PREDATORY BEHAVIOR AND PREY-STAGE PREFERENCES OF STIGMAEID AND PHYTOSEIID MITES AND THEIR POTENTIAL COMPATIBILITY IN BIOLOGICAL-CONTROL

Although the role of phytoseiid mites as predators of the European red mite, Panon-ychus ulmi (Koch), on apple is well established, the role of another family of European red mite predators, the stigmaeids, is not as clearly understood. We compared predatory behavior and prey-stage preferences of the stigmaeid Zetzellia mali (Ewing) and the phytoseiid Typhlodromus caudiglans (Schuster) in the laboratory. The only predator-predator interaction we found to be potentially important was consumption of phyto-seiid eggs by stigmaeids. Given a choice of equal numbers of both European red mite eggs and phytoseiid eggs, Z. mali consumed 38% phytoseiid eggs. Eggs and quiescent larval stages of European red mite were preferred by Z. mali, but active larval stages also were consumed. By contrast T. caudiglans preferred active forms to quiescent forms and eggs, and was able to consume adult forms. Although Z. mali was found to be slower, less active, and less voracious than T. caudiglans, Z. mali produced more eggs for a given number of prey consumed than did T. caudiglans. These behavioral and prey-stage preference differences should enable phytoseiids and stigmaeids to be compatible in the short term (within one generation). © 1990, Entomological Society of Canada. All rights reserved.