Bionomics of Phytoseius fotheringhamiae Denmark and Schicha, 1974, (Acarina: Phytoseiidae) on apple in Australia

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Abstract
P. fotheringhamiae was the dominant phytoseiid mite species on leaves of neglected apple trees at Bathurst. It preyed mainly upon eriophyid mites, young and quiescent stages of tydeid mites, and young stages of Bryobia sp. Its two reproductive phases in summer and early autumn were linked closely to the two activity phases of the eriophyid mites.The large number of P. fotheringhamiae mites on the leaves throughout the years had hardly any impact on the Bryobia sp. population but a loose predator‐prey relationship might exist between tydeid mites and the predator. T. urticae was only found in very low numbers on neglected trees. It is concluded that the ever present P. fotheringhamiae, distributed almost equally over the trees, prevented a development of invading T. urticae. Other T. urticae predators such as Stethorus spp. were extremely rare. Experiments in micro‐culture cells demonstrated that P. fotheringhamiae can live for long periods and reproduce with T. urticae as their only food. A single egg‐laying female can consume an average of 5.41 deutonymphs of T. urticae per day. P. fotheringhamiae might have difficulty in controlling large populations of T. urticae once these have established their webbings over the leaves.Zusammenfassung: Zur Lebensweise der Raubmilbe Phytoseius fotheringhamiae Denmark und Schicha auf Apfelbäumen in AustralienUnter mehreren neu beschriebenen Arten räuberischer Obstbaummilben (Acarina: Phytoseiidae) in Bathurst, im Staat von New South Wales, Australien, wurden Phytoseius fotheringhamiae Denmark und Schicha besonders häufig auf vernachlässigten Apfelbäumen gefunden. Dort verhinderte die Art eine Invasion der Spinnmilbe Tetranychus urticae (Koch), der schlimmsten Milbenplage im Bathurst Obstbau‐Distrikt. Daten über Biologie und Ökologie von P. fotheringhamiae während der Jahre 1971 bis 1974 zeigen, daß die Milbe ein wirksamer Räuber ist; ein einzelnes eierlegendes Weibchen kann 5.41 Deutonymphen von T. urticae pro Tag vertilgen.