Evaluation of Selected Groundcovers As Banker Plants for Predatory Mites

A research project was conducted, in partnership with UF Extension Specialists, to evaluate landscape groundcovers as banker plants to support predatory mites in the absence of prey.  We used Amblyseius swirskii (McGregor) in our tests because it an effective predator of Chilli thrips, Scirtothrips dorsalis (Hood), a significant pest of knockout roses and other landscape ornamentals.  We hypothesized that in the absence of arthropod prey, A. swirskii might be sustained on a diet of pollen or other plant nutrient sources such as extrafloral nectaries.  Groundcovers expected to provide favorable conditions and with potential to be used as a companion plant to landscape roses were evaluated: 1) sterile lantana, Lantana camara; 2) sensitive plant, Mimosa strigillosa; 3) alyssum ‘Snow Princess’™, Lobularia hybrid; 4) beach sunflower, Helianthus debilis; 5) ‘Hip Hop’ Euphorbia, Euphorbia hypericifolia ‘Hip Hop’™; 6) stoloniferous perennial peanut, Arachis pintoi; 7) blue daze, Evolvulus glomeratus; 8) verbena, Verbena sp.; 9)  wild petunia Ruellia caroliniensis; and 10) black foot daisy Zinnia paladosa.   Five replications were studied in two four week trials.  Plants were enclosed within screen cages, infested with 30 predatory mites, and maintained in a greenhouse.  The tallest three meristems were inspected with a hand lens weekly in the first trial and biweekly in the second.  Numbers of predators and other pertinent observations were recorded.  The study was conducted twice; at the end of the trial remaining predators were collected using Berlese funnels.  Results showed significant differences between treatments (p=0.05) with significantly more mites collected from ‘Snow Princess’™ alyssum than other treatments.  This plant will be infested and installed in a rose garden for field evaluation.