Untersuchungen zur Migration der Raubmilbe Phytoseiulus persimilis Athias-Henriot (Acarina: Phytoseiidae). 1 Abhaengigkeit der Migration von Phytoseiulus persimilis Athias-Henriot (Acarina: Phytoseiidae) vom Entwicklungsstadium, dem Alter der Weibchen sowie der Entfernung der Kolonien von Tetranychus urticae Koch (Acarina: Tetranychidae).
1994
Koehler G.
Youth stages of Phytoseiulus persimilis hardly reach colonies of Tetranychus urticae. P. persimilis seems to stay in its original colony up to its copulation. At the beginning of the oviposition period the motivation of P. persimilis-females to emigrate from T. urticae-colonies with a lack of food is briefly higher than in its further development. The success of search during that time is much higher too. The suppression of the rate of emigration by an increasing number of P. persimilis females (Bernstein, 1985) was found from the 4th day of the oviposition period, whereas very young females (1st day of the oviposition period) do not show that reaction. Intraspecifical interference during migration to other colonies is also decreased in the case of younger P. persimilis-females in comparison with older females. Bernstein (1985) described descending rates of emigration with increasing density of P. persimilis. In the experiment described here the density per square unit was not changed. Nevertheless, a higher number of P. persimilis led to a lower rate of emigration. A high number of emigrants results in a lower immigration in T. urticae-colonies caused by intraspecifical interference. A growing distance to the next T. urticae-colonies give rise to a decreasing rate of immigration and growing intraspecificial interference.
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