European red spider mite - an environmental consequence of persistent chemical pesticide application

The European red spider mite, Panonychus ulmi, is a major pest in almost all fruit growing regions of the world (Hardman et al., 1985). Spread of P. ulmi to most apple-growing areas has probably been caused by the distribution of nursery stock carrying winter eggs. This mite is stated to be an important secondary pest (due to the effects of chemical sprays killing natural enemies) of commercial orchards throughout the United Kingdom (UK) and Europe (Cross and Berrie, 1994). A wide host range includes deciduous bushes and trees belonging to the family Rosaceae, but it is in association with fruit trees such as apple, pear, plum, peach, prune and cherry that it reaches economic importance. In commercial orchards, the potential of P. ulmi to cause severe economic damage necessitates chemical control several times a year (Croft, 1975).