Thrips control with predatory mites A. limonicus and A. swirskii in different strawberry cultivation systems

Western flower thrips or Frankliniella occidentalis is the most common thrips present on strawberry plants and causes damage to strawberries worldwide. F. occidentalis feeds on the cell content of developing flowers and fruits which results in aberrant fruit characteristics: grooves, cat faces, bronzing and prominent seeds. To combat thrips, a wide range of chemical products are used. However, upcoming resistance of thrips to these chemicals causes loss of efficiency. Hence, a new solution to control thrips in strawberries is becoming a high priority. Both the risk for resistance when using chemicals and the urge to lower residues on fruit, increase the interest in natural enemies to control pests. At Research Centre Hoogstraten (PCH), we screened multiple predators for their suitability to control thrips in strawberry. Unique for strawberry cultivation in Belgium and The Netherlands is that it takes place in multiple systems year-round of which the season is relatively short and therefore it is important that predators can survive and establish a sufficient population in these different conditions. At PCH we screened compatible predators for their efficiency to control thrips in the different cultivation systems. This intense search payed off and two predatory mites proved their ability to combat thrips in both individual cages and multiple cultivation systems at PCH and private cultivators. Amblydromalus limonicus is able to control thrips in mild conditions, Amblyseius swirskii prefers warmer temperatures. The predatory mite is scattered over the crop and it will establish itself on the leaves whenever food is available. When thrips levels rise, the predatory mites increase in population and are able to keep thrips at non-damaging levels. A. limonicus and A. swirskii are therefore perfectly suitable to become an important aspect of integrated pest management (IPM) in strawberry so that high quality fruit can be maintained.