Exploring new methods for biological control of western flower thrips

Gepubliceerd op
3 februari 2015

Western flower thrips, Frankliniella occidentalis, is major pest in greenhouse ornamental plants. This report shows the results of experiments with top layers for predatory mites, banker plants for Orius and a Lure & Infect system for adult thrips.

Top layers consisting of a mixture of bark, bran and yeast increased densities of prey and predatory mites, both in the soil and on the plants. This resulted in a better control of thrips in alstroemeria and roses compared to treatments with predatory mites but without top layers. However, application at highinitial thrips densities could result in a temporary escape of thrips. Pepper plants, amaranthus and cornflowers were suitable banker plants for Orius. The best development of Orius was observed on cornflowers in a no-choice situation, but pepper plants were often preferred by Orius for oviposition when plants were mixed.

The Lure & infect system with Beauveria bassiana was not successful in controlling adult thrips. Only 10 % of the recaptured thrips were infected and no significant effects on thrips densities were observed. Moreover, laboratory experiments showed that infected females continue laying eggs for a few days, which makes this method less effective than killing adults directly after catching them.