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1 January 2010 Stability of Natural Populations of an Aphid, Uroleucon rudbeckiae, at Three Spatial Scales
Robert J. Lamb, Patricia A. MacKay
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Stability (temporal variability, persistence, resilience) was assessed over 8–13 years for subpopulations, populations, and regional populations of Uroleucon rudbeckiae (Fitch) (Hemiptera: Aphididae) in southern Manitoba, Canada. Contrary to expectations, natural populations of this native aphid were not more stable than those of aphids inhabiting crops. Among population parameters, prevalence (proportion of plants infested) proved more effective for quantifying temporal variability than intensity (colony size) or abundance (number of aphids per stem). The parameter “population variability” was a more effective index of temporal variability than the standard deviation of the logarithm or the coefficient of variation. Small differences in temporal variability were detected among populations that varied greatly in size. Population variability declined slightly as spatial scale increased and did not increase consistently over time. Population variability can be considered characteristic of this species in southern Manitoba, having a value of 0.648 ± 0.080 (mean ± standard deviation, n = 5, over 8–13 years) on a scale of 0–1, a high degree of temporal variability. Persistence was not related to temporal variability. Subpopulations were less persistent than populations, and one of five populations did not persist. Small populations were more likely to disappear temporarily. No resilience was detected.

© 2010 Entomological Society of Canada
Robert J. Lamb and Patricia A. MacKay "Stability of Natural Populations of an Aphid, Uroleucon rudbeckiae, at Three Spatial Scales," The Canadian Entomologist 142(1), 36-51, (1 January 2010).
Received: 17 June 2009; Accepted: 1 September 2009; Published: 1 January 2010

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