The polyphagous mite Euseius gallicus (Kreiter & Tixier): A new predator able to persist in glasshouse roses

Abstract: Since the 2000’s, Dutch and Belgian rose growers are introducing predatory mites in their greenhouses. Phytoseiulus persimilis is controlling with success spider mite Tetranychus urticae. Neoseiulus cucumeris and Amblyseius swirskii are mainly introduced against Western Flower Thrips. But most of these integrated growers still face a zero pest tolerance. With the absence of thrips at the beginning of the crop season, long-term persistence of predators is not possible. Until now, growers had to repeat introductions of Phytoseiids for lack of better alternatives. With this strategy thrips damage remains an issue. Growers are asking for predators which persist in their crop. Predatory mites of Type IV like Euseius spp. that feed on pollen and (non-damaging) on plants (Adar et al., 2012) can fulfil this role. These traits make them ideal candidates for biological control in long growing greenhouse crops. Euseius gallicus is occurring naturally throughout Europe (e.g. in France, Germany, Belgium, The Netherlands, Turkey and Tunisia (Döker et al., 2014)). The species is found on a variety of outdoor host plants, including: Rosa spp., Tilia platyphyllos, Olea europea, Prunus cerasus, Aesculus hippocatanum, Ipomea sp., Viburnum tinus, Vitis vinifera, Lycium barbarum, and Tilia cordata. The mite was also found in 2013 on glasshouse roses in The Netherlands during a survey. Biobest developed and patented a method for the mass production of Euseius gallicus in 2013. The predator has since 2014 been successfully used in greenhouse rose crops. The predatory mite is used with biweekly applications of a low dosage of NutrimiteTM pollen (500 g/ha). This low amount of pollen does not stop the phytoseiid from attacking the pests. With a pollen applicator, growers can treat one hectare in 30 minutes. E. gallicus responds stronger to pollen as food source than the other commercially available phytoseiid species. E. gallicus has also potential in sweet pepper, cucumber, Skimmia, Poinsettia, Hedera, Hibiscus, Anthurium, Calathea and strawberries. A possible drawback of E. gallicus lies in the fact that, as most plant feeding predators, the species is more susceptible to systemic pesticides like neonicotinoids (Put et al., 2015) and to sulphur. Its efficacy in vegetable crops can be jeopardized by the use of neonicotinoids against phytophagous bugs.Extended abstract