Compatibility of Orius insidiosus (Hemiptera: Anthocoridae) with Amblyseius (Iphiseius) degenerans (Acari: Phytoseiidae) for control of Frankliniella occidentalis (Thysanoptera: Thripidae) on greenhouse roses

The compatibility of two commercially-marketed natural enemies of Frankliniella occidentalis (Pergande), an anthocorid bug, Orius insidiosus (Say), and a phytoseiid mite, Amblyseius (=Iphiseius) degenerans Berlese, was tested on cut roses, Rosa hybrida L. cv. 'Tropicana'. Our goal was to determine the extent to which intraguild predation could affect suppression of F occidentalis by this predator complex. We conducted laboratory experiments to examine: (1) effects of prey densities, prey composition, and crop structure on predation by adult O. insidiosus, (2) prey switching behavior in O. insidiosus, and (3) effects of Orius gender on prey preference. We found that Orius insidiosus will switch to the more abundant prey if presented with variable ratios of adult A. degenerans and immature or adult F occidentalis on flowers or foliage. If presented with prey in equal numbers, O. insidiosus preyed more on A. degenerans than adult F occidentalis but equally on A. degenerans and immature E occidentalis. Males and females of O. insidiosus showed similar patterns of predation, but females killed more prey than males. In greenhouse trials simulating thrips infestations of cut rose crops, we compared control of F occidentalis on roses with releases of both O. insidiosus and A. degenerans or only O. insidiosus. Roses with or without predators produced similar numbers of harvestable flowers, but roses with predators had fewer thrips than roses without predators. Releases of both predators did not enhance thrips control because roses with both predators had similar numbers of thrips as roses with only O. insidiosus. (C) 2007 Elsevier Inc. All rights reserved.