Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2002
Publication Date: 2/1/2003
Citation: Hansen, E. A., Funderburk, J., Ramachandran, S., Eger, J., Reitz, S.R., Mcauslane, H. 2003. Within-plant distribution of frankliniella species and orius insidiosus in field pepper. Environmental Entomology. 32(5):1035-1044. Interpretive Summary: Thrips feeding may result in distortion, discoloration, stunting and silvering of fruits of vegetable crops, and some species of thrips have been confirmed vectors of harmful plant viruses. Attempts to control thrips populations by regular applications of insecticides have led to resistance to most classes of insecticides. The bug Orius insidiosus is an effective predator of several pest thrip species attacking pepper and tomato. A scientist at the USDA-ARS Center for Biological Control, Florida A&M University, Tallahassee, collaborated with scientists from the University of Florida and Dow Agrosciences to study the within plant distribution of predator and prey and evaluate the effect of insecticides on the patterns of aggregation in pepper. In laboratory experiments, thrips showed a strong preference for pepper flowers over leaves and stems. In field studies, populations of thrips and the predatory bug O. insidiosus swere highly aggregated in the flowers in both untreated and insecticide- treated pepper. Also, population numbers in the flower of field pepper was sufficient for estimating the benefits of biological control in scouting programs based upon predator to prey ratio. These results will enhance control of thrips populations in pepper through fewer applications of insecticides and also lessen chances for further buildup of resistance to pesticides.
Technical Abstract: Recent research has revealed that Orius insidiosus (Say) is an effective predator of Frankliniella occidentalis (Pergande), F. tritici (Fitch), and F. bispinosa (Morgan) in the flowers of field pepper. The objectives of this research were to determine the within plant distribution of predator and prey and to evaluate the effects of insecticides on the patterns of aggregation. Field experiments were conducted in northern and central Florida during different times of the year to evaluate patterns of aggregation over a range of field conditions. In all experiments, populations of thrips and O. insidiosus in untreated and insecticide- treated pepper were highly aggregated in the flowers. In laboratory-choice experiments, the adults of F. occidentalis and F. tritici showed a strong preference for the pepper flowers over the leaves and buds. We conclude that O. insidiosus aggregates with thrips prey in the pepper flowers. Estimates of population numbers in the flower of field pepper appear sufficient for understanding the local dynamics of predator and prey and for estimating the benefits of biological control in scouting programs based on the predator to prey ratio. However, populations developing on the leaves may be important in allowing for persistence of thrips populations during periods of intense predation in the flowers.