Phytophagous mites and their predators in New Zealand orchards

Abstract

Panonychus ulmi (Koch), the most important phytophagous mite on apple, plum, and peach trees, had five and sometimes six generations in a year; summer eggs were laid from mid-October until mid-April, and winter eggs from mid-January until late May. Bryobia rubrioculus Scheut., on apple and plum trees, had three generations and a partial fourth, Tetranychus urticae Koch occurred on a wide range of host plants and was more abundant on fruit trees in the drier districts, while Tetranychus lambi P. & B. was found only in the Auckland area. Panonychus citri (MeG.), Eotetranychus sexmaculatus (Riley), Petrobia harti (Ewing), and Petrobia latens (Muller) also occurred.

Stethorus bifidus Kapur (Coccinellidae), the only important predacious insect, had two generations in summer on deciduous trees, and was also active on citrus and other evergreens during the winter; it fed entirely on mites of several species and the larval development and number of eggs laid by females is related to supply of P. ulmi as food. Idatiella albisignata Knight (Miridae ), a general predator of various insects and mites, occurred rarely. Typhlodromus pyri Scheut. (Acarina: Phytoseiidae) was abundant in deciduous orchards, and had at least five generations, during the summer. Amblyseius cucumeris (Oudms.) and A. largoensis (Muma) occurred less abundantly on deciduous trees, the latter also on citrus. Agistemus longisetus Gonzalez (Acarina: Stigmaeidae) was abundant in deciduous orchards in late summer, and fed on P. ulmi and B. rubrioculus in preference to Tetranychus spp.; it increased at a faster rate, and frequently reached greater numbers, than the phytoseiid spp.