Movement of Phytoseiulus persimilis (Acari: Phytoseiidae) on the leaves of greenhouse carnations and other cut flowers

Abstract

The behaviour and mobility of the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) was observed on vertically orientated leaves of carnations (Dianthus caryophillus) and compared to five other greenhouse plants: Cymbidium orchids (Cymbidium spp.), roses (Rosa spp.), French beans (Phaseolus vulgaris), gypsophila (Gypsophila paniculata), and thalictrum (Thalictrum delavayi). P. persimilis had difficulty maintaining traction on carnation leaves, with only two out of 15 able to complete a vertical 25 mm test run. It was able to adhere to the remaining five plant species but the mean time to complete the prescribed distance ranged from 12.8 s on cymbidium orchid to 65.0 s on thalictrum. Scanning electron micrographs showed the waxy layer of the leaf cuticle of these plants varied from highly ornamented, dense layers of wax filaments on carnations to smooth surfaces on beans. It is suggested that the failure of P. persimilis to control two-spotted mite (Tetranychus urticae Koch) (Acari: Tetranychidae) on carnations is a result of its inability to maintain traction on the waxy surface of the leaves and stems.