Prey mites as an in-crop food: an innovative strategy to enhance biocontrol on chrysanthemums

Abstract: The preventive establishment of predatory mites in cut flower crops where pollen is not available is one of the main problems unresolved. In order to favor the establishment of predatory mites an innovative strategy based on releases of astigmatid mites at the top of the plants as an in-crop food source has been developed by Agrobio after 3 years of trials. In this work, results of one year trials on chrysanthemums performed on three commercial Dutch greenhouses are presented. A program was set up based on 4 releases of Transeius montdorensis together with 6 releases of prey mites. Specific machinery was designed for spreading both predators and prey mites. A mean number between 23 and 31 predatory mites per plant were counted on week 6, regardless of the season of the year. Populations of thrips were successfully controlled and remained low with no more than 0.2 individuals per plant. Three further strategies all based on early releases already in the nursery were evaluated. An earlier establishment was accomplished in all cases and the best results were achieved when additional releases of predators and preys were performed on week 1.