The Biological Control Methods
The pest management tactics of biological control are divided into three categories or methods: Introduction (Classical), Augmentation, and Conservation.
The images above show four people who undoubtedly had the greatest impact on the early development of biological control as a scientific discipline and effective method for pest management. Left to right they are Charles Valentine Riley, Harry Scott Smith, Harold Compere and Paul DeBach. C.V. Riley was the United States Department of Agriculture's top entomologist from 1881 to 1894 and the first curator of the Smithsonian's insect collection in 1885. He was also the first to propose the intentional intercontinental movement of a predator to help control an accidentally introduced agricultural pest. Harry Scott Smith is given credit for coining the phrase "biological control", but more importantly served in two roles: as an administrator during the development of California's Citrus Experiment Station and the University of California, Riverside and a major player in early biological control research. Harold Compere is one of biological control history's most accomplished foreign explorers. His efforts helped bring natural enemies into California that eventually controlled many significant agricultural pests. Paul DeBach was a University of California, Riverside professor and researcher. Notable accomplishments included writing the first textbook on biological control, conducting the first intercontinental shipment of natural enemies using an airplane and educating an enormous number of PhD students in biological control methods. Click on their names above for more information, or check out their Wikipedia pages.
Introduction is the process of safely introducing a small population of an upper trophic level species to restore ecological balance to a system being disrupted and dominated by a pest population.
Introduction is a method reserved for research scientists associated with a university or the USDA that have access to a federally approved quarantine facility. There is a complex of highly trained personnel assembled for an introduction program, but it usually starts off with an accident. The accident being the unintentional movement of a few individuals of a species into an area where they previously never occurred. An event usually referred as an invasion. Invasive species are considered one of the top threats to agricultural production in California, as well as to its natural and urban environments.
When a small group of organisms gets introduced to a new area there are several possible fates for them. The one most feared is that the population will establish, successfully feed and breed on a crop important to us, and its numbers grow wildly out of control. This nightmare scenario happens all too frequently. Recent examples in California include Asian citrus psyllid, Olive fruit fly, polyphagous shot hole borer, and red imported fire ant. And its not just insects, there is yellow star thistle, Veld grass, Saharan mustard, and plant pathogenic diseases as well.
The basic idea is to send scientists back to the place of origin of the invasive organism, locate populations there and determine if those populations are kept in check and not considered a pest. If so, the next step is to find out what is keeping their numbers in check and return with that natural enemy to a quarantine facility near the invaded area for further study.
If intensive research shows that the natural enemy is suitable for release, then a permitted introduction is made against the invasive pest. That is where the "introduction" label for this biological control method comes from.
What the method accomplishes is to recreate the ecological balance observed in the native home, in the newly invaded area.
For more reading see Richard Sawyer's book: To Make Spotless Orange.
Augmentation is the amplification of a beneficial organism's populations at the appropriate time and place. The beneficial organism requires augmenting its numbers because some intrinsic or extrinsic factor makes it incapable of regulating the target pest population to our satisfaction.
Augmentation is a method that is available for anyone's participation. The key is having the appropriate numbers of the natural enemy best suited to the pest problem. Where to get natural enemies? There are two types of sources, one is a commercial insectary and the other is a grower cooperative.
There are about a dozen commercial insectaries in the US and several in many other countries. International companies, like Koppert, Inc. provide field technicians in the US to provide advice to growers; they also data on complementary natural enemies and compatibility tables for using natural enemies in an integrated pest management program (http://side-effects.koppert.nl/). See Koppert's website here: http://www.koppert.com/.
Another excellent example of a full service insectary providing growers the much needed technical help in deploying and assessing natural enemy effectiveness is Bugs for Bugs in Queensland, Australia: http://www.bugsforbugs.com.au/.
The grower-cooperative type of insectary is unique, and only one remains in business presently -- Associates Insectary, Inc. View their website and see the products they have available here: http://www.associatesinsectary.com/. They too have field technicians and a full range of advice for using the natural enemies to ensure a good outcome for the money spent. Read more on the history of the Fillmore Protective District, citrus biological control and the development of commercial biological control insectaries...
For a comprehensive listing of companies that are beneficial insect producers and general information on biological control please visit: http://anbp.org/index.php
Conservation has two subcategories: limiting use of broad spectrum insecticides and enhancing the landscape to provide appropriate resources to enhance natural enemy activity.
Conservation too, is a method that is available for anyone's participation. But this type of conservation is all about conserving one type of resource - natural enemies.
The differences between the methods includes the breadth of their focus. Introduction looks at fixing one species of pest with typically one natural enemy. Augmentation can target multiple pest/natural enemy pairings contemporaneously in a cropping system. And conservation examines the cropping system as a whole...all of the interconnected flora and fauna.
On the chemical side of natural enemy conservation, the main idea is to reduce the hazards of chemical applications to natural enemies present in the system. If they are working to reduce pests for free, why do something to impede or harm them? In the past the focus was in reducing the use of broad spectrum pesticides - those chemicals that indiscriminately kill any kind of insect they contact. From the 1960s through the 1980s there wasn't much variety in the kinds of pesticides registered for use in cropping systems, so that was challenging to achieve. But since the 1990s there have been a considerable number of new chemical classes of pesticides that are more selective in their targets, thus limiting their negative impact on natural enemies. Read here for more information. But even these new selective pesticides are not free of negative impacts. Click on the file below for a very compelling example.
Enhancing the landscape or otherwise manipulating the environment to aid natural enemies in pursuit of their prey is a highly complex ordeal without much concrete research to back up suggestions and ideas. It's an area that takes experimentation and commitment to make it work. There is a federal agency, ATTRA, that has produced several key references to help guide people in enhancing biological control in agriculture cropping systems. ATTRA - A National Sustainable Agriculture Assistance Program - was developed and managed by the National Center for Appropriate Technology (NCAT) and their website can be found here: https://attra.ncat.org/. The pdf of their publication "Farmscaping to Enhance Natural Enemies" can be downloaded here.