Ecology of Rearing:
Quality, Regulation, and Mass Rearing
Linda A. Gilkeson
A 1992 list of biological control agents sold commercially in North America listed 105 species of arthropods to control arthropods and 27 species of arthropods to control weeds ( Anon 1992). This is more than double the number of arthropods listed in 1989 ( Bezak 1989) and shows the rapid growth in the commercial biological control industry. Although several established insectaries in North America have been producing large quantities of biological control arthropods for more than a decade, it is only within the past four years that industrial-scale production facilities have been built in North America. These produce phytoseiid mites and Trichogramma spp. parasitoids for use over very large areas. For example, the phytoseiid mite Phytoseiulus persimilis is used to control spider mites in strawberries in California ( Grossman 1989), and it may be feasible to release them from the air over corn acreage ( Pickett et al. 1987). With the increasing scale of inundative biological control programs, greater numbers of arthropod biological control agents are reared in semi-industrial conditions that differ in many respects from the natural conditions of the intended release site. At this time, the majority of mass- reared species are used in greenhouses, in an artificial environment similar to mass-rearing conditions. They are mostly used on annual crops grown in a protected climate that changes relatively little, with the exception of day length, throughout the season. Crop plants are generally uniform, and predators are distributed manually by greenhouse staff. With greater application outdoors, however, questions arise about the behavior, genetics, health, and overall quality and suitability for release of the arthropods reared in mass-production facilities. This chapter describes some of the goals and constraints of commercial mass production of arthropods, how those goals may conflict with requirements of biological control programs, and quality issues as they apply in mass production of arthropod natural enemies.