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

Abstract

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.

Is qualitative and quantitative metabarcoding of dung fauna biodiversity feasible?

“…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 ).…”

“…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).…”

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

“…Results were generally consistent across countries and support formal adoption of the method by the European Union to assess the effects of veterinary medical product residues on the composition and diversity of insects occurring in dung of treated livestock. Other studies in the present special section, Effects of Ivermectin , report the concentrations of residues detected in dung used for the present study , the effect of these residues on soil organisms , and the effect of these residues on community function (dung degradation ).…”

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

“…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.…”

“…Although pronounced effects of residue were detected on the coprophilous community, Tixier et al, found no significant effects of residue on dung degradation at any of the 4 study sites (absolute degradation time differed, probably because of climate: dung was degraded much faster at the “moist” sites [Wageningen, Zurich] than at the dry sites [Lethbridge, Montpellier]). These 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.…”