Toxicity of ivermectin residues in aged farmyard manure to terrestrial and freshwater invertebrates

Bryony Sands, Madeleine Noll

Research output: Contribution to journalArticle (Academic Journal)peer-review

1 Citation (Scopus)


1. Farmyard manure is often stored, aged and spread on fields as fertiliser;
however, dung may be contaminated with residues of veterinary endectocides used to treat livestock for parasites. The persistence of these chemicals during storage and impact on invertebrate biodiversity after spreading are not well understood.
2. This study considered whether residues in aged cattle manure could have impacts on terrestrial and freshwater invertebrate biodiversity and ecosystem function.
3. Fresh cattle dung was spiked with known concentrations of the endectocide ivermectin or an excipient only (control) and aged in the field for 4 months between February and May 2020. Each month rainwater run-off was collected and used to examine toxicity using the freshwater invertebrate Daphnia magna. In June 2020, manure was spread on mesocosms containing topsoil, and above-ground insect emergence, soil fauna feeding rate, earthworm abundance and pasture productivity (perennial ryegrass growth), were measured over 10 weeks.
4. Rainwater-runoff from manure contaminated with ivermectin was highly toxic
(60–100% mortality) to D. magna for the entire 4 months of storage. Coleoptera and Diptera emergence was lower from mesocosms spread with ivermectin-contaminated manure compared with control manure. Pasture productivity was significantly lower (18–20%) in mesocosms spread with ivermectin-contaminated manure.
5. The results indicate that ivermectin residues aged manure have the potential to
retain toxic effects on terrestrial and freshwater invertebrates for at least 4 months of storage, could reduce pasture productivity, and may have pervasive impacts on invertebrate biodiversity in agricultural systems.
Original languageEnglish
JournalInsect conservation and diversity
Publication statusPublished - 14 Aug 2021

Bibliographical note

Funding Information:
The authors would like to thank Shuhan Shi and Chenxi Zhou for helping with the toxicity assays, Richard Wall for taxonomic assistance, Andrew Hughes for practical assistance and the three farmers who supplied cattle dung. This work was supported by the Bristol Centre for Agricultural Innovation (BCAI). Daphnia magna

Publisher Copyright:
© 2021 Royal Entomological Society.


  • agriculture
  • agrochemicals
  • biodiversity
  • Coleoptera
  • Daphnia magna
  • Diptera
  • environmental pollution
  • pasture productivity
  • veterinary parasiticides


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