Control of spider mite (Tetranychus urticae) on protected cherry using the predatory mite Amblyseius andersoni

Project summary:

This project will investigate the use of A. andersoni to prevent the build-up of Tetranychus urticae (two-spot spider mite, TSSM) in protected cherry orchards. Due to warmer, dryer conditions in protected cherry there has, in recent years, been a build-up in TSSM close to harvest. TSSM reduce the photosynthetic ability of the leaves and in severe cases cause webbing (Fig. 1) making harvest difficult or impractical. This was particularly problematic in 2013 when warmer dryer weather conditions promoted the population growth of TSSSM on cherry trees in tunnels and there is concern by agronomists that this may affect the subsequent years’ bud growth. The infestation builds up close to harvest when there are no reliable options of plant protection products. Clofentezine (Apollo 50) has a harvest interval of 56 days and only one application can be made in a season. Pyrethrums are damaging to natural enemies in the crop and of short persistence.

Hence, building up levels of predatory mites on cherry trees early in the season will help to keep spider mites in check.

We will test A. andersoni at two densities and two timings in orchards with a history of spider mite infestation in replicated randomised block designs. We will also test A. andersoni as a preventative or curative treatment on TSSM inoculated trees. This will enable us to provide recommendations for use of predatory mites by growers in protected cherry orchards.

East Malling Research and Syngenta Bioline have worked closely together on other predatory mite projects and the mites used in the studies will be supplied by the biocontrol company.

Aims and objectives:

Project aim: To test the efficacy of Amblyseius andersoni as a preventative and curative control agent of spider mites in protected cherry.