Eriophyid mites, spider mites and predatory mites on red raspberry in south-eastern Norway

Abstract: Plant-feeding mites can cause direct physical damage and act as virus vectors,
making them an economically important pest group in raspberry. The European Union (EU)
Green Deal policy to reduce chemical pesticides by 50 % by 2030 may lead to a lack of
acaricides in minor crops like raspberry. Therefore, understanding the mite dynamics in this
crop is of increasing importance. This study aimed to investigate the species composition of
plant-feeding mites and predatory mites on raspberry leaves and the association between the
plant-feeding mites and raspberry leaf blotch virus (RLBV). Five biweekly samplings were
carried out in a total of four sites from June to early August 2022 in Norway. Phyllocoptes
gracilis (Nalepa) (Acari: Eriophyidae) was the only eriophyid mites found at all sites. At least
one species of spider mites, Tetranychus urticae Koch (Acari: Tetranychidae), and two species of predatory mites, Anystis baccarum (Linnaeus) (Acari: Anystidae) and Typhlodromus (Typhlodromus) pyri Scheuten (Acari:Phytoseiidae), were found at all sites, indicating a potential for conservation biological control. Raspberry leaf blotch virus (Emaravirus idaeobati) was detected in both eriophyid and spider mites. This implies that besides P. gracilis, spider mites are also potential vectors of RLBV. Transmission experiments of RLBV by spider mites are recommended to confirm this.