Biological Control of Pests
at the Royal Botanic Garden, Edinburgh, Scotland

by Pat Clifford, Senior Horticulturist
Click images to enlarge

At the beginning of the 2006 season our Nelumbos nearly succumbed to a nasty infestation of the red spider mite (Tetranychus urticae). A solution had to be found fast. At RBGE the policy is to use biological control whenever possible. This is particularly important when dealing with ponds, which may or may not contain fish. In this case we opted for the Fast-Action Mite Predator (Phytoseuilus persimilis).  

 
Above and left, red spider mite infestation.
Below, after treatment.

 They arrive in a small bottle which contains 400 adults packed in vermiculite which are released onto the affected plants. The tiny 0.5mm (0.02") females then begin feeding and laying eggs, up to 60 at a time, in the spider mite concentrations.
These voracious predators have to hunt and eat constantly to survive. Their huge appetites in fact contribute to their own demise - when they've eaten all the spider mites they starve. If another infestation occurs more need to be added. The predators need to be in conditions with a minimum temperature of 16°C (60°F) and high relative humidity of 60-90%, which is ideal for our tropical glasshouses. They are unbelievably fast acting and effective.

 

 

 

 

 See Pat's biological control of aphids that afflict Victoria here

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