Classical Biological Control of Invasive Species: Fighting Fire with Fire
Abstract:Invasive species introductions are a very large and increasing problem worldwide, with losses estimated at nearly 5% of the world's economy. In the United States, these exotic pests are estimated to cause $130 billion in losses and control costs every year. As a scientist working in the field of integrated pest management (IPM) for over 30 years, the author has had the opportunity to work on many different aspects of invasive species control, from the development of pesticide control procedures to the use of biological agents for aiding their management. In most circumstances, it was necessary to combine several different methods, taking a more holistic IPM approach to manage these pests sustainably. During his career, he has also had the chance to work in a diversity of agricultural landscapes including crop production lands and rangelands and in natural areas such as forests and riparian corridors. Currently he is working to manage invasive plants in waterways, using all possible means of control. Through these experiences, he has become a firm believer of “understanding your enemy” and then developing management strategies that take advantage of key weaknesses in the biology of the target pest. Many times such strategies exploit the use of beneficial organisms, or in other words “biological controls”. There are several recognized methods of biological control including, natural control where conservation of beneficial organisms is the primary goal or more active techniques such as augmentation of natural enemies and/or the introduction of exotic beneficial organisms, that is often referred to as Classical Biological Control. In the author's experience, biological control is one of the most powerful methods in the IPM toolbox and we need to use this technology, whenever and wherever possible. Following their introduction, new invasive pests often explode in number, growing exponentially in their new adventive habitat. This high growth rate allows the pest to increase its density rapidly at the point of introduction, and then expand geographically via dispersal. Many theories have been proposed by invasive species biologists to explain this rapid growth phase, with escape from natural enemies being one of the most commonly cited reasons for such explosive increases. It has often been shown that in their areas of origin most pests are fed upon by a complex guild of other organisms (natural enemies), many of which exert substantial mortality (top-down population regulation) and limit their host's abundance, thus keeping their populations below damaging levels. Clearly, many other factors (limiting abiotic conditions, limited food availability (bottom-up regulation)), may affect the ability of each species to develop and increase at the high rates found in their introduced range, however, lack of natural enemies is a very common occurrence that pest managers should better understand and exploit. Following new pest introductions, regulatory authorities often attempt to eradicate invasive species. If eradication efforts fail or seem impractical, control procedures are usually implemented by local farmers, ranchers and other land/waterway managers each attempting to control the invader on their own. An alternate strategy that has worked well in many situations has been the development and area-wide application of Classical Biological Control (CBC).
Document Type: Research Article
Publication date: June 1, 2011
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