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Population growth rate and carrying capacity for springtails Folsomia candida exposed to ivermectin

Noel, H. L., Hopkin, S. P., Hutchinson, T. H., Williams, T. D. and Sibly, R. M. (2006) Population growth rate and carrying capacity for springtails Folsomia candida exposed to ivermectin. Ecological Applications, 16 (2). pp. 656-665. ISSN 1051-0761

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Abstract/Summary

Forecasting the effects of stressors on the dynamics of natural populations requires assessment of the joint effects of a stressor and population density on the population response. The effects can be depicted as a contour map in which the population response, here assessed by Population growth rate, varies with stress and density in the same way that the height of land above sea level varies with latitude and longitude. We present the first complete map of this type using as our model Folsomia candida exposed to five different concentrations of the widespread anthelmintic veterinary medicine ivermectin in replicated microcosm experiments lasting 49 days. The concentrations of ivermectin in yeast were 0.0, 6.8 28.83 66.4 and 210.0 mg/L wet weight. Increasing density and chemical concentration both significantly reduced the population growth rate of Folsomia candida, in part through effects on food consumption and fecundity. The interaction between density and ivermectin concentration was "less-than-additive," implying that at high density populations were able to compensate for the effects of the chemical. This result demonstrates that regulatory protocols carried out at low density (as in most past experiments) may seriously overestimate effects in the field, where densities are locally high and populations are resource limited (e.g., in feces of livestock treated with ivermectin).

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Biological Sciences
ID Code:10201
Uncontrolled Keywords:Collembola, density dependence, Folsomia candida, food availability, microarthropod, soil, soil invertebrate, springtail, ESTIMATING DENSITY-DEPENDENCE, TABLE RESPONSE EXPERIMENTS, LIFE-HISTORY, EISENIA-FOETIDA, ENCHYTRAEUS-ALBIDUS, DEMOGRAPHIC, RESPONSES, TOXICANT EXPOSURE, CADMIUM TOXICITY, TIME-SERIES, COLLEMBOLA

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