THE PREDATORY MITE EUSEIUS GALLICUSAND POLLEN FOOD SUPPLEMENTS: AN EFFECTIVE LINE OF DEFENSE IN DUTCH PROTECTED ROSES

摘要

The predatory mite species Euseius gollicus Kreiter-Tixier (Acari: Phytoseiidae) has been collected on protected roses cv. Red Naomi in the Netherlands, in 2011. It is commercially available since January 2014. The cage and field experiments conductedin the Netherlands and Belgium showed that it is a promising candidate for augmentative biological control of western flower thrips Frankliniella occidentalis (Per-gande) (Thysanoptera: Thripidae). In a cage experiment with rose plants, E. gallicus reproduced faster than Euseius ovalis and maintained the longest a low level of thrips damage. As the species can build up substantial populations on pollen supplements, even in absence of prey, preventative establishment can be accomplished with applications of Typha angustifolia L. pollen (Nutrimite). The pollen is blown at the rate of 500 grams per hectare every two weeks. Using this strategy, E. gallicus reached, in absence of prey, densities of 0.3 to a maximum of 2 mites per leaf, which is substantially higher than the densities realized with Amblyseius swirskii Athias-Henriot at 0.03 to a maximum of 0.3 per leaf (Pijnakker et al., 2014). The strategy allows growers to build a stronger standing army, while saving on labour and costs associated with repeated releases. In protected roses predatory mites, no longer need to be sprinkled weekly or released monthly by labour intensive placing of slow release sachets. It is sufficient to introduce predators once or twice per year. The application of pollen, by comparison, requires a mere thirty minutes per hectare every two weeks. Commercial releases of F. gallicus are only recommended in integrated crops that refrain from using sulphur and broad spectrum pesticides. Merely in July and August, additionalcontrol measures against thrips may be required.