Predacious Mites for Control of Citrus Thrips,Scirtothrips citri(Thysanoptera: Thripidae) in Nursery Citrus

Abstract

Abstract Predation on citrus thrips,Scirtothrips citri(Moulton), by four species of predacious mites,Ipheseius degeneransBerlese,Euseius tularensisCongdon,Neosieulus cucumeris(Oudemans), andN. barkeri(Hughes) was studied. In the laboratory,I. degeneransandE. tularensisexhibited a consistently high consumption rate of second-instar citrus thrips (4–5 thrips per mite per day), 68–96% survival, and reproduction of 0.9–2.5 eggs per day during the 5-day experiment. Initially,N. cucumerisexhibited a lower consumption rate as well as lower survival and egg production compared withI. degeneransandE. tularensis;however, these rates increased as the experiment progressed. The fourth species,N. barkeri,responded poorly with respect to all three biological parameters. In experiments using potted citrus in a greenhouse, immature stages of citrus thrips were not always available for predation. Under these circumstances,I. degeneransandE. tularensissurvived well and reduced immature citrus thrips to undetectable levels for the 4-week period after release. In contrast,N. cucumerisandN. barkeriexhibited poor survival and did not fully control citrus thrips. WhenI. degeneransandE. tularensiswere released onto potted citrus trees in a commercial citrus nursery, releases ofI. degeneransreduced citrus thrips for two sampling periods and improved tree height and leaf number comparable with an abamectin insecticide treatment. In contrast,E. tularensisreleases did not control citrus thrips, resulting in less growth of trees. These data suggest thatI. degeneransshows promise for commercial releases and control of citrus thrips in citrus nurseries.