Biological control of the red spider-mite in tomatoes under arid and semi-arid conditions in Israel

Abstract: The red spider mite, Tetranychus urticae, is one of the most devastating polyphagous pests world-wide. In protected tomato cultivations in Israel it is the most difficult pest to control due to its rapid development of resistance to acaricides. Climatic conditions of the main cultivation area are favourable for mite development year round. The common practice of tomato growers is to spray every 7-10 days using different chemicals to control spider mites, yet in many plots significant damage and loss of yield is recorded. Here we report on implementation of biologically-based IPM program which involves weekly scouting and releases of the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) that resulted in 70% decrease in acaricides use and improved control of the pest. During two consecutive seasons we compared the efficacy of spider mite control between IPM-biocontrol treated plots and chemically treated plots. The chemically-treated plots used 4 times more acaricides than the IPM-treated-plots. Nonetheless, the spider mite load (calculated as the number of spider mites per area X number of days that spider mites were present in that area) was three times higher in the chemically-treated plots. These results, coupled with commercial and technical field experience of the last three years, confirm that implementing Phytoseiulus persimilis in tomato crop and taking decisions based on sophisticated scouting, yield a safer and more potent system to control spider mites.