Survey and seasonal abundance of thrips species occurring in flowering plants surrounding greenhouses in the Netherlands

Abstract: In the Netherlands, areas surrounding glasshouses are normally uniform and simple in habitat structure, usually comprising of short grass grazed by animals or frequently mowed, fences and canals separating properties. This homogeneous habitat provides little support for spontaneously occurring natural enemies that could enter greenhouses to provide biological control services, while it is also aesthetically poor for the region of South Holland which is densely populated. However, increasing biodiversity adjacent to greenhouses could also increase pest densities, particularly those of pestiferous thrips species. Here we present the results of a study where biodiversity plots were created in 4 sites near commercial greenhouse cultivations. During the 2022 season, we followed the abundance and species composition of thrips and their anthocorid predators in flowers of different plant species. Abundance of thrips was higher in plots with flower strips compared to control plots, reaching their peak in July. Preliminary results show that Frankliniella intonsa, Thrips tabaci and Thrips fuscipennis are the most common species found in early summer. The key pest Western flower thrips Frankliniella occidentalis represented only 6 % of the adult specimens identified in June and July 2022. Results of this study will improve our knowledge on thrips fauna found on specific plants and may eventually lead us to the selection of plant species that do not increase pest pressure for greenhouse horticulture.