ARS | Publication request: Classical biological control of invasive species: fighting fire with fire

Submitted to: Outlooks on Pest Management
Publication Type: Review Article
Publication Acceptance Date: June 2, 2011
Publication Date: June 30, 2011
Citation: Carruthers, R.I. 2011. Classical biological control of invasive species: fighting fire with fire. Outlooks on Pest Management. 22(3):122-128.

Interpretive Summary: Classical Biological Control is the use of living organisms, typically insects, pathogens or herbivores, to control other noxious pests that have been introduced into the country from other locations around the world. Such introduced pests are considered invasive species when they establish and spread in the areas of introduction where they often cause extensive damage to agricultural crops, forest, natural areas or other valuable resources. Many times these newly introduced pests grow exponentially in number in their adventive environment as they come free of their natural enemies (i.e. the organisms that limit their populations in the areas where they evolved). Most organisms are in a reasonable state of balance in their natural environment but when they escape their natural controls, numbers explode. USDA and other scientists have long used Classical Biological Control of reconnect pests with their natural enemies which often leads to significant reductions in pest numbers. A vigorous testing and evaluation process is conducted in determining what pests can be controlled in this manner, and this assessment goes hand in hand with a conservative regulatory process that ensures both effectiveness and safety in projects that use this approach for controlling exotic pests. This article gives an overview of the USDA’s efforts on Classical Biological Control and provides a number of example programs where this technology has been used to control both agricultural and environment pests, including both damaging insects and weeds.

Technical Abstract: Invasive species cost the US over $130 billion in losses and control costs every year. Exotic insects, weeds and pathogens are the primary invaders that frequently move across continents, exploding in numbers in areas where they have been newly introduced. There are many reasons that these pests reach such high densities and cause extensive damage, but one of the primary factors that exotic pests cause such a problem is that when they move, they escape other organisms that often keep their numbers low in the areas where they have naturally evolved. Biologists have long understood the regulatory affects of natural control and now use this understanding to develop and implement biological controls to help dampen the effects of newly introduced exotic pests. Classical Biological Control involves discovering where an exotic pest originated and then returning to that site to discover what organisms work in the local food web to limit their densities naturally. Using a combination of field and laboratory studies, USDA scientists evaluate potential biological control agents and then following a comprehensive set of testing and regulatory protocols, they work to introduce these agents carefully into the new environment where the introduced species has become a pest. This approach is outlined in this article and represents one of the most cost effective means of controlling insect and weed pests. Several example applications of biological control,including for the control of exotic weeds and insects, are presented, along with ways that these agents can be used alone or in ways that integrate their application with other methods of pest control. In many cases, these programs provide a cost benefit ratio of more than 1:100 in terms of their developmental cost versus accrued economic value.