The synthetic pyrethroids, alphacypermethfin and bifenthrin, were evaluated in the laboratory and field for their impact on the survival of five acarine predators of the pasture pest, Halotydeus destructor (Tucker). In laboratory bioassays, alphacypermethrin at the proposed field rate (5 g a.i. ha -1) for H. destructor and the scarab beetle pest, Aphodius tasmaniae Hope caused medium-high mortality to Walzia australica Womersley (Anystidae), Bdellodes aj~nis Atyeo (Bdellidae), Balaustium murorum (Hermann) (Erythraeidae) and Parasitus fimetorum (Berlese) (Parasitidae) but was not toxic to Cyta latirostris (Hermann) (Bdellidae). In the field, populations of VE. australica and B. a.fflnis treated with this rate were significantly reduced but recovered after 8 weeks. Bifenthrin at 5 g a.i. ha -l killed 96-100% of g(. australica, B. aj~nis, B. murorum and P. fimetorum in laboratory bioassays and significantly reduced field populations of W. australica and B. a fflnis for 17 weeks. In bioassays both products at 2.5 g a.i. ha-1 permitted 10-30% survival of B. affinis and B. murorum and alphacypermethrin permitted 59% survival of g(. australica. A 2.5 g a.i. ha-~ rate of alphacypermethrin is recommended for control of H. destructor in pasture when A. tasmaniae is not present, thus minimizing the impact of chemical control on the survival of some predatory mite species.

Mite populations on grapevines in five Canberra district vineyards during 1991-1993 were characterised by large numbers of phytoseiids and small, non-damaging populations of the pests grapeleaf blister mite, Colotnerus vifis (Pagenstecher), and grapeleaf rust mite, Culepifritnerus vitis (Nalepa). Six phytoseiid species (Typhlodromus doreenue Schicha, T. dossei Schicha, T. uustrulicus (Womersley), Amblyserus walterri Schicha, A . elinae Schicha and Phytoseius forheringhamiue Denmark and Schicha) were recorded. T. doreenae was the dominant species and occurred in all vineyards. P. folheringharniue was abundant in a single vineyard and T. dossei occurred in small numbers in two vineyards. The other species were represented by single individuals.Implications of these results for viticultural mite management based on biological control are discussed.