Euseius gallicus, a bodyguard for roses
Abstract: In 2014 more than 70% of the Dutch rose growers practice Integrated Pest Management. The successes booked with Phytoseiulus persimilis against spider mites [Tetranychus urticae (Koch)] have greatly contributed to this development. However, the presence of Western Flower Thrips [Frankliniella occidentalis (Pergande)] remains a bottleneck. Due to the low pest density in roses, the inundative releases of predatory mites don’t result in good colonization and thus fail to provide effective preventative control. Cosmetic damage to flower buds and petals caused by the pest are the result. A strain of the phytoseiid mite Euseius gallicus Kreiter & Tixier was collected in January 2013 in a commercial rose crop and has shown to be a promising control agent. In a cage experiment, E. gallicus could survive on rose plants and reduce thrips density and damage. A series of trials in greenhouse grown roses demonstrated that the predator in combination with pollen (Nutrimite) establishes better under field conditions than the commonly used predator Amblyseius swirskii (Athias Henriot). High densities of Euseius gallicus were obtained within six weeks in absence of prey and populations persisted as long as pollen was applied. Repeated inundative introductions of predators were no longer required. The use of E. gallicus with pollen is the first commercial strategy in ornamentals offering year-round protection against pests.