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Biological Control 52 (2010) 8–16

Contents lists available at ScienceDirect

Biological Control
journal homepage: www.elsevier.com/locate/ybcon

Review

Biological control of arthropod pests using banker plant systems: Past progress and future directions
Steven D. Frank *
Department of Entomology, North Carolina State University, Campus Box 7613, Raleigh, NC 27695-7613, USA

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The goal of banker plant systems is to sustain a reproducing population of natural enemies within a crop that will provide long-term pest suppression. The most common banker plant system consists of cereal plants infested with Rhopalosiphum padi L. as a host for the parasitoid Aphidius colemani L. Aphidius colemani continually reproduce and emerge from thebanker plants to suppress aphid pests such as Aphis gossypii Glover and Myzus persicae Sulzer. Banker plant systems have been investigated to support 19 natural enemy species targeting 11 pest species. Research has been conducted in the greenhouse and field on ornamental and food crops. Despite this there is little consensus of an optimal banker plant system for even the most frequently targetedpests. Optimizing banker plant systems requires future research on how banker plants, crop species, and alternative hosts interact to affect natural enemy preference, dispersal, and abundance. In addition, research on the logistics of creating, maintaining, and implementing banker plant systems is essential. An advantage of banker plant systems over augmentative biological control is preventativecontrol without repeated, expensive releases of natural enemies. Further, banker plants conserve a particular natural enemy or potentially the ‘right diversity’ of natural enemies with specific alternative resources. This may be an advantage compared to conserving natural enemy diversity per se with other conservation biological control tactics. Demonstrated grower interest in banker plant systemsprovides an opportunity for researchers to improve biological control efficacy, economics, and implementation to reduce pesticide use and its associated risks. Ó 2009 Elsevier Inc. All rights reserved.

Article history: Received 30 March 2009 Accepted 29 September 2009 Available online 6 October 2009 Keywords: Alternative prey Aphidius colemani Aphidoletes aphidimyza Aphis gossypii Augmentativebiological control Bemisia tabaci Conservation biological control Encarsia formosa Greenhouse Integrated pest management Myzus persicae Open-rearing system Release strategy

1. Introduction Interest in biological control has increased over recent decades for many reasons (van Lenteren and Woets, 1988; Bailey et al., 2009). First, a greater appreciation for environmental stewardship among regulators,growers, and the public has promoted development of more sustainable farming practices (Kogan, 1998). Second, a number of arthropod pests have developed resistance to one or more pesticides leaving growers to search for alternative management strategies (McCaffery, 1998). Finally, consumers increasingly demand products that are grown in a sustainable manner and are free of insecticide residue(Dabbert et al., 2004). Despite this, growers have been slow to adopt biological control as part of their pest management program. For example, biological control is practiced in just 5% of the estimated 741,290 acres of greenhouses worldwide (van Lenteren, 1995). The primary factors affecting adoption of biological control are efficacy, predictability, and cost (Parrella et al., 1992; Van Driesche andHeinz, 2004). Banker plant or open-rearing systems combine aspects of augmentative and conservation biological control in an attempt to
* Fax: +1 919 515 7746. E-mail address: sdfrank@ncsu.edu. 1049-9644/$ - see front matter Ó 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.biocontrol.2009.09.011

mitigate these factors. Banker plant systems typically consist of a non-crop plant that is...