They obtained even quantitative responses reflecting the body size of the species, although the number of specimens was not well detected. The latter is problematic when calculating diversity indices. Nevertheless, the method yielded too many closely related false positives (type II error), thus generally overestimating species diversity and richness. These errors can be reduced by refining methods and data filtering, although this requires bioinformatics expertise often unavailable where such research is carried out. Identification by barcoding foremost hinges on a good reference database, which does not yet exist for dung organisms but would be worth developing for practical applications. Environ Toxicol Chem 2016;35:1970-1977. © 2015 SETAC.

“…Suggested decision flowchart for assessing the risk of veterinary medicinal products for the structure and functions of dung and soil organisms using the structural (see Floate et al ) and functional (see Tixier et al ) approaches developed in the present project and defined in the present special section for higher‐tier risk assessment.…”

Section: Discussionmentioning

confidence: 99%

Effects of ivermectin application on the diversity and function of dung and soil fauna: Regulatory and scientific background information

Adler

Bachmann

Blanckenhorn³

et al. 2016

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The application of veterinary medical products to livestock can impact soil organisms in manure-amended fields or adversely affect organisms that colonize dung pats of treated animals and potentially retard the degradation of dung on pastures. For this reason, the authorization process for veterinary medicinal products in the European Union includes a requirement for higher-tier tests when adverse effects on dung organisms are observed in single-species toxicity tests. However, no guidance documents for the performance of higher-tier tests are available. Hence, an international research project was undertaken to develop and validate a proposed test method under varying field conditions of climate, soil, and endemic coprophilous fauna at Lethbridge (Canada), Montpellier (France), Zurich (Switzerland), and Wageningen (The Netherlands). The specific objectives were to determine if fecal residues of an anthelmintic with known insecticidal activity (ivermectin) showed similar effects across sites on 1) insects breeding in dung of treated animals, 2) coprophilous organisms in the soil beneath the dung, and 3) rates of dung degradation. By evaluating the effects of parasiticides on communities of dung-breeding insects and soil fauna under field conditions, the test method meets the requirements of a higher-tier test as mandated by the European Union. The present study provides contextual information on authorization requirements for veterinary medicinal products and on the structure and function of dung and soil organism communities. It also provides a summary of the main findings. Subsequent studies on this issue provide detailed information on different aspects of this overall project. Environ Toxicol Chem 2016;35:1914-1923. © 2015 SETAC.