Abstract

BackgroundAlthough debates about the assessment of potential effects of pesticides on amphibians are ongoing, amphibians are not yet considered in the current EU environmental risk assessment of pesticides. Instead, the risk assessment of potential effects on aquatic amphibian life stages relies on use of data of surrogate species like the standard temperate fish species rainbow trout (Oncorhynchus mykiss). This assumption is mainly based on the comparison to amphibian species not native to Europe such as the aquatic African clawed frog (Xenopus laevis). It remains unclear whether these surrogate species cover semi-aquatic Central European amphibian sensitivities. Therefore, we assessed the acute sensitivity of aquatic stages of eight European amphibian species native in Germany (Bufo bufo, Bufotes viridis, Epidalea calamita, Hyla arborea, Pelobates fuscus, Pelophylax sp., Rana dalmatina, R. temporaria) towards commercial formulations of the fungicide folpet (Folpan® 500 SC, Adama) and the insecticide indoxacarb (Avaunt® EC, Cheminova). The determined acute sensitivities (median lethal concentration, LC50) were included in species sensitivity distributions and compared to experimentally determined LC50 values of X. laevis and literature values of O. mykiss.ResultsThe results showed that native amphibian sensitivities differed between the tested pesticides with a factor of 5 and 11. Depending on the pesticide, X. laevis was five and nine times more tolerant than the most sensitive native amphibian species. Comparing literature values of O. mykiss to the experimentally determined sensitivities of the native amphibian species showed that the O. mykiss sensitivity was in the same range as for the tested amphibians for the formulation Folpan® 500 SC. The comparison of sensitivities towards the formulation Avaunt® EC showed an eight times lower sensitivity of O. mykiss than the most sensitive amphibian species.ConclusionsA risk assessment using the 96-h LC50 values for fish covers the risk for the assessed aquatic stages of European amphibians after the application of the recommended uncertainty factor of 100 and thus may be adequate for lower tier risk assessment of the studied pesticides. If aquatic amphibian testing will be required for pesticide risk assessment nevertheless, acute tests with the model organism X. laevis and the application of an appropriate uncertainty factor might be a promising approach.

Highlights

  • Debates about the assessment of potential effects of pesticides on amphibians are ongoing, amphibians are not yet considered in the current European Union (EU) environmental risk assessment of pesticides

  • Sensitivity towards the pesticide formulation Folpan varied between all tested amphibian species in the decreasing order Pelophylax sp. > Rana temporaria > Bufotes viridis = Epidalea calamita = Pelobates fuscus > Hyla arborea > Rana dalmatina = Xenopus laevis = Bufo bufo (“ > ” denotes significant difference, “ = ” denotes no difference; Additional file 5: Table S4)

  • Sensitivities towards Avaunt decreased in the order Bufo bufo > Epidalea calamita > Rana dalmatina > Hyla arborea = Rana temporaria = Bufotes viridis > Pelobates fuscus > Xenopus laevis > Pelophylax sp. and ranged from 0.86 to 9.43 mg Avaunt/L, revealing 11-fold

Read more

Summary

Introduction

Debates about the assessment of potential effects of pesticides on amphibians are ongoing, amphibians are not yet considered in the current EU environmental risk assessment of pesticides. The risk assessment of potential effects on aquatic amphibian life stages relies on use of data of surrogate species like the standard temperate fish species rainbow trout (Oncorhynchus mykiss). This assumption is mainly based on the comparison to amphibian species not native to Europe such as the aquatic African clawed frog (Xenopus laevis). The majority of these comparisons is based on pesticides that are no longer commonly used in the EU (e.g., DDT, atrazine, carbaryl or chlorinated pesticides like chlorpyrifos and lindane) Many of these studies focus on model species not native to Europe such as North American species or (sub-) tropical species like the African clawed frog (Xenopus laevis). It remains unclear whether the sensitivity of tadpoles of the aquatic species X. laevis to pesticides is protective for semi-aquatic species native in Europe [27]

Objectives
Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call