FEATURE ARTICLE

New Congressional Study Evaluates Biological Control

In recent years there have been several national studies that have evaluated the role of biological control and related technologies in pest management. Two very current studies are from the U.S. Congress and the National Academy of Sciences. The congressional report summarized here was released in October 1995; the NAS report was released in December and will be discussed in a future issue of MBCN.

The congressional study, requested by three congressional committees, was conducted by the Office of Technology Assessment (OTA). This 204 page report, Biologically Based Technologies For Pest Control, consists of an evaluation of biologically-based pest control methods and the use of such methods in integrated pest management.

The report indicates that pest management is moving toward practices that reduce reliance on conventional pesticides. Many of the reasons driving this change are discussed. For example, continuing public concern over the safety of pesticides has resulted in more rigorous screening, which has resulted in the loss of previously registered materials, as well as making it more difficult to get new materials registered. Further, the effectiveness of pesticides continues to be impacted by the development of resistance by some pests to some materials. At the same time, we are continuously facing new pest problems. The report indicates that there is a growing gap between available pesticide uses and the number of pests requiring control. This disparity will require a greater diversity of pest management tools. "This problem's significance has not been lost on national policymakers," the report states. "Both Congress and the executive branch have responded in recent years with initiatives related to providing pest management tools and expanding the implementation of integrated pest management (IPM)." It is also for this reason that Congress asked OTA to conduct a study of current usage and future potential for what the report calls "biologically based technologies" (BBTs) for pest control.

The report is organized into six chapters: (1) a summary, (2) establishing the context within which the report was developed, (3) a description of the five technologies, including assessments of current usage and obstacles to expanded use, (4) identifying possible risks of BBTs and discussing regulations to control risks, (5) a discussion of the pathways from research to implementation, and (6) commercial considerations. Therefore, the report does not provide in-depth assessments of each of the five general technologies or their more specific components. Instead, it discusses BBTs in broader terms, using specific examples from each technology as appropriate. I will briefly summarize chapters 3-5, attempting to concentrate on areas specifically relating to biological control.

The Technologies. The report covers five types of biologically based technologies: (1) biological control, (2) microbial pesticides, (3) pest behavior-modifying chemicals, (4) genetic manipulation of pest populations, and (5) plant immunization. Traditionally, insect biological control includes the first technology listed and parts of the second. I will first briefly characterize all five approaches included in the OTA report.

Biological control uses natural enemies (predators, parasites, pathogens, and, in the control of plant diseases, competitors) to suppress pest populations. The methods used include classical biological control (importation and permanent establishment of new natural enemies), augmentative biological control (periodic release of natural enemies as needed), and conservation of natural enemies (practices that enhance the benefits of existing natural enemies).

Microbial pesticides are commercial formulations of microorganisms that control pests by causing disease or by competing with plant pathogenic microorganisms. Large scale production and application characterizes microbial pesticides. Bacillus thuringiensis (Bt) is the most commonly used microbial pesticide.

Pest behavior-modifying chemicals exploit the chemicals that organisms use to communicate with each other or perceive their environment. Insect mating pheromones (sex attractants) have been used for disrupting mating (and therefore reproduction) of a few types of insect pests. Other types of behavior-modifying chemicals have also been used.

Genetic manipulation of pest populations requires the release into the pest population of genetically-altered individuals that interfere with the pest's reproduction or impact. An example is the use of sterilized males of screwworm fly, a serious cattle pest, which mate with the natural population of females, preventing the production of offspring.

Plant immunization uses microbes or chemicals to enhance levels of pest resistance in plants in ways other than through traditional plant breeding or genetic engineering. The report indicates that although there is much promising research in this area, there are no current practical applications in use.

The report provides somewhat sketchy data on the current usage of biological control and other BBTs. For example, it reports that 63 insect pests in the U.S. are under at least partial control because of classical biological control. It reports that growers use augmentative biological control in 10% of commercial greenhouses, on 19% of fruit and nut acreage, and 3% of vegetable acreage. Data on conservation of natural enemies are even more limited, but the report indicates that farmers consider natural enemies when making pesticide decisions on 37% of vegetable acreage, 22% of fall potato acreage, and 57% of cotton acreage. No numerical data are provided for the use of microbial insecticides, but it was noted that 45% of EPA's 1994 registrations of new active ingredients consisted of microbial pesticides and insect pheromones. The report states that "a wide variety of commercial microbial pesticides are currently under development."

There is also some discussion of biological control in urban and suburban areas. Several commercial products are available for use by homeowners and are popular with those people who want to avoid contact with insecticides. However, there has been limited use of classical biological control in the landscape, even though many serious pests were introduced from other countries.

Chapter 3 also includes a discussion of the obstacles to increased usage of BBTs. A major obstacle is the scope of technologies that can be delivered to the pest manager; that is, there currently are not BBTs for many pest problems. The report states that such "technical . . . obstacles can be addressed only by adequate adjustment of the [federal] research agenda and by provision of mechanisms to ensure that research results become available for field applications." Specific research priority areas are listed.

Risks and Regulations. This chapter discusses the risks associated with BBTs, compares these risks to other pest control methods such as conventional pesticides and discusses the federal regulatory framework design to minimize risks. The report assesses the potential risks of biological control, if not properly regulated, as follows.

Classical biological control may result in some adverse impacts on nontarget organisms, but there is no known risk to humans. Documented environmental impacts include reduction in population levels and even extinction of nontarget organisms. However, the report indicates that many of these cases occurred early in the history of biological control before regulatory processes were in place and at a time when there was less concern about the fate of indigenous organisms.

Augmentative releases of predators and parasites may also impact nontarget organisms, but no specific cases were listed. The only known human risk is to workers in natural enemy production facilities who may develop allergies. Also, for those few natural enemies that are field collected (rather than lab-propagated) for sale and subsequent release, there may be risks of spreading contaminants and of depleting the natural enemy population from the areas of field collection. Both situations exist with the convergent lady beetle which is the species commercially available.

Conservation of natural enemies was considered by the report to have "probably insignificant" environmental risks and no known risk to humans. Microbial insecticides may have certain environmental risks, including effects on nontarget organisms and their predators. Bacillus thuringiensis (Bt) in particular, when used in more complex natural communities such as forests, may result in short-term reduction in numbers of larvae of nontarget moths and butterflies. This impact may spread through the food web by depriving predators such as birds of their normal prey. Another possible risk with the use of microbials is the development of resistance to the product by the pest; this has occurred in a few cases with Bt. The risk of microbials to humans is considered by OTA to be minimal in the general population, but there are some data to suggest some agents may be infective to immuno-compromised individuals.

The report notes that there is very strong opinion in the scientific community that risks from BBTs are dwarfed by the risks from conventional pesticides, and "most BBTs have a favorable health and environmental profile." The report indicates that chemical pesticides raise significant issues with consumer and occupational health and environmental safety, whereas BBTs primarily affect native organisms which are of relatively recent concern in the U.S. The report concludes that "in the real world . . . many of the possible risks from BBTs pale in comparison with the benefits of use."

There is no federal statute that directly deals with BBTs; even biological control specifically has no single regulatory agency or process. Instead, different aspects of regulatory oversight of BBTs are handled variously by the USDA, EPA, FDA, and the Department of Interior. The OTA report indicates that there are flaws, inconsistencies, and other weaknesses in the regulatory process. Some of these weaknesses impede the implementation of BBTs whereas others may not be adequately protecting against environmental or human health risks. The report suggests several options for Congress to consider to change the regulatory process. Space constraints limits discussion of these options, but several would impact classical and augmentative biological control, and the registration and use of microbial pesticides.

From Research to Implementation. The report indicates that public funding on BBT research in 1995 was $160 million, of which $130 million was federal and $30 million was state. Most federal research dollars are spent by USDA scientists in the Agricultural Research Service. Some federal money and most state research dollars are used by the state Land Grant universities. The report indicates that the research ". . . expenditure appears to be largely uncoordinated and to lack adequate prioritization." The report also states ". . . that basic research on BBTs is poorly linked to on-the-ground applications, in part because no federal research agency takes responsibility for this function." The report states that biological control, in particular, has suffered from lack of coordination amongst state and federal agencies.

This chapter also evaluates the role of Cooperative Extension in the transfer of knowledge that is necessary to implement biologically-based approaches to pest control. The report concludes that although Extension has historically been important in providing information on other general approaches to pest control, especially the use of conventional insecticides, Extension has not historically been strong in delivery of information on biological control or other BBTs. Although the reasons for this are complex, the report is probably correct in its assessment that Extension is ". . . financially strapped and the workforce spread thin among multiple responsibilities." Many extension personnel, especially at the county level, are neither broadly nor deeply trained in pest management, and formal training in BBTs is often lacking. Further, because of limited application research, extension personnel have little reliable information to deliver on BBTs and therefore ". . . feel caught in the middle between a clientele who ask for pesticide alternatives and a research pipeline that fails to deliver effective, ready-to-use technologies." The report indicates that in most areas private consultants play a greater role than Extension in the implementation of BBTs. This is not without its problems, however. Many private consultants are representatives of specific companies that have a product to sell, such as the agrichemical industry. Most private consultants are not trained in the use of BBTs. Also, private consultants will continue to need access to new technologies developed in both the public and private sectors.

Another of the obstacles to acceptance of BBTs by farmers is that the benefits of such technologies tend to be social and environmental, and the economic benefits to the individual grower may not be as obvious, especially if the technologies appear to be more costly or complex to implement. Aspects such as avoidance of pesticide resistance and natural enemy conservation may not appear to be immediately tangible benefits to the farmer.

This chapter also proposes several options for possible congressional action; the following are some that are of relevence to biological control: better coordination of BBT research; increase funding for implementation research; establish a coordinating agency for biological control activities; increase support of biological control within the National Research Initiative (ironically, this program has been cut from the federal 1996 budget, but then, so has OTA!); improve documentation of natural enemy introductions in classical biological control; and increased funding of monitoring programs for higher-risk BBTs.

I have attempted to provide an objective, uncritical review of the OTA report. Although in places the report seems sketchy, that probably only represents the type and quality of information available. Indeed, the report seems well researched, with over 430 references listed. Different readers will have different opinions and conclusions about the report. My assessment is that OTA generally supports biological control and other BBTs, but recognizes that the regulatory process is necessary, and that constraints, such as the availability of specific BBTs for specific pest problems, are real. The report seemed to support increased funding for basic and implementation research. Although it recognized information transfer to the farmer as being important and defficient, I was disappointed by the lack of suggestions to Congress for improving the flow of information through public channels such as Extension.

To purchase a copy of this report (# OTA-ENV-636), write to:

The price is $14, post-paid. Dan Mahr, University of Wisconsin - Madison


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