Approaches of Biological Control: Augmentation

Augmentation biological control basically means adding natural enemies, either where they are not present, or are present at small numbers. Two different approaches to augmentation are either inoculation of small numbers of natural enemies, or inundating with large numbers. The two approaches have very different aspects and align with different objectives of biological control. With inoculation, one begins with a small number and allows the natural enemy populations to increase over time. In this case, the pest population does not decrease quickly (i.e., reduction), but can either be prevented from reaching pest status or the population increase is delayed. On the other hand, with inundation, one introduces a large number of natural enemies, with the intention of reducing the population quickly. Inundation has a greater associated cost, as the large number of natural enemies either must be purchased or reared. Inundation is less expensive, but also doesn't provide a remedial solution.

There are over 100 species of natural enemies available to purchase in North America for augmentation biological control, sold by over 100 companies and insectaries. A useful publication produced by the California Environmental Protection Agency lists the species and vendors (Hunter 1996), and is recommended to the reader.

Augmentation has been used more extensively in greenhouse and interior settings than in crop settings, but there are examples of successful use in nearly all settings.