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Aggregation in the Birch Aphid Euceraphis punctipennis (Zett.) in Relation to Food Quality
S. D. Wratten
Journal of Animal Ecology
Vol. 43, No. 1 (Feb., 1974), pp. 191-198
Published by: British Ecological Society
Stable URL: http://www.jstor.org/stable/3166
Page Count: 8
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(1) Populations of the birch aphid were highest in spring and autumn; in mid-summer the reproductive rate was low and the population consisted mainly of adults. (2) The leaves of birch were not completely in phase with one another during either the maturation or senescence periods. This led to the occurrence of larger numbers of birch aphids at these times on those leaves whose nutritional status was higher than average. (3) The changes in the suitability of the leaves of birch as feeding sites were reflected by the changing index of aggregation of the aphid through the season. The aphids' distribution was random for a maximum of only 3 weeks in mid-summer, when all leaves were mature. At other times some leaves were more favourable than others and the aphids exploited these differences through their mobility and aggregation behaviour.
Journal of Animal Ecology © 1974 British Ecological Society