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Communication Dans Un Congrès Année : 2018

Time-dependent effects of two fungicides and their mixture on enchytraeid and earthworm communities under field conditions

Résumé

According to the current regulation for the registration of plant protection products on the market, the environmental risk assessment of pesticide use is generally performed under laboratory conditions. Very little information is available in natura,where multiple stresses occur. In this study, we assessed the effects of two commercial formulations of fungicides, i.e., Cuprafor Micro® (composed of 500 g.kg-1 copper oxychloride) and Swing Gold® (composed of 50 g.l-1 epoxiconazole and 133 g.l-1 dimoxystrobin), and the mixture of both on two groups of terrestrial oligochaetes (Lumbricidae and Enchytraeidae) after 1, 6 and 12 months (i.e., t1, t6 and t12) of exposure under field conditions. We also assessed the feeding activity of soil organisms using the bait lamina method. Our results showed a lower Shannon index for earthworms in the treatment with the mixture of both pesticides (i.e., 1,5 l. ha-1 of Swing Gold® and 4 kg.ha-1 of copper) and in the treatment with the Swing Gold® at ten times the recommended dose (i.e., 15 l. ha-1) after one and six months. We also found a lethal effect of Swing Gold® on anecic earthworms at t1, while an effect of copper on annelids at ten times the recommended dose (40 kg.ha-1 of copper) was observed later at t12. We showed no overall significant difference in total feeding activity, enchytraeid density and diversity between treatments with or without pesticide at different sampling periods. In the Swing Gold® treatment, earthworm community did not recover twelve months after pesticide application. We suggest thus going beyond the ISO norm 11268-3 (2014) - for the study of the effects of pollutants on earthworms under field conditions - by studying Oligochaeta community and other functional endpoints (e.g. organic matter decomposition with the tea bag method) over two years to better assess environmental risks of plant protection product use and their mixture. Keywords: Cuprafor Micro®, Swing Gold®, agroecosystems, feeding activity 557 Toxicity of imidacloprid and thiacloprid towards four Collembolan species C. Lima, Vrije Universiteit Amsterdam / Animal Ecology; C. van Haren, G. Mainardi, Vrije Universiteit Amsterdam / Department of Ecological Science; C. van Gestel, Vrije Universiteit Amsterdam / Ecological Science Folsomia candida has been used for assessing the toxicity towards non-target soil invertebrates since the 1960s, but only in the 1990s a standard reproduction test was developed. In 2009, after a ring test, OECD also accepted Folsomia fimetaria as a model organism The first species, has been transported all over the world, therefore being considered a tramp species, having a parthenogenetic mode of reproduction. F. fimetaria is present in most of natural and agricultural soils worldwide, and has a sexual mode of reproduction. Following a suggestion of the ring test to use different species of springtails to assess the toxicity of contaminants, in this study two additional species, Heteromurus nitidus and Sinella curviseta, were used together with F. candida and F. fimetaria to determine the toxicity of imidacloprid and thiacloprid in Lufa 2.2 soil. The tests aimed at answering 2 main questions: (i) Is there a difference in the sensitivity to neonicotinoids between the different species?; (ii) Are these species suitable for assessing the toxicity of neonicotinoids? Imidacloprid was most toxic, with F. fimetaria presenting around the same sensitivity as F. candida for survival (LC50 0.56 mg/kg dry Lufa 2.2 soil), and a slight difference in the sensitivity for reproduction, with EC50s for F. fimetaria of 0.10 mg/kg dry soil and for F. candida of 0.26 mg/kg dry soil. H. nitidus was slightly less sensitive with an LC50 of 1.6 mg/kg dry soil and an EC50 of 0.40 mg/kg dry soil. Thiacloprid was tested on S. curviseta, F. candida and H. nititdus, with survival of the first one being least sensitive (LC50 27 mg/kg dry soil), followed by F. candida (LC50 5.2 mg/kg dry soil) and H. nitidus being the most sensitive with an LC50 of 2.3 mg/kg dry soil. Thiacloprid was more toxic to the reproduction of S. curviseta (EC50 2.6 mg/kg dry soil) followed by F. candida (EC50 1.5 mg/kg dry soil), and H. nitidus (EC50 1.3 mg/kg dry soil). The different species tested presented similar sensitivity towards the neonicotinoids for both endpoints, with the exception of S. curviseta. The results suggest a specific mode of action of thiacloprid towards reproduction, a trend that has been found in all tests, except for of H. nitidus that presented around the same sensitivity to both survival and reproduction. The species tested presented good control performance and consistency in the results, pointing towards a possibility to be used in toxicity tests.
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Dates et versions

hal-01804598 , version 1 (31-05-2018)

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  • HAL Id : hal-01804598 , version 1
  • PRODINRA : 420669

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Joël Amossé, Sylvain Bart, Céline Pelosi, Pauline Thiel, Alexandre R.R. Pery. Time-dependent effects of two fungicides and their mixture on enchytraeid and earthworm communities under field conditions. SETAC Europe 28th Annual Meeting, May 2018, Rome, Italy. ⟨hal-01804598⟩
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