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CHAPTER 1 Introduction The objectives of insect-pest management and control are to create and main- tain situations in which insects are prevented from causing significant problems. These objectives may be achieved by preventing the establishment or spread of insect pests, by controlling established pest infestations, or by keeping infesta- tions at levels at which little or no damage or annoyance occurs. These should be accomplished at the lowest possible cost and without hazards to man or the desirable components of his environment. PURPOSE AND SCOPE The purpose of this book is to present the principles involved in various methods of insect-pest management and control in fields, forests, and urban and suburban communities. It was planned to interpolate recent attitudes and philosophies with the established principles and techniques that have served as the founda- tion for past pest-control programs. This approach includes an introduction to the ecological background underlying pest management, a discussion of the entire spectrum of control methodology, and the blending of these methods into dynamic systems of pest management. Principles, background knowledge, and guidelines are discussed to show the types of control that may be suitable for representative insect-pest problems. These are clarified with examples of pest control methods. The information is intended for use in selecting the most promising approaches in the development of effective pest management and control measures. The training needs and general organizational structure necessary to foster further progress in the refinement and application of this 1
2 INSECT-PEST MANAGEMENT AND CONTROL new philosophy of pest control are discussed. Attention is addressed to the economic rationale concerned with controlling pest infestations. While insect- pest control is the main topic, applications and practices of the control of other pest organisms customarily dealt with by entomologists are also discussed. Having presented discussions on well-established concepts and current hypothesis, the report points out areas where additional or new research is needed to modify, extend, develop, or perfect the present application of the principles involved. FACTORS IN INSECT-PEST PROBLEMS There are thousands of species of insect pests spread over most of the areas of the earth where poikilothermic animals can live. Each species of pest is limited to those accessible areas that provide it with food and other biological and physical essentials. It is estimated that in the United States 150 to 200 species or complexes of related species frequently cause serious damage. From time to time, 400 to 500 additional species are pests and may cause serious damage. Approximately another 6,000 species of insects are pests at times but seldom cause severe damage. Other countries throughout the world are infested with many insect pests. Migrations of insects may occur as a result of overcrowding, inadequate food, or weather unfavorable to further local increase, or when the insects reach a migratory state in their life cycle. Distances covered range from a few feet to many miles. Insects may attack several crops or only one. Expansion in world transportation has increased the likelihood of insect pests moving from one area to another. Much shorter transit times often favor the survival of pests. The problems in preventing the spread of insect pests are becoming more complex as a result of rapid changes in transportation. Some species of insects are pests throughout the year, others only at certain seasons. Insect pests may be active certain years and not others. Harvesting a crop may change the distribution of insect pests by forcing them to move to other crops that they would not normally infest. The factors affecting distribu- tion and activity are variable, so that the distribution of insect pests is con- stantly changing. In spite of this, the same insect pests often damage the same crop or crops in the same areas year after year. Variations in insect distribu- tion and activity are important factors for consideration in the development of economical and effective insect-pest management and control programs. The rate of reproduction of insects varies, but in general a great reproductive potential is characteristic of most species. The length of a generation differs. Death of adults before completion of egg-laying, and mortality of eggs, larvae,
INTRODUCTION 3 and pupae because of desiccation, starvation, parasites, predators, diseases, and other adverse factors, greatly reduces the number of insects produced under most environmental conditions. However, the high potential for reproduction of insect pests remains, and a population explosion of many species can be expected from a low-density level whenever suitable environmental conditions occur or control slackens. Insect pests have great adaptability and have adjusted to many ecological conditions and situations throughout the world. Not only have they become adapted to most opportunities for existence in the past, but they are continu- ing to adjust to changing man-made or natural ecological situations. An im- portant adaptation by insect and mite pests is the ability to develop resistance to pesticides. This is discussed in Chapter 16. Changes in cultural, agricultural, and economic patterns throughout the world have had a profound effect on insect-pest management and control. The realization that certain insects are carriers of organisms producing diseases in man has created insistent demands by the informed public that control methods be developed and used effectively to prevent the spread of such pests. The public also insists that control measures not have deleterious effects on man or the environment. There is a demand for control of mosqui- toes, flies, and other annoying insects in urban, suburban, and recreational areas. In dwellings, restaurants, hotels, motels, and certain other buildings, the presence of even an occasional insect may be considered undesirable. The change to continuous croppring systems over wide adjacent areas has created serious insect-pest management and control problems. The demand for agricultural products unblemished by insects has intensified the problems. Producers are subject to legal limitations on the amount of pesticide residue that is permissible on or in their products. Thus, they must balance legal requirements with consumers' demands. Agricultural and forest operations are highly competitive, and the margin of profit on many products is small even when maximum production is obtained. The small margin has greatly stimulated the demand for economic insect-pest controls. This subject is dis- cussed in Chapter 18. Certain pesticide residues may remain in the environment for years. More information is needed about food-chain concentration and practical ways of eliminating detrimental effects of pesticide residues that may remain in the environment after the pesticides have served their purpose. The pervasive nature of a few pesticide residues in the environment and in plants, animals, and man is justifiable cause for concern. This matter received the attention of the President's Science Advisory Committee in the United States, and its findings appear in the Report of the Environmental Pollution Panel issued in November 1965. The report discusses the value of pest control as well as the hazards of pesticide use.
INSECT-PEST MANAGEMENT AND CONTROL DAMAGE FROM INSECT PESTS Insects are pests when they reduce the quantity or quality of food, feed, forage, or fiber during production; damage commodities during harvesting, processing, marketing, storing, or use; transmit disease organisms to man or valuable plants or animals; injure or annoy useful animals or man; damage ornamental plants, lawns, or flowers; or damage homes and other personal property. During the production of most food, feed, and natural fibers essential to man, insects are continuously destroying a part of them. All types of crops, and other plants such as flowers, ornamentals, and lawn grasses, are damaged by insect pests attacking the roots, stems, leaves, and fruiting parts. Plant tissues are destroyed, and toxemias may occur. Both wild and domestic animals are annoyed and injured by insects and related pests. Insects also spread organisms that produce many serious plant and animal diseases. Insects cause widespread damage to agricultural and forest products during storage and distribution. Large amounts of stored grains are damaged both by actual consumption of the grain and by contamination with whole insects, insect fragments, and feces. The contamination of food by insects is a constant source of loss and concern. Insect fragments in packaged food are often inter- preted as indicating that the food has been processed under unsanitary condi- tions. Insects may occur in conspicuous numbers in food in sealed packages even though the food appeared free from infestation when packed. Termites can cause serious damage to wood used in buildings and to wood products. They are a constant threat in warm climates. Species of termites once confined to restricted areas of the world are now spreading into new territories. Such species increase the hazard of termite damage. Malaria is spread among humans by Anopheles mosquitoes carrying the causal organism; other human diseases result from insect-borne pathogens. Insects cause direct injury to man by their bites and stings and by contact. Salivary secretions injected during the feeding process may cause lingering irri- tation at the site of the bite. Some individuals show marked local reactions to certain insect bites. Also, an insect bite offers an opportunity for pathogenic organisms to penetrate the skin and cause serious infection. Some hymenop- terous insects, such as wasps and bees, inflict stings that cause pain and swelling. Allergic persons may die from a sting. Certain lepidopterous larvae have urticarial hairs that cause dermatitis when they contact the skin, and some of the blister beetles cause a blistering of the skin. The popularity of recreational areas is greatly diminished by the presence of chiggers, flies, mosquitoes, wasps, and other annoying pests. A human- disease epidemic spread by insect-borne pathogens, or the presence of
INTRODUCTION 5 numerous biting flies, in a resort area may cause widespread cancellation of reservations, resulting in heavy financial losses. Insect pests in the yard around a dwelling are very objectionable, and people go to considerable expense in an effort to control them. Although most insects do not harm man directly, some people have an illogical fear of them. This state of fear may be reduced when an individual learns more about insects, their habits, activities, and behavior. The presence of a few harmless insects may lead to excessive or unnecessary use of insecticides. In making estimates of losses from insect pests, it is very difficult to obtain information on any but major pests that repeatedly cause damage. The average annual loss from such insect pests and the cost of control in the United States during the period 1951-1960 is estimated at about $6.8 billion. Of this total, a loss of $6.1 billion was from crop, rangeland, turf, ornamental-plant, forest, forest-product, stored-product, livestock, and poultry insects, and from insect pests of honey bees. These figures do not include crop losses resulting from sporadic insect pests intermittently causing damage in an occasional year, which may be severe in a field, an area, or a region. A few estimates of average percentage losses from insects during production in 1951-1960 are: alfalfa for hay, 15%; corn, 12%; apples, 13%; cotton, 19%; oranges, 6%; rice, 4%; and soybeans, 3%. Estimates of loss during storage are 5.5% for corn and 3% for wheat. Average losses for a crop or commodity tend to hide the very high losses that may be suffered by individual producers or handlers. The average annual estimated cost of insect-pest control in the United States in 1951-1960 was $731 million. Economics of losses are dis- cussed in Chapter 18. When most of the people in the United States lived on farms, insect damage was taken for granted as part of the normal hazard of crop and animal pro- duction. However, with modern operations, the difference between a 5 and 10% loss can easily represent the difference between a profitable and an unprofitable farming operation. When faced with the prospect of a loss from insect damage, the modern producer needs to know whether the potential loss will be larger than the cost of control and approximately the difference. Better methods for determinating insect losses and more accurate estimations of probable insect damage in specific situations are needed. METHODS AND ECONOMICS Insect pests can be controlled by a variety of methods. The first principle in insect control is the correct identification of the pest. Identification of insects is discussed in Chapter 2. Correct identification provides a key to published
6 INSECT-PEST MANAGEMENT AND CONTROL information on the life history, behavior, ecology, and other factors important in the development of control measures for a pest. Once an insect pest has been correctly identified and the available information assembled, the appli- cability of various methods of pest management can be considered. In evalu- ating different methods of control for a particular pest, the harmless level of infestation, or the economic threshold, should be considered. The ecological factors affecting insect populations are of major importance in insect-pest control. All available knowledge about the biotic and abiotic characteristics of the environment affecting the pest should be used in weaving a pattern of insect control for a specific pest in a specific place. Figure 1 shows some of the components of the environment, the physiological status, and the process of development that affect growth, reproduction, and behavior of an insect. The manipulation of ecological or physiological factors by man may produce effective ways of controlling pests. (See Chapter 17 for a discussion FIGURE 1 Factors affecting insect activities. (From Agricultural Science Review 3:1, 1965.)
INTRODUCTION 7 of integrated control.) An understanding of the ecological factors affecting an insect-pest population is essential to planning or improving a control program. Adequate surveying or inspection of crops, animals, and products subject to insect damage is of primary importance in reducing the damage and the cost of control. This procedure permits detection of incipient or low-level infestations before they spread or develop to damaging proportions. Thorough inspections by trained personnel reveal whether control measures are actually needed and point out potential trouble spots or conditions especially favora- ble to insect-pest development, so that they can be eliminated or corrected. In planning the control of major insect pests, provisions must be made for obtaining adequate information on their activity and economic infestation levels (see Chapter 3). Research is usually needed to determine the best methods of obtaining and interpreting the required information. Successful insect-pest management and control are profitable. To deter- mine the possibility of making a profit from pest control, it is first desirable to determine the amount of pest damage. It is then possible to estimate what could be spent profitably in reducing the damage. The next step is to deter- mine the most efficient approach to the problem. All available methods of insect-pest management and control should be considered. These methods are discussed in detail in the following chapters. Good control must be economically sound for both immediate results and long-term effects. A control practice that builds up future problems should be avoided even though it gives excellent immediate results. A pesticide treat- ment that destroys the natural enemies of the pests that feed on a crop may allow the pests to multiply at a rapid rate after the lethal action of the pesticide has disappeared. It may also create a situation in which other pests, formerly held to low infestations by predators, parasites, or diseases, can increase at a rapid rate and become economically important. BIBLIOGRAPHY Allee, W. C., A. E. Emerson, O. Park, T. Park, and K. P. Schmidt. 1949. Principles of animal ecology. W. B. Saunders Co., Philadelphia. 837 pp. Andrewartha, H. G., and L. C. Birch. 1954. The distribution and abundance of animals. Univ. Chicago Press, Chicago. 782 pp. Cornwell, P. B. 1966. The entomology of radiation disinfestation of grain. Pergamon Press, Paris. 236 pp. Cotton, R. T. 1963. Pests of stored grain and grain products. 4th ed. Burgess Publishing Co., Minneapolis, Minn. 318 pp. Craighead, F. C. 1950. Insect enemies of eastern forests. U.S. Dept. Agr. Misc. Publ. 657. 679pp.
8 INSECT-PEST MANAGEMENT AND CONTROL Davidson, R. H., and L. M. Peaks. 1966. Insect pests of farm, garden and orchard. 6th ed. John Wiley & Sons, Inc., New York. 675 pp. Dowdeswell, W. H. 1961. Animal ecology. Harper & Brothers, New York. 209pp. Ebeling, Walter. 1959. Subtropical fruit pests. Univ. California, Div. Agr. Sci., Berkeley. 436 pp. Herms, W. B., and M. T. James. 1961. Medical entomology. 5th ed. Macmillan Co., New York. 616 pp. Jones, F. G. W., and M. G. Jones. 1964. Pests of field crops. St. Martin's Press, Inc., New York. 406 pp. Keen, F. P. 1952. Insect enemies of western forests. U.S. Dept. Agr. Misc. Publ. 273. 280 pp. Kurtz, O. L., and R. L. Harris. Circa 1962. Micro-analytical entomology for food sanita- tion control. Ass. Offic. Agr. Chem., Washington, D. C. 576 pp. Mallis, A. 1960. Handbook of pest control. McNair-Dorland Co., New York. 1132pp. Metcalf, C. L., and W. P. Flint. 1962. Destructive and useful insects: Their habits and control. 4th ed. (Revised by R. L. Metcalf). McGraw-Hill Book Co., Inc., New York. 1087 pp. Newcomer, E. J. 1966. Insect pests of deciduous fruits in the West. U.S. Dep. Agr. Handb. 306. 57 pp. Pfadt, R. E., Editor. 1962. Fundamentals of applied entomology. Macmillan Co., New York. 668 pp. Ross, H. H. 1965. A textbook of entomology. 3rd ed. John Wiley & Sons, Inc., New York. 539pp. Truman, L. C., and W. L. Butts. 1967. Scientific guide to pest control technology. 2nd ed. Pest Control Magazine, Cleveland, Ohio. 187 pp. United States Department of Agriculture. 1952. Insects. U.S. Dept. Agr. yearb. 780pp. United States Department of Agriculture, Agricultural Research Service. 1965. Losses in agriculture. U.S. Dep. Agr. Handb. 291. 120pp. United States Department of Agriculture, Agricultural Research Service, Plant Pest Control Division, Survey and Detection Operations. Cooperative economic insect report. Hyattsville, Md. (Published weekly). Uvarov, B. P. 1931. Insects and climate. Trans. Entomol. Soc. London LXXIX (I): 1-247. Whitten, J. L. 1966. That we may live. D. Van Nostrand Co., Princeton, N. J. 251 pp.