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Letter from the Editors
The Scope of Resistance in North America
In 2001 the world's pesticide market exceeded $34 billion while in the US it is projected to have exceeded $11 billion. It has been estimated by Pimentel et al. (2002) that pesticide resistance surpasses $1.4 billion in environmental, ecological, and human impact costs. What are some of the features driving resistance development in North American societies? Consumerism certainly drives much of the globalism and free-market decisions in North America today. Bi-lateral trade agreements and falling tariffs have opened the way to new markets and products. Both pesticide regulations and the enactment of the Food Quality Protection Act (1996) are seen by some as emergent properties of consumerism and the environmental movement. Consumers demand blemish-free fruit and vegetables. Federal and state regulations require wholesome and labeled products as well as numerous other quality-related characteristics. Thus, consumerism in its myriad forms has swiftly overtaken outdated forms of production, marketing, and sales of agricultural products. Consumers have power in the market place today, and their power is partially translated into increased pressure toward "perfect" product quality that can only be delivered through increasingly intense pest management systems.
The environmental movement has also fostered new awareness and a drive toward new legislation and regulations targeting pesticides in agriculture and health protection. Environmental concern has also been linked to the consumer movement in western societies and together they are global in scope, extending even into third world countries. Environmentalism transects the demographics of western societies and strongly affects the regulatory policies in the U.S., Canada, and Mexico. It is projected that environmentalism will extend well into the twenty-first century.
Environmentalism and consumerism together have several pest management and resistance management impacts. The rise of global marketing, consumerism, and environmentalism together medicate much of western society's modern conscience. First, North American societies source products globally and transport these goods rapidly into the country. Second, more than 60% of North American pests historically have been introduced, with new introductions occurring almost weekly. At this rate, will North American societies eventually import most of the ecologically compatible global pest species despite our phytosanitary barriers?
Emerging with consumerism on a global scale, market access through non-tariff phytosanitation barriers has become a gauntlet that every entrepreneur must overcome. Both the introduction of invasive species and phytosanitation requirements dictate additional pesticide applications and potentially accelerate resistance selection.
Within this context is resistance, where the genetic-based adaptation of pests to man's effort to control them has become more and more important as globalism, consumerism, and market access concerns drive pesticide use. From this point of view, it is not difficult to believe that resistance problems will plague agriculture and human and animal health protection for the foreseeable future.
As editors, we represent applied ecology and insect toxicology. In our view, it is difficult to look past the inference that resistance is a symptom of a dysfunctional ecosystem. That is, agricultural production systems are often defined as disrupted ecosystems (Southwood, 1978). Resistance can logically be viewed as a symptom or indicator of an ecosystem that has been disrupted beyond its natural equilibrium, resulting in an ecologically negative outcome. Therefore, resistance is a consequence of pesticide overuse, or selection susceptibility genes in a utilitarian and reductionist sense.
This perspective could also be adopted in human and animal health protection where the problem with anti-microbial resistance has surfaced in the popular media repeatedly. It is with some irony that media would focus on antibiotic resistance and human health while less immediate resistance issues with insecticides, herbicides, and fungicides in food production rarely surface. Insecticide, acaracide, and filaricide resistance is also a critical issue for human health protection in North America but the media surprisingly overlooks it too. The media even ignores efforts by the US Centers for Disease Control (CDC) and the World Health Organization (WHO) to track various disease vector resistance development in the Americas, Asia, and Africa. With the recent media attention in North America on the introduction of the mosquito-vectored West Nile Virus into suburban and urban population centers, one might expect a somewhat broader articulation of the fragile nature of human health protection, including vector resistance. A further irony, some might note, is that North American media in concert with environmental and consumer movements would skewer certain insecticide use like organophosphates in food production, yet approve - or even champion - the direct exposure of large numbers of people during mosquito vector control operations. Apparently, it is not appropriate to expose people to minuscule residues in the diet, but inhalation and contact exposure for human health protection is not newsworthy.
When addressing the scope of North American resistance development, new regulations dealing with resistance are of critical interest. For example, with the promulgation of regulations governing the registration of genetically modified plants containing insecticidal proteins, resistance management plans were required as a prominent portion of the registration portfolio. With one exception, all of the current conditional registrations for genetically modified plants containing insecticidal proteins have a resistance management plan based on high dose and refugia strategies (the single exception is Mom 863 for corn rootworm control).
The European Union has also recently taken some recent strides to require resistance management guidelines in its regulatory system. The EU-EPPO-PP1/213(1) guidelines require resistance risk assessment, development, and implementation of a resistance management plan and baseline monitoring of resistance for all new registrations within the EU. The 1996 Food Quality Protection Act (FQPA) also has a provision for resistance monitoring contained in its details. Essentially this prescription for resistance monitoring is worded much like a series of recommendations of the US Board on Agriculture of the National Research Council, one of which states that, "Federal agencies should support and participate in the establishment and maintenance of a permanent repository of clearly documented cases of resistance" (Dover and Croft, 1986). However, to our knowledge no divisional program within USEPA has ever followed up on this part of the FQPA law other than voluntary reporting of resistance development by registrants.
Presumably one measure of the impact of recent regulations on the availability of resistance management tools is the number of different formulations, pesticide and biopesticide modes of action, effective natural enemies, and other management strategies, tactics, and tools. Approximately 6,000 pesticides have been cancelled or significantly mitigated since the passage of the FQPA. On the other hand, the FQPA and related activities of the USEPA have accelerated the registration of reduced-risk pesticides and organophosphate alternatives. Unfortunately however, this legislation has also practically eliminated the experimental use permit process whereby land grant universities, private technical service providers, and commodity researchers have historically adapted new pesticide tools to various production systems. In addition, the FQPA has provided an array of new risk-science developments estimating the aggregate exposure to pesticides that exhibit common modes of action, the cumulative human pesticide exposure over a lifetime, and the impact of endocrine disruption on non-target organisms. Potentially all of these risk-science innovations could have unique or integrated impacts on resistance and resistance management in North America as the USEPA evolves these policies.
As previously mentioned, resistance is a genetic-based decrease in the susceptibility of a population to a control measure. It has been observed across herbicides, fungicides, and bactericides, as well as insecticides and miticides. An array of evolving pest biotypes or races has also overcome conventionally selected host plant resistance crop varieties. Perhaps even cultural control strategies like crop rotation may be overcome by genetic adaptation in a pest. An array of adapted ecosystems, particularly resistant soils, has also evolved to pesticides. The economic, social, and environmental consequences for the various types of resistance include pest control failures, disrupted pest management systems (including limitations in the development of integrated pest management options), and increased pest control costs. Increased pest control costs have variously been classified as 1) pest managers forced to resort to newer, higher-priced pesticide alternatives and 2) additional applications.
Certainly, there are arrays of environmental, social, and disrupted functional ecosystem consequences of increased pesticide use induced by resistance. Functionally, disrupted ecosystems and environmental impacts could be measured in increased off-target effects on bio-diversity and/or endangered species. Additional social impacts may include consequences on humans from increased pesticide residues, worker exposure, or increased disease spread where vector control is diminished as a result of resistance.
In summary, globalism and environmentalism will likely continue to impact the availability of pesticides as well as the social and economic determinants that will dictate overuse of pesticides leading to resistance. Heightened concerns over homeland security, particularly in the United States, may have collateral effects in terms of fighting bio-terrorism with additional pesticide use. Certainly the emergence of biotechnology and genetically modified organisms with various pest selection processes could result in further expansion of resistance problems. On the other hand, monitoring and diagnostics in resistance management should improve dramatically with the application of new high-through-put technology developed initially for HIV/AIDS and cancer detection. In addition, the pesticide industry, though market and regulatory incentives, is beginning to deliver an expanding array of novel and ecologically softer pesticides. This fresh collection of new modes of pesticide action should allow pest managers a greater diversity of management tools to focus on target pests, thereby reducing the rate of resistance selection. Obviously the dissemination of various regulations will continue to impact the availability of resistance management tools.
Certainly, society is witnessing the rapid and expansive response of the private sector to reduced-risk and organophosphate-alternative incentives through the USEPA. One might only speculate on the development of new resistance management strategies, tactics, and tools if some of the focus and resources currently employed to regulate pesticides in North American societies are actually allocated to monitoring and measuring resistance, the loss of susceptibility in resistant-prone species, or the dysfunctional ecosystems resulting from resistance development. The CAST Resistance Conference highlighted several efforts to document resistance development in weeds, fungicides, and arthropods. These efforts are essential from our prospective, because "what gets measured gets managed."
Supported By:
Editors:
Mark
E. Whalon
Robert M. Hollingworth
Area Editors:
Plant Pathology
Margaret Tuttle McGrath
Herbicide
Jonathan Gressel
Maintained
by:
Theresa A. Baker