ARS | Publication request: DIFFERENTIAL PREDATION BY THE GENERALIST PREDATOR ORIUS INSIDIOSUS ON CONGENERIC SPECIES OF THRIPS THAT VARY IN SIZE AND BEHAVIOR

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 18, 2006
Publication Date: June 1, 2006
Citation: Reitz, S.R., Funderburk, J.E., Waring, S.M. 2006. Differential predation by the generalist predator Orius insidiosus on congeneric species of thrips that vary in size and behavior. Entomologia Experimentalis et Applicata. 119:179-188.

Interpretive Summary: Interpretive Summary Frankliniella flower thrips are key pests of many vegetable crops, including peppers. Because chemical pesticides are not an effective strategy for controlling these pests in vegetable crops, the use of biological control agents is receiving greater interest. Generalist predators can be effective biological control agents, but the impacts of a predator on different pests may be affected if the predator shows preferences for one prey pest species over another. Scientists with the USDA, ARS, Center for Medical, Agricultural and Veterinary Entomology in Gainesville and Tallahassee, FL, and the University of Florida have found that the minute pirate bug, Orius insidiosus is an effective predator of the western flower thrips (Frankliniella occidentalis) and the Florida flower thrips (Frankliniella bispinosa), yet it preferentially preys on the western flower thrips. These results suggest that Orius insidiosus would be able to suppress populations of the western flower thrips in pepper fields sooner than it would be able to suppress populations of Frankliniella bispinosa. A better understanding how predators interact with different prey species will lead to the more effective use of generalist predators as biological control agents of insect pests in vegetable crops.

Technical Abstract: Technical Abstract Generalist predators can show preferences for certain prey types. These preferences can result from active choice by predators or through passive mechanisms that make certain prey more vulnerable to predation than others. Consequently, differential predation can alter the population dynamics of closely related prey species and community structure. We investigated interactions between the generalist predator Orius insidiosus and adults of two species of thrips, Frankliniella bispinosa and Frankliniella occidentalis, and interspecific differences between these prey species that could affect predation by O. insidiosus. When O. insidiosus were offered either F. bispinosa or F. occidentalis as prey in single species trials, there were no significant differences in the number of prey captured. However, O. insidiosus had more encounters with F. bispinosa than with F. occidentalis. In arenas with equal numbers of both species, O. insidiosus had more encounters and captures of F. occidentalis than of F. bispinosa. In large arenas with two pepper plants, O. insidiosus preyed on more F. occidentalis than on F. bispinosa. These results indicate that O. insidiosus can prey on adults of both thrips species, but that in mixed species groups, this predator preferentially captures F. occidentalis. Although F. occidentalis are much larger than F. bispinosa, the greater locomotion and movement of F. bispinosa allow it to avoid interactions with O. insidiosus and evade predation better than F. occidentalis. Consequently, the observed preference of O. insidiosus for F. occidentalis is not exclusively a function of active selection by the predator but arises from inherent differences among prey. Because F. occidentalis is more vulnerable than F. bispinosa to predation by O. insidiosus, this differential predation can affect the temporal dynamics of these species, and allow populations of F. bispinosa to persist longer into the growing season than populations of F. occidentalis.