The impact of the fungicide fenpropimorph (Corbel®) on bacterivorous and fungivorous protozoa in soil

Abstract

Summary 0[ The ability of indigenous soil protozoa to survive and multiply when exposed to various concentrations of the fungicide fenpropimorph was investigated[ The number of protozoan taxa in relation to biocide concentration was examined in enrichment cultures[ The population dynamics of bacterivorous and fungivorous protozoa\ hyphal forming units\ and respiration activity were followed in soil microcosms amended with glucose and various concentrations of fenpropimorph[ 1[ The average number of~agellate taxa detected in 49!mg portions of air!dried soil declined from 01 to zero with fenpropimorph concentrations increasing from 9 to 59 mg L Ð0 [ Naked amoebae and ciliates were present at all fenpropimorph concen! trations[ The 49!mg soil portions initially contained 0=8 × 09 2 heterotrophic~agel! lates\ 0=3 × 09 2 naked amoebae and about 4 ciliates[ The presence of the two latter groups even at concentrations of 59 mg L Ð0 therefore suggests that they are more tolerant to fenpropimorph than the soil~agellates[ 2[ The addition of glucose had a strong stimulatory e}ect on soil respiration\ which lasted for about 19 days[ Soil respiration in microcosms amended with glucose and pesticide was of the same order as in systems with glucose only^however\ soil res! piration was signi_cantly impeded in microcosm systems with a low pesticide content and stimulated in systems with a high pesticide content[ 3[ Bacterivorous protozoa "naked amoebae and heterotrophic~agellates# were a}ec! ted at all tested concentrations "9=63Ð649 mg L Ð0 # of fenpropimorph[ High con! centrations\ 5=5Ð649 mg L Ð0

Molecular comparison of cultivable protozoa from a pristine and a polycyclic aromatic hydrocarbon polluted site

“…The contamination with PAH probably affects protozoan diversity directly via its toxicity and indirectly via its effect on the bacterial prey (Ekelund, 1999). Toxic effects of PAH in the soil we studied have already been observed on the soil microfauna (Gillet and Ponge, 2005), and, generally toxicity of PAH compounds to soil organisms, other than protozoa, is well documented (Edwards and Fletcher, 1971;Dorn et al, 1998;Crouau et al, 1999).…”

Application of the denaturing gradient gel electrophoresis (DGGE) technique as an efficient diagnostic tool for ciliate communities in soil

“…Several reports have shown that ciliates are susceptible to a wide range of environmental stressors such as insecticides (Petz and Foissner, 1989), biocides (Ekelund, 1999;Foissner, 1997), heavy metals or polychlorinated biphenyls (Foissner, 1994), and are thus a potential target group for screening the ecotoxicological effects of pollutants (Sauvant et al, 1999).…”

Test of Direct and Indirect Effects of Agrochemicals on the Survival of Fecal Indicator Bacteria

“…This effect has been seen in multicellular organisms (39-41, 43, 45) and microorganisms (15)(16)(17). Alternatively, agrochemicals may cause density-mediated, rather than trait-mediated, indirect effects via direct toxicity to a target species' food resources, parasites, competitors, or predators (18,21,22,36,41,(44)(45)(46)51). FIBs, pathogens, and other organisms ranging from bacterivorous protozoa to algae to aquatic animals are exposed to agrochemicals in environmental waters that receive agricultural runoff, but we know very little about the effect of the chemicals on the fate of microorganisms in such systems.…”