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Temporal and Spatial Dynamics of an Acarine Predator-Prey System

Gosta Nachman
Journal of Animal Ecology
Vol. 50, No. 2 (Jun., 1981), pp. 435-451
DOI: 10.2307/4065
Stable URL: http://www.jstor.org/stable/4065
Page Count: 17
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Temporal and Spatial Dynamics of an Acarine Predator-Prey System
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Abstract

(1) Temporal variations in the average population densities of the phytoseiid predator Phytoseiulus persimilis and its prey, the two-spotted spider mite (Tetranychus urticae), were followed during 23 weeks in three commercial glasshouses. Both species showed clear oscillations attributable to predator and prey interactions. (2) Analyses of variance show that the populations become more unevenly distributed, both vertically and horizontally, within the glasshouses as the population densities increase. (3) The variance/mean relationship of both species is shown to obey Taylor's power law. (4) The negative binomial and the Polya-Aeppli distributions have been fitted to the empirical distributions. The negative binomial gives, in general, the best agreement. (5) The parameter k of the negative binomial distribution is shown to be density dependent. Maximum likelihood estimates of k are compared with model predicted values but the quantitative agreement is rather poor. They agree, however, reasonably well, qualitatively. (6) Spatial coincidence between the two species is expressed by the correlation coefficient. The predator population seems to be better distributed relative to the prey as the density of either population increases.

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