Concern continues to rise over the adverse effects of the excessive use of chemically based agricultural pesticides, including herbicides, insecticides, nematicides, and fungicides. Important members of the U.S. agricultural scientific, producer, and policy communities have added their voices to those in the environmental, consumer, and public health arenas in pointing to the need for more benign and cost effective methods and systems of pest management and control. Indeed, the urgent need to further enhance the efficacy and use of such varied, yet interrelated, approaches to pest control as pathogens, predators, and parasites (traditional biological control), and such biologically based techniques as host plant resistance, natural plant products, semiochemicals, and autocidal methods, is now widely recognized in most agricultural circles.

Biological control is defined broadly as the “use of natural or modified organisms, genes, or gene products” to reduce the effects of pests and diseases. Physical control is the use of tillage, open-field burning, heat-treatment (pasteurization), and other physical methods, usually to eliminate pests or separate them from the crop. Chemical control is the use of synthetic chemical pesticides to eliminate pests or reduce their effects. The many approaches to biological control can be categorized conceptionally into 1) regulation of the pest population (the classical approach), 2) exclusionary systems of protection (a living barrier of microorganisms on the plant or animal that deters infection or pest attack), and 3) systems of self-defense (resistance and immunization). The agents of biological control include the pest- or disease-agent itself (sterile males or avirulent strains of pathogens), antagonists or natural enemies, or the plant or animal managed or manipulated (immunized) to defend itself. The methods range from 1) conserving and making maximum use of indigenous (resident) biological control through cultural practices, 2) making one-time or occasional introductions of genes or natural enemies that are more or less self-sustaining and 3) making repeated introductions of a biocontrol agent (e.g. a microbial pesticide). Biological, physical, and chemical treatments and pest controls can be integrated into holistic plant-health care also known as integrated crop and pest management. Eight principles of plant health care are offered: 1) know the production limits of the agroecosystem; 2) rotate the crops; 3) maintain soil organic matter; 4) use clean planting material; 5) plant well-adapted, pest-resistant cultivars; 6) minimize environmental and nutritional stresses; 7) maximize the effects of beneficial organisms; and 8) protect with pesticides as necessary.

Biological control of arthropod pests has a long history of useful practical application. Parasites, predators, and pathogens have been employed in many cases to control pest arthropods in an efficient, cost-effective, and permanent manner. The traditional tactics used in biological control (classical, augmentation, and conservation) remain vital and valuable tools in the biological control of pests for agricultural crops, range lands, forests, and glasshouses. New technologies offer promise. One emerging technique involves the genetic improvement of natural enemies of arthropods through selection, hybridization, or recombinant DNA technology.

A shortage of effective, non-chemical pest control measures is a major constraint to more widespread adoption of sustainable agricultural practices. Overcoming this constraint with biological pest control tactics appears to be an attainable goal but will require substantial public sector support. Biological agents that are self-perpetuating do not offer profit incentive to private industry. On the other hand, microbial pesticides, which do require annual application, often are so highly specific for particular pests that the private sector is unable to risk venture capital for their development. Collaboration between public- and private-sector scientists is essential for biological pesticide development. In the U.S., a model working relationship for technology transfer between the private and public sector has been achieved with two commercial mycoherbicides, Collego™ and DeVine™. The model illustrates the strengths of the public sector for creating and storing fundamental knowledge of biological interactions at the organismal and ecosystem levels, also the capability of the private sector for large-scale production of fungi, for drying labile, living products, for effective patent protection, for satisfying EPA registration requirements, and for the commercial distribution, marketing and servicing of agricultural products. From three perspectives-biological, technical, and commercial—the success of Collego™ and DeVine™ has provided a definite step in the quest for low-cost weed control methods that are not hazardous to the environment nor in ground water. These successes also provide a model for an approach to reducing the dependence of agriculture upon chemical herbicides, the most extensively used chemical pesticides in agricultural production, likewise a useful insight toward technology that can lead to more widespread adoption of low-input, environmentally compatible and sustainable agricultural production.

CASST™ herbicide (Alternaria cassiae,) has been shown to be an effective biological control agent for sicklepod ("Cassia obtusifolia LJ, coffee senna ("Cassia occidentalis L.) and showy crotalaria ("Crotalaria spectabilis Roth). Current research has shown the potential of this mycoherbicide for use both alone and integrated with other herbicides as an effective commercial control measure for these troublesome weeds.

The U.S. public is expressing strong preference for the use of biological control methods in the management of U.S. agricultural, forest, and rangeland insect pests. This follows from a widespread understanding among citizens that synthetic insecticides have potentially harmful side effects on humans and that they are spreading increasingly as pollutants in the environment. Major recent increases in the number of pesticide-resistant insect species also put pressure on the agricultural community toward adoption of alternative non-agchemical plant and animal protection strategies. Movement in the direction of such alternatives has been facilitated by the fact that in the last two decades much progress has been made in Integrated Pest Management (IPM) through an improved understanding of the interactions of pests with their hosts. In that time period, many advances have been made in describing and predicting insect movement, seasonal cycles, and the effects of secondary plant compounds on insect reproduction. Simultaneously, much has been learned about the behavior, physiology, and population dynamics of insect parasitoids, i.e. parasites on insect pests. In the 1990's and subsequently, Biological Control Intensive Pest Management (BCIPM) will require continuing research to attain needed advancement in knowledge of growth and development of host plants, population dynamics of pests and parasitoids, and ecology of secondary pests that may interfere with implementation of BCIPM programs. Extension and research personnel will then be increasingly able to devise useful control methods for pests within selected cropping systems. We describe here examples to illustrate present and potential future use of BCIPM in different practical plant systems in New Jersey.

Serious side effects from the conventional use of traditional chemical pesticides for routine arthropod pest management have prompted the investigation and development of alternate strategies for the minimization of pest damage. Insect sex pheromones have been proposed as a potential group of alternative control agents for over twenty years. The possible uses of these substances for insect control are discussed and factors influencing their development for pest management are presented. The scientific research and commercial development of oriental fruit moth mating disruption is presented as a case study for the commercialization of this approach. Advantages and limitations of pheromone-based control tactics are presented. Mating disruption technology is starting to find its place in a number of diverse cropping situations. The use of pheromones for pest control promises to be an important component of the ongoing challenge to develop alternatives that may help to solve major environmental and human health problems associated with chemical pesticide use in agriculture.

Soilborne plant pathogens cause major economic losses in agricultural crops, and the present methods for control of diseases brought about by these pathogens are inadequate. Alternatives are also needed to substitute for the use of chemical fungicides. Many of these are known to induce tumors in experimental animals and are thus regarded by some investigators as potential human carcinogens when present as residues in food and water. In addition, such alternative control measures are needed because of the potential threat of development of resistance to fungicides, especially systemic fungicides, by fungal plant pathogens, and because of nontarget side effects on other plant pathogens and on beneficial microorganisms. Alternative disease control is sometimes possible through development of crop plants resistant to disease. Unfortunately, however, resistance is lacking or not available for many diseases caused by soilborne plant pathogens. Another biological means of controlling disease which is presently gaining much attention is biological control. Several systems of biological control are presently being explored and may be developed in a few years into reliable alternatives to conventional chemical control methods. The use of the mycoparasite Sporidesmium sclerotivorum, for example, against several diseases caused by Sclerotinia species is promising. Talaromyces flavus may in the future be exploited for use against several wilt diseases caused by Verticillium dahliae. Finally, practical control of several diseases caused by Pythium spp., Rhizoctonia solani, and Sclerotium rolfsii may eventually become possible through the use of Trichoderma spp. and Gliocladium virens. Development of these biological control systems will require much additional research directed toward a better understanding of the basic biology and mechanisms of action of beneficial fungi against plant pathogens. In addition, extensive cooperation will be required among research scientists, governmental agencies responsible for regulating the use of pestcontrol systems, and most importantly, private industry to develop biological control agents for the market and to coordinate acceptance and use by producers and acceptance by consumers.

The number of species of insect pests, estimated to be maximally 10,000 worldwide, forms only a small part of the millions of species of plant-eating insects. Chemical pest control is becoming increasingly difficult and objectionable in terms of environmental contamination so that other methods of pest control need to be developed. One of the best alternatives is biological control. Natural and inoculative biological control has already proven successful against a variety of pests over large areas. One is inclined to forget, however, how successful a biological control program has been as soon as the pest problem has been solved. Other types of biological control involving the regular introduction or augmentation of natural enemies are better known, although these have been applied on a much smaller scale; a survey of the present-day application of these latter types of biological control is presented here. Phases in the implementation of biological control are illustrated and needed future developments in research are discussed. The main limitation on the development of biological control is not the research, since natural enemies are easier found and with a much lower investment than new chemical pesticides, but rather the attitudes held by growers and disinterest on the part of industry, policy-makers, and politicians. The first priority for those concerned with the development and application of safer pest control should, therefore, be to change the perceptions that these other groups have of biological control.

Biological pest control techniques usually have identifiable costs and constraints that they must overcome before they will be adopted by farmers. Many biological control agents are developed in the public sector and need economic assessments at an early stage. The methods often have hidden costs related to farm labor adjustments or initial costs of development. Living biological controls frequently escape, and they may be disrupted by pesticides, regulations, or farm commodity programs. Pest control registration procedures and small markets also present obstacles. Area-wide implementation programs and changes in incentives for researchers may speed development and adoption of biological controls.

The extent to which pests should be managed by biological versus chemical methods has been a burning public policy issue since about 1950. A thorough policy analysis is needed to facilitate movement beyond the status quo. Such analysis should: a) review the extent of adoption of ecologically selective methods of pest control that have emerged from the last three decades of research, b) examine changes in policies, legislation and institutional arrangements that would foster more rapid and widespread adoption of environmentally benign pest controls, c) assess the role of biological controls in facilitating survival of farms during periods of economic adversity and in increasing the competitiveness of American agriculture, d) evaluate opportunities to use ecologically selective pest controls to improve water quality, to reduce environmental impacts of pests and of farming practices, and to preserve the usefulness of pest-resistant crop cultivars and pesticides, and e) identify options and mechanisms to further increase the flow of private and public resources into biocontrol research, development and implementation. A committee of highly accomplished and respected citizens needs to be formed to conduct a thorough analysis of the above and other issues related to the long-term economic viability of farming and to the development and widespread adoption of agricultural practices that will conserve and improve the resource base, and that are devoid of negative impacts on the environment and public health.

Traditional agricultural systems that have met the test of sustainability have not been able to respond adequately to modern rates of growth in demand for agricultural commodities. A meaningful definition of sustainability must include the enhancement of agricultural productivity. At present, the concept of sustainability is more adequate as a guide to research than to farming practice.