Presence of anystis baccarum

*Present address: Dr Andrew G. S. Cuthbertson, Central Science Laboratory, Sand Hutton, York YO41 1LZ, U.K. Tel.: +44 (0) 1904 462201; Fax: +44 (0) 1904 462111; E-mail: a.cuthbertson@csl.gov.uk

The Bramley's Seedling apple orchards in Northern Ireland are concentrated in the drumlins of Co Armagh and are a locally-important crop representing 98 per cent of top fruit production. The farm gate value of the crop is around £6 million per annum.

Orchards are long-term and stable agro-ecosystems that have well documented fauna, many of which are pest species. During the 1950s to 1970s overuse of broad-spectrum chemical insecticides led to some formerly minor pests (e.g. fruit tree red spider mite Panonychus ulmi) becoming economically damaging because the insecticides killed their natural enemies and their populations increased unhindered. For this reason, and also due to the stability of the ecosystem, much emphasis has been placed on biological control of orchard pests, particularly the mite P. ulmi and the apple rust mite Aculus schlechtendali.

In English orchards, the main predators of pest mites are the phytoseiid and stigmaeid mites, Typhlodromus pyri and Zetzellia mali, respectively. However, in trapping and leaf washing studies by the current author (Cuthbertson, AGS) the most common predatory mite sampled in Co Armagh Bramley orchards was the prostigmatid 'whirli-gig' mite, Anystis baccarum(Cuthbertson and Murchie, 2005a), a relatively large (body diameter 1.0-1.5mm), orangy-red and fast moving species.

Anystis baccarum is cosmopolitan and feeds on many pests on a wide variety of crops. These include: phytophagous mites on blackcurrant bushes in Russia, aphids on cereals in England, tortricid larvae on apple trees in New Zealand and red spider mite on peach trees in Canada. Mites of the genus Anystishave been reported before to occur within unsprayed orchards in Northern Ireland (MacQuillan, 1966) but until now no individual species was ever identified (Cuthbertson and Murchie, 2004; Cuthbertson, 2005). Along with A. baccarum, at least three other species of the genus, A. salicinus, A. cornigerum and A. cursorium occur in the British Isles (Dr A. Baker, British Natural History Museum, London, pers. comm.). The prevalence of A. baccarum in Northern Ireland highlights regional differences in the fauna of UK apple orchards.

Anystis baccarum does contribute to biological control of pests in Co Armagh Bramley orchards. It has been shown experimentally to play a significant role in limiting the population development of A. schlechtendaliand to be a predator of apple-grass aphid Rhopalosiphum insertum (Cuthbertsonet al., 2003a,b). Furthermore, it appears relatively compatible with fungicides routinely used in the orchards to control apple scab (Cuthbertson and Murchie, 2003). Apple scab is by far the most serious disease problem facing Northern Irish apple growers, with as many as 14 fungicide sprays applied within one season. Although more work is required to determine the biocontrol value ofA. baccarum, it is important that this predatory mite is recognised as a beneficial species by the apple growers and steps taken to conserve their populations (Cuthbertson, 2004; Cuthbertson and Murchie, 2005b).

Cuthbertson, A.G.S. (2004). Unnecessary pesticide applications in Northern Ireland apple orchards due to mis-identification of a beneficial mite species. Research Journal of Chemistry and Environment 8 (3): 77-78.

Cuthbertson, A.G.S. (2005). Re-discovery of a predatory mite in Northern Irish apple orchards. Biodiversity News 30 (1): 29.

Cuthbertson, A.G.S. and Murchie, A.K. (2003). The impact of fungicides to control apple scab (Venturia inaequalis) on the predatory mite Anystis baccarum and its prey Aculus schlechtendali (apple rust mite) in Northern Ireland Bramley orchards. Crop Protection 22: 1125-1130.

Cuthbertson, A.G.S. and Murchie, A.K. (2004). The presence of Anystis baccarum (L.) in Northern Ireland Bramley apple orchards. Irish Naturalists' Journal 27: 465-467.

Cuthbertson, A.G.S. and Murchie, A.K. (2005a). Techniques for environmental monitoring of predatory fauna on branches of Bramley apple trees in Northern Ireland. International Journal of Environmental Science and Technology. In press.

Cuthbertson, A.G.S. and Murchie, A.K. (2005b). Dyna-mite in Northern Irish orchards! The Fruit Grower. In press.

Cuthbertson, A.G.S., Bell, A.C. and Murchie, A.K. (2003a). The impact of the predatory mite Anystis baccarum on apple rust mite (Aculus schlechtendali) populations in Northern Ireland Bramley orchards. Annals of Applied Biology 142: 107-114.

Cuthbertson, A.G.S., Fleming, C.C. and Murchie, A.K. (2003b). Detection of Rhopalosiphum insertum (apple-grass aphid) predation by the predatory mite Anystis baccarum using molecular gut analysis. Agricultural and Forest Entomology 5: 219-225.

MacQuillian, M. J. (1966). The mite fauna of a neglected Northern Ireland apple orchard. Entomologist's Monthly Magazine 102: 153-155.