Interactions Between the Augmentatively Released Predaceous MiteGalendromus occidentalis(Acari: Phytoseiidae) and Naturally Occurring Generalist Predators

Abstract

Predatory mite releases can be an effective means of managing spider mites in many perennial cropping systems, yet little research has been performed in annual cropping systems. Herein we evaluate the compatibility of predaceous mite releases with the conservation of resident natural enemies in an annual agroecosystem. We quantify the impact of naturally occurring generalist predators, Geocoris spp. and Orius tristicolor White, and the omnivore Frankliniella occidentalis (Pergande), on the establishment of the western predatory mite Galendromus occidentalis (Nesbitt) and how these predator-predator interactions influence spider mite control. Field experiments showed that in the absence of generalist predators, released predatory mites can establish populations on cotton, increase in abundance through reproductive recruitment, and suppress spider mite populations. Hemipteran predators had a negative impact on predatory mite populations but generally improved spider mite suppression. The presence of F. occidentalis had no impact on predatory mite performance.