The state of commercial augmentative biological control: plenty of natural enemies, but a frustrating lack of uptake

Biological control is the use of an organism to reduce the population density of another organism. Biological control has been in use for about two millennia, and has become widely used in pest management since the end of the nineteenth century (DeBach 1964; van Lenteren and Godfray 2005). The following types of biological control can be distinguished: natural, conservation, inoculative (=classical) and augmentative biological control. Natural biological control is the reduction of pest organisms by their natural enemies and has been occurring since the evolution of the first terrestrial ecosystems some 500 million years ago. It takes place in all of the world’s ecosystems without any human intervention, and, in economic terms, is the greatest contribution of biological control to agriculture (Waage and Greathead 1988). Conservation biological control consists of human actions that protect and stimulate the performance of naturally occurring natural enemies (Gurr and Wratten 2000). In inoculative biological control, natural enemies are collected in an exploration area (usually the area of origin of the pest) and then released in new areas where the pest was accidentally introduced. The aim is that the offspring of the released natural enemies build up populations which are large enough for suppression of pest populations during many subsequent years. This type of biological control has been used most frequently against introduced pests, which are presumed to have arrived in a new area without their natural enemies. As it was the first type of biological control practised widely, it is also called “classical” biological control (DeBach 1964). In augmentative biological control natural enemies are mass-reared in biofactories for release in large numbers to obtain an immediate control of pests. The history of commercial mass production and sale of natural enemies spans a period of roughly 120 years. In some areas of agriculture, such as fruit orchards, maize, cotton, sugarcane, soybean, vineyards and greenhouses, it has been an environmentally and economically sound successful alternative to chemical pest control (van Lenteren and Bueno 2003). Natural, conservation and inoculative biological control are generally carried out using public funding, whereas augmentative biological control is often a commercial activity because of the need of mass production and large scale regular releases of natural enemies.

Inoculative biological control is estimated to be used on 10% of land under cultivation (Bale et al. 2008) and, over the last 120 years, 165 pest species have been brought under long-term control (Cock et al. 2010). Cock et al. (2010) estimated that worldwide 170 species of invertebrate natural enemies are produced and sold globally for periodical release in augmentative biological control of more than 100 pest species on about 0.4% of land under cultivation. Augmentative biological control is operated by state-funded or commercial biofactories (van Lenteren and Bueno 2003).

Currently, augmentative biological control is in a critical phase, even though during the past decades it has moved from a cottage industry to professional production, which has identified many efficient species of natural enemies, developed quality control protocols, mass production, shipment and release methods, as well as adequate guidance for farmers (van Lenteren 2003; Cock et al. 2010). Large recent successes, such as the virtually complete replacement of pesticides by predatory mites to control thrips in Spain, show how well biological control can function (Merino-Pachero 2007) and literally saved vegetable production. However, this form of biological control is applied on a frustratingly small acreage, even though biological control has been considered the environmentally safest and most economically profitable form of pest management (e.g. DeBach and Rosen 1991; Cock et al. 2010). Thus, the question emerges “which factors prevent a much larger use of augmentative biological control?”

This paper first provides information about the 230 species of natural enemies which are used presently in augmentative biological control. Next, I explore why this type of biological control is not used more often. Finally, I summarize developments which are expected to lead to increased application of augmentative biological control.