Predatory Fauna

*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

A wide range of predators have been exploited, or have the potential to be exploited, as biological control agents against pests of fruit. In the British Isles, these include members of the families Miridae (mirid bugs) (Hemiptera), Anthocoridae (flower bugs) (Hemiptera), Forficulidae (earwigs) (Dermaptera) and several mite families.

Predatory mirids are found on a range of fruit trees, but particularly on apple. The commonest include Blepharidopterus angulatus, Psallus ambiguus and Phytocorisspp. They feed on many phytophagous arthropods, but their greatest potential value is as predators of Panonychus ulmi (fruit tree red spider mite).

On apple trees, Anthocoris nemorum and Anthocoris nemoralis feed on aphids early in the year and later on P. ulmi and psyllids. The predator/prey relationship between A. nemoralis and Cacopsylla pyricola (pear sucker) constitutes an effective bio-control mechanism, and is the basis of integrated pest management (IPM) in pear orchards in southeast England.

The importance of Forficula auricularia (common earwig) as predators of pests, in particular aphids, may be underestimated, because their activity is nocturnal. Forficula auricularia is considered an important predator of Cydia pomonella (codling moth).

The value of mite predators in reducing populations of P. ulmi has been emphasised by many workers in various parts of the world. In particular, the phytoseiid mite, Typhlodromus pyrior, as commonly known to growers, 'Typhs', has been shown to be able to regulate P. ulmi at low non-damaging levels if a spray programme is adopted that allows the predator to thrive. Predatory mites that feed on P. ulmi and Aculus schlechtendali (apple rust mite) include species from four families - Phytoseiidae, Stigmaeidae, Erythraeidae and Anystidae. At least ten species of predatory phytoseiid mites are known to occur on unsprayed apple trees both on foliage and bark. However, most of these species are susceptible to a wide range of agrochemicals and T. pyri is virtually the only one that can survive in managed apple orchards.

The only previous study of mite fauna in local Bramley orchards was by MacQuillan (1966). He presented both pest and beneficial species found in a neglected orchard near Richill, Co. Armagh and listed T. pyri as scarce but Typhlodromus rhenanus and Phytoseius macropilisas common. However, a more recent survey of predatory fauna within commercial orchards undertaken by the current author (Cuthbertson, AGS, unpublished data) indicated that the most commonly occurring predator in the orchards was the generalist predatory mite, Anystis baccarum (the 'whirli-gig' mite). Cuthbertson et al. (2003a,b) went on to show how A. baccarum can impact on A. schlechtendali and Rhopalosiphum insertum (apple-grass aphid) populations within the Bramley orchards. Anystis baccarum also proved compatible with various fungicides commonly used for apple scab control (Cuthbertson and Murchie, 2003a) and therefore offers much potential to be integrated into pest control programmes for the bio-control of economically important pests of apple (Mowat and Clawson, 1996; Cuthbertson and Murchie, 2000).

Apple growers should be encouraged to recognise and conserve A. baccarum populations, and indeed all predatory fauna, within their orchards (Cuthbertson and Murchie, 2003b).

References / further reading

Cuthbertson, A.G.S. and Murchie, A.K. (2000). The prospect of biological control within Northern Ireland Bramley orchards. Biology and Environment: Proceedings of the Royal Irish Academy 100B:50.

Cuthbertson, A.G.S. and Murchie, A.K. (2003a). 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. (2003b). The need for proper identification of beneficial and pest species in the Bramley apple orchards. 3pp.       http://www.ruralni.gov.uk/crops/fruit/top_fruit/technical_information/proper_identification.htm

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.

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

Mowat, D. J. and Clawson, S. (1996). The need for pest control in Northern Ireland Bramley apple orchards. Crop Protection in Northern Britain 2:225-230.