This brief history traces the interactions of humans and insects dating from the adoption of agriculture some 10,000 years ago and its inherent ecological disruptions. Humankind’s early preoccupation with survival focused on insects as relentless pests, competitors for food and fiber, threats to health and comfort. The high hopes following World War II for relief from the bondage of insects through the use of chemical insecticides such as DDT proved unrealistic. The reassessment that followed led to a concept, based on ecological principles, that is referred to as integrated pest management (IPM). In this system, multiple control technologies are used, with the additive effect being to hold insect injury at acceptable levels, while avoiding excessive environmental insult. The age-old struggle continues; entomologists are now armed with the lessons of the past and aided by advances in insecticidal chemistry, biological and cultural control, and visionary new technologies based on genetic modification of plants and animals. Entomologists are also facing new challenges from invasive species brought on by the increased international movement of people and goods in the global economy,and by global warming, which threatens to dramatically alter the geographic ranges of plant and animal species, including agricultural crops and their pests, as well as vectors of human and animal pathogens. Simultaneously, the rise of the environmental movement and ecological awareness has placed insects in a new context, highlighting their essential role in biodiversity on which the viability of the earth depends. The vision for the 21st century calls for compatibility between insect control and conservation; both are prerequisites to human well-being. Stewardship of the earth is the greatest challenge ahead and one that places awesome responsibility on the shoulders of entomologists.
IN THE BEGINNING
The history of life on earth reaches back some 4 billion years. From this beginning, the long evolutionary trail unwound. Along the way, 99% of the forms that appeared met with extinction.
The great exterminations that have occurred since the appearance of insects in the Devonian period, 400mya, have revealed insects’ remarkable survival qualities. Insects witnessed the last of the trilo-bites that preceded them by 175 million years. By the time dinosaurs appeared in the Triassic period, 210 mya, the major orders of insects existing today were well established. Dinosaurs became extinct 66 mya, leaving a niche occupied in time by mammals. The mammals, in turn, provided a niche for insects, offering furry cover and warm meals. The disappearance of the dinosaurs coincided with a great radiation of insects based on insects’ symbiosis with flowering plants. For the past 150 million years, the flowering plants and insects have honed their intricate coevolution, which accounts for their immense biodiversity on which human habitability of the earth depends.
Insects have withstood trial by ice and fire, meteorite strikes, volcanic eruptions, global dust veils, acid rain, and continental upheavals. This evolutionary experience is encoded in their DNA and attests to the advantage of their small size, external skeleton, flight, metamorphosis, and specialized systems of reproduction. These are significant credentials in insects’ rivalry with Homo sapiens, a species that draws on an evolutionary history of a scant 7 million years.
COEXISTENCE, HUMANS AND INSECTS
The class Insecta has plagued and fascinated humans for all of their history. The most striking features of the Insecta are diversity and numerical superiority. Of the 5-30 million species estimated to compose the global flora and fauna, approximately 1.7 million have been named, and more than half are insects. It is estimated that insects make up 75% of the known animal kingdom.
Because insects occupy almost every conceivable terrestrial niche, they interact with humans in countless ways that accord them status as “pests.” This same diversity bestows on insects essential roles in the functioning of the biosphere as a sustainable biological system. Considering the countless interactions between humans and insects, it is not surprising that insects have become fixed in the fabric of human culture. They have become important components of our art, language, literature, music, philosophy, and religion. In addition, insects are remarkable sources of knowledge, ideal models for the study of biological processes, including genetics, physiology, and molecular biology.
Professional entomologists find challenge in our universities, where they engage in teaching, in research to advance knowledge, and in extension, applying knowledge to the solution of applied entomological problems. In addition to professional entomologists, amateur naturalists are drawn to the study of insects because of their form, color, and behavior. As the expanding human population continues its modification of the natural habitat, the interface between humans and insects will become more problematic.
ENTOMOLOGICAL ROOTS
A mere 10,000 years ago, primitive hunter-gatherers made a great leap forward; they entered into partnership with plants, and thus agriculture was born. Thereafter, humans would seek to alter ecosystems to their advantage. They would intervene to favor some plants and animals over others, thereby altering the evolutionary process that had shaped the biological world for the preceding 4 billion years.
Insects in their coevolution with plants and animals had been a powerful force in shaping the biosphere. They posed a primary threat to humans’ alteration of ecosystems to provide food, fiber, shelter, and comfort for themselves and their domestic animals. The struggle that followed moved through stages of ignorance, myth, religion, and then enlightenment through science and technology.
Our brief historical sweep will jump the seemingly long sleep of ancient civilizations and go to the Greek civilization in the time of Aristotle (384-322 B.C.). The orderly study of biology began with his speculations. He relied on his own observations, defined the field, posed questions, and accumulated evidence to answer them. Aristotle’s vision of rationality lay dormant for centuries until the Renaissance. In the meantime, Judaism and Christianity imposed a new concept, one focused on God and creation as depicted in the topic of Genesis. Accordingly, God created the world, directing man to “be fruitful and multiply…” and “with domination over every living thing that moves upon the earth” (Genesis 1:28). Man was not part of nature. Nature was subservient to man.
The scientific revolution of the 16th and 17th centuries marked the beginning of modern science and included mathematics, mechanics, and astronomy but had little impact on biology. While the revolution rejected superstition, magic, and the dogma of medieval theologians, it did not reject the ideological bias of the Judeo-Christian religion. The hand of God was still directing the course of the natural world.
Not until the 17th and 18th centuries was entomology advanced as a field of study within zoology. Anton van Leeuwenhoek (1632-1723) used the microscope to extend the power of the human eye. He was obsessed with the study of detail, including the morphology and specialized organs of insects. His revelations established insects as proper subjects for scientific study. Francesco Redi (1626-1697) demonstrated in 1668 that insects arose not from spontaneous generation but from eggs laid by fertilized females. Jan Swammerdam (1637- 1680) did superb anatomical work on insects, including the honey bee.
The excitement of these discoveries was further enhanced by the flow of exotic plants and animals brought back from voyages on other continents. Charles Darwin’s voyage of HMS Beagle in 18311836 followed this tradition. The wealth of material acquired made students aware of the need to classify the organisms collected and to assemble specimens in orderly collections. Other investigators focused on the activity of insects in the field and their role as pollinators and as agricultural pests.
A prerequisite to advancing the study of insects was the development of a classification system that would bring order out of chaos. The Swedish naturalist Carl Linnaeus (1707-1778) met this need. Although trained in medicine, he studied botany extensively and turned to the classification of plants, animals, and minerals. His Systema Naturae (10th Ed., 1758) is the foundation stone of zoological nomenclature.
He greatly simplified insect classification by using insect wings (hence the suffix -ptera, meaning wing, for most order names) as the basis for classification. The other great feature of his system was the designation of genus and species each by a single word, thus providing a binomial system to replace the unwieldy descriptive names employed earlier. Linnaeus’s “artificial” system of insect systematics based only on wings was in time modified by adding other characters to construct a “natural” system.
Another great naturalist, Rene Antoine Ferchault de Reaumur (1683-1757), infused a new perspective into the emerging study of insects. He deplored the confusion that existed regarding metamorphosis, distribution, and “industries” of insects. He championed the study of insects out of sheer curiosity, claiming that useful discoveries would be made in the process. His six volumes of Memoires pour Servir a l’Histoire des Insectes (1734-1742) with their exacting attention to morphology and function, complete with accurate drawings, established a new standard of excellence.
The work of Linnaeus and Reaumur provided the templates for orderly classification and elucidation of fundamental and applied aspects of entomology. Their works were extended and refined by French naturalists Pierre Andre Latreille (1762-1833), Georges
Cuvier (1769-1832), and Jean Lamarck (1744-1829). By the 19th
century, entomology was firmly established in European zoological science. The taxonomic treaties established in this process were to provide guides for the classification of American insects. These sources were augmented by two sources in Great Britain, Gilbert White’s (1720-1793) The Natural History and Antiquities ofSelborne (1789) and William Kirby (1759-1850) and William Spence’s (1783-1860) Introduction to Entomology (1816-1826). The writings of these field naturalists on the biological characteristics of insects made insects, at one point, the most popular components of natural history in Victorian England. In addition, they contributed to the development of the concept of the biological species. This concept, essential to the understanding of biological communities, recognizes a species as a reproductively (genetically) isolated group of interbreeding populations.
The next step in the unfolding of the biological sciences was a great one: the publication in 1859 of Charles Darwin’s (1809-1882) theory, On the Origin of Species. This event placed conceptual biology in a new light. In a single stroke, Darwin’s work challenged the natural theology that had dominated biological thought for three centuries. Natural theology had been elaborated in John Ray’s (1627-1705) The Wisdom of God Manifested in the Works of the Creation, published in 1691. The concept provided a truce between science and religion. It contended that God created the world and the evidence of His omnipotence was to be found in the study of His creatures.
There was no middle ground between Darwin and Ray. Darwin provided a new way of viewing biology. The living world had evolved; it could be explained on the basis of descent with change. It was noteworthy to entomologists that much of Darwin’s supporting evidence was derived from his study of insects dating from his days at Cambridge University (1828), where he was an avid insect collector.
Intense debate followed the publication of Darwin’s theory. Nowhere was the debate more intense than at Harvard University, where Asa Gray (1810-1888), a botanist and staunch Darwinian, challenged Louis Agassiz (1807-1875), the foremost naturalist of the world and unrelenting defender of the creationist view.
An unlikely pair of outspoken individuals led the pro-Darwinian entomologists of North America. Benjamin D. Walsh (1801-1869), who had collected beetles with Darwin at Cambridge University, emerged from obscurity on the Illinois frontier to assert his long-dormant entomological interest and declare his support for Darwinism. He was joined by the youthful Charles V. Riley (1843-1895), a fellow Englishman and self-taught entomologist who was then writing on entomology for the Prairie Farmer, the leading farm journal of the Midwest (Fig. 1). Their early collaboration on the issue of Darwinism bode well for the future. In time, evolution was accepted by biologists as a fundamental basis of the discipline, although segments of the public still oppose it as a challenge to the Creation story as reported in the Old Testament topic of Genesis. The distinguished geneticist Theodosius Dobzhansky (1900-1975) summarized his views on the major fields of biology in his essay entitled “Nothing in Biology Makes Sense Except in the Light of Evolution” (1973).
ENTOMOLOGY IN THE NEW WORLD
Nurturing Environment and Supporting Institutions
EMPIRE AND INSECTS
Early entomological developments in the United States occurred in the climate of Thomas Jefferson’s America. Jefferson took office as the nation’s third president in March 1801 and proceeded to sell his vision to his countrymen, then numbering just over 5 million. The United States had only recently gained its independence from England. Louisiana, stretching from the Mississippi to the Pacific Ocean, although claimed by Spain, was available and being considered by Russia, France, and England. Of these three, France, energized by Napoleon, was feared the most. Despite the tenuousness of the situation, Jefferson clung to his
vision of this vast landmass, stretching from sea to sea, being united under a stable government of the United States. Napoleon’s agreement to sell Louisiana came as a surprise; its purchase, although not applauded by some leading politicians, was a masterful stroke. It doubled the landmass of the United States and resolved the feud over the control of the Mississippi River. But what had been purchased? To answer that question, Jefferson dispatched an expedition led by Captain Meriweather Lewis and Lieutenant William Clark (1804-1805) to explore the new acquisition. Their report, on their return, removed some of the mystique of the Pacific Northwest but provided only tantalizing glimpses of the area’s natural history. Unfortunately, the expedition included no trained naturalists.
The follow-up to Lewis and Clark’s report came in 1819-1820. Major Stephen H. Long, under authorization of President Monroe, led an expedition of “Gentlemen of Science” to study this vast unexplored territory, its natural history, and the American Indians of the Rocky Mountain region. Entomology was well represented by Thomas Say, whose affiliation with the Academy of Natural Sciences of Philadelphia had won him the reputation as “perhaps the most brilliant zoologist in the country.” Say epitomized the confidence and vision of the young nation’s leaders in natural history.
Although Say’s primary interest was insects, he covered the entire field of botany and zoology and conducted studies on the American Indians. His entomological studies provided the foundation for his American Entomology, published in three volumes (1824, 1825, and 1828). These were the first topic on North American insects. They were beautifully illustrated by the artistic talents of his wife Lucy and Titian Peale of the distinguished family of Philadelphia artists. They provided a stimulus for American entomologists and signaled their emancipation from the European centers to which the study of American insects had previously been consigned, named by Europeans, and retained in their collections. With the spirit of the revolution still vibrant, consigning American insects to European collections offended national pride.
The Long Expedition imparted an American quality to the study of the nation’s natural history. The gentlemen of science who manned the expedition were trained in the nation’s centers of learning. They were not closet naturalists; they were adventurers. Their spirit was described by Say himself: “If our utmost exertions can perform only a part of a projected task, they may, at the same time, claim the praise due to the adventurous pioneer for removing the difficulties in favor of our successors” (American Entomology).
THE CULTURAL CENTERS
Natural history found strong support in the cultural centers of Philadelphia, Boston, and New York. Philadelphia led the way, with the American Philosophical Society and the influence of the distinguished Benjamin Franklin (1706-1790). The Academy of Natural Sciences, founded in 1812, nurtured the founding of the Entomological Society of Philadelphia in 1859, which in turn launched the Practical Entomologist in 1865.
Boston looked to Harvard College and the Massachusetts Society for Promoting Agriculture. William D. Peck (1763-1822) was appointed professor of natural history at Harvard in 1805 and offered the first lectures in entomology in North America. Thaddeus William Harris (1795-1853), a physician turned Harvard librarian, found time to become entomological author, teacher, collector, and correspondent. His report on A Treatise on Some of the Insects Injurious to Vegetation (1841) summarized the knowledge of insect control in Europe and North America, earning him the title ” Father of Economic Entomology.”
New York asserted its interest by appointing Amos Eaton and John E. LeConte to the Lyceum of Natural History of New York. Other distinguished leaders included John Abbot (1751-1840), Thomas Say
(1787-1834), and Frederick V. Melsheimer (1749-1814). A striking feature of these men and their institutions was their support for both classical and applied entomology. The individuals were well trained by the standards of the day, often completing training in medicine or theology, because there was no specific training in entomology.
Systematics was the primary entomology interest, followed by aid to agriculture, which was beset with countless insect pests. These leaders experienced the frustration of gaining access to the European literature, founding periodicals for the publications of their own findings, and establishing reference collections.
In the 1840s, American entomologists turned to the task of establishing institutions that would sever their European dependence. The institutional framework took shape rapidly, led by the American Association for the Advancement of Science (AAAS), founded in 1847. It marked a transition from amateur to professional status, provided a national scientific forum, and nurtured the founding of professional societies. Within approximately 2 decades, 1859- 1881, five additional societies were established in North America: the Entomological Society of Philadelphia (1859), The Entomological Society of Canada (1862), and the Entomological Club of the AAAS (1872). The institutional framework was now in place to expand the scientific and technical dimensions of entomology.
STATE AND FEDERAL ACTION IN THE UNITED
STATES Agriculture held the key to moving the nation from an agrarian to an industrial society. The farmer was viewed as the noblest and most independent man in society. Unlike in Europe, the availability of fertile soil was seemingly unlimited. While great physical obstacles lay in the path of progress, limits of the human intellect posed the greatest obstacle. With these elements in the national outlook, it followed that state and federal action would augment the private efforts in support of agriculture and entomology. In 1854, two landmark appointments were made: Townsend Glover was appointed to the Federal Patent Office for work in the newly established Bureau of Entomology, and New York State, responding to pressure from the New York State Agricultural Society, appointed Asa Fitch as its first state entomologist. Illinois and Missouri followed suit in 1868 with the appointments of Benjamin D. Walsh and Charles V. Riley.
These appointments represented historic landmarks, because state and federal funds were appropriated in support of agriculture with entomology in the vanguard. These men were able individuals whose evangelical zeal and sound professional grounding were attuned to national goals. Their publications, with Charles V Riley’s nine Missouri reports forming the core, laid the foundation for applied entomology in North America.
National goals for agriculture led to enabling federal legislation in three steps. The Morrill Land-Grant Act of 1862 provided grants to each state, the proceeds from which funded a college, “to teach such branches of learning as are related to agriculture and the mechanical arts….” In 1887 the Hatch Act added a research dimension by establishing in each college state experiment stations coordinated by a central office in the Department of Agriculture in Washington, DC. The foregoing events, occurring within approximately 3 decades, provided an impetus for applied entomology that was unprecedented in the world. Cooperative Extension, the outreach arm of the Land-Grant University, which had been active from the start, was formally recognized and funded by the Smith-Lever Act of 1914. This institutional framework with its catalytic feedback from teaching, research, and extension has been recognized as one of the greatest educational innovations of all time.
With economic entomology rapidly expanding under the stimulus of experiment stations, Charles V. Riley, then chief of the Bureau of Entomology, perceived the need for a national organization to advance the goals of economic entomology. His organizational abilities and partnership with his Canadian counterpart, James Fletcher, led to the establishment of the American Association of Economic Entomologists in 1889. At Riley’s insistence, the association focused on economic entomology, leaving unmet the needs of the broader dimensions of biology, taxonomy, morphology, and faunistic studies of insects. In 1906, the Entomological Society of America was organized to meet those needs, with John Henry Comstock of Cornell University serving as president. With the various forces that shaped these professional and governmental institutions in mind, we can examine how the institutions responded to the challenge posed by insect pests.
Insect Pests
That the world is not awash in insects, despite their remarkable potential for reproduction, attests to the “balance of nature.” But nature’s balance, while avoiding extremes, does not preclude insect activity that is annoying to humans. Insects that take human’s crops or blood, and invade their dwellings, are termed “pests.” The term has no biological significance; it only expresses a human perception.
Let us examine a few insect outbreaks that occurred in agricultural, medical, and veterinary entomology in the late 1800s. They were to test the mettle of the institutions crafted to address such problems. They taught us much about insects, ourselves, and our vast landmass with its unique biomes and punctuated with its geographical features: the Rockies in the west, the Appalachian range in the east, the Great Plains, the Great Lakes, and the Mississippi. It was this abundance of land that appealed to the early settlers from land-poor Europe. It was from the vastness of the land with its rich flora and fauna, coupled with the democratic spirit of its people, that the American dream was fashioned. However, the dream’s social fabric was not matched by its concept of stewardship of the land. New England’s forest primeval had to be breached to make way for agriculture. Conquering nature was viewed as a prelude to progress, and the American Indians and the bison fared poorly under this credo.
AGRICULTURAL ENTOMOLOGY
The Colorado potato beetle, Leptinotarsa decemlineata, existed in the foothills of the Rockies on the buffalo bur, Solanum rostratum. As pioneer settlers pushed westward with their crops, the beetle colonized the cultivated potato, Solanum tuberosum. and began its eastern migration along the “potato trail.” It was observed as a potato pest in Nebraska in 1859, reached the Atlantic coast by 1874, and traveled thence to Europe in 1876, where it remains an important pest.
The early search for control measures established the arsenical Paris green, an industrial pigment, as an effective poison. It soon became the standard treatment and was the first widely used poison to kill by ingestion.
The early marketing of insecticides invited fraud through adulteration and false claims. It was not until 1910 that a federal legislation was passed, requiring labeling to reveal the efficacy of and the ingredients in the two most widely used insecticides, Paris green and lead arsenate.
The boll weevil, Anthonomous grandis, crossed the Rio Grande to Texas in 1894 and began its eastward trek, occupying the entire 1,500,000 km2 cotton belt by 1925. Efforts to impede its progress by establishing no-cotton barriers failed for lack of community compliance. Countless control measures were tried, but insecticides eventually won as the first line of defense. Calcium arsenate was adopted for control in about 1920, and its use soon reached 20,000 tons per year. This marked a new scale of area-wide pesticide treatment with its attendant environmental and human safety problems.
The social and economic impact of the weevil was incalculable. The prosperity of the South evolved around a single crop, cotton. With its loss, the economic infrastructure collapsed, and panic ensued. Black laborers left, mortgages were foreclosed, and banks failed. The potential for economic disaster in the wake of insect outbreak was seared in the memory of the people of the cotton-producing states. Only the Civil War had greater impact on the economic and social life of the southern states than did the boll weevil.
The Rocky Mountain grasshopper, Melanoplus spertus, appeared in an epidemic eastward migration, borne on wind currents from the foothills of the Rockies to the Mississippi valley in 1874-1876. Presumably, this migration was in response to the agricultural disruption of the ecosystem that had been dominated by the American bison. The ravages of these hordes of airborne insects created a crisis for the affected states, whose governors appealed to Washington, DC, for federal intervention. In response, the U.S. Entomological Commission was created with the colorful Charles V. Riley as its chairman. This was not a staid Washington bureaucracy; it was a mobile force that reached out to the crisis whenever it arose. Riley scoffed at Sundays devoted to prayer for divine intervention to restrain the pest. Rather, he urged the people to adopt control measures based on intricate knowledge of the life history of the pest. His insights led to bold predictions of the pest’s demise from natural causes. With some sound observations and a modicum of luck, his predictions held. The commission, despite its denials, was credited with solving the problem, bringing new credibility to entomologists and federal aid to the states.
The gypsy moth, Lymantria dispar, was introduced from France, not by accident but by design, by Leopold Trouvelot (1827- 1895), a Harvard astronomer and amateur entomologist who was interested in silk-producing moths. Larvae emerging from egg masses he had imported escaped from his Medford, Massachusetts, residence in 1869. After a period of 20 years, the moth reappeared in an epidemic outbreak, after having been mistakenly overlooked as a native species. With this head start, the scorched earth practice of cutting and burning infested trees, augmented by arsenical sprays, failed. The effort did stimulate advances in the technology of spray machines. Today this introduced pest has spread westward and southward, occupying a swath from the Great Lakes to the Carolinas.
Biological control was enthusiastically touted, following the spectacular success achieved by Charles V. Riley’s innovative introduction of the vedalia beetle, Rodolia cardinalis (Coleoptera), into California to destroy the cottony cushion scale, Icerya purchasi. The pest had been introduced from Australia about 1868 and soon threatened destruction of the state’s citrus industry. Two years after the introduction of the predator, the pest was miraculously under control.
The whole array of control measures, cultural, mechanical, chemical, plant resistance, and biological, was employed, seeking to cope with these problems. The entomologists were influenced by expectations and perspectives of their farmer clientele. The farmer’s time frame was established based on the harvest date and sale of the crop; the farmer’s risk tolerance was low. Insecticides provided immediate and predictable results and became the backbone of control programs.
Meanwhile, several factors intensified the pressure for insect control, including monoculture, susceptible crops, exacting market standards, and introduced pests; all required greater interventions and modification of the agroecosystem.
MEDICAL AND VETERINARY ENTOMOLOGY
The foundation for modern medical and veterinary entomology was laid by Louis Pasteur, a French microbiologist who formulated the theory of microbial causation of disease, based on his work with the silkworm, Bombyx mori. in 1887. Without benefit of the germ theory, Josiah Nott, a Mobile, Alabama, physician, proposed (1848) that the causative agents of malaria and yellow fever were transmitted by mosquitoes. In 1881, Carlos Finlay, a Cuban physician, postulated that mosquitoes transmitted the yellow fever agent, setting the stage for Major Walter Reed and associates to verify his claim. In 1897, Ronald Ross demonstrated the occurrence of the malaria parasite in mosquitoes that fed on a human patient whose blood contained the parasite, thus leading to the elucidation of the epidemiology of malaria.
In 1889, Theobold Smith discovered the causative agent of Texas cattle fever and, working with F. I. Kilbowen, showed in 1893 that the cattle tick, Boophilus annulatus, was the vector. Their work paved the way for tick prevention and development of the cattle industry in the southern United States.
These experiences in control of insects of agricultural, medical, and veterinary importance were unprecedented in the American experience and left no region untouched. They revealed the social, political, biological, economic, and environmental dimensions of insect problems. A nation leaning so heavily on agriculture was sensitive to the impact of these problems on its well-being.
The fundamental principles gleaned from these experiences were to shape the philosophy of insect control for the future. They included the following: (1) Taxonomic knowledge of the vast insect fauna is a prerequisite for detection and development of control programs; (2) advances in international commerce breach the ancient oceanic barriers to the dispersal of insects and increase the likelihood of introducing exotic species; (3) introduced species, uninhibited by their natural controls, often become major pests in their new habitat; (4) the economic well-being of vast regions of the nation is vulnerable to insect attack; (5) intervention at the federal level is required for insect problems beyond the scope of individual states; (6) alterations of ecosystems trigger changes in patterns of insect behavior; (7) the use of insecticides requires federal regulations to protect the user, the public, and the environment; and (8) an informed public will underwrite sound programs of insect control.
PARTNERSHIP IN PEST CONTROL,
1880 TO WORLD WAR I
The institutional framework for colleges of agriculture was well established by 1880. The first department of entomology was founded at Cornell University in 1874 under the leadership of John Henry Comstock; others followed shortly. The primary objective of the department was to train students who wished to become farmers, to identify and classify the insect fauna, to study life cycles, to devise control measures, and to train farmers in their use.
As insecticides became a more important component of production technology, an alliance of increasing importance developed among the agricultural constituency, the agricultural colleges, and the chemical industry. As this partnership developed, agribusiness expanded to provide the goods and services required for agricultural production and became even more mechanized, technical, and capital intensive. The three partners shared a common objective, pooling their resources to increase the efficiency of agricultural production that accrued ultimately to the benefit of the consumer.
The arrangement involved the agricultural constituency, lending political support to the agricultural colleges, in return, for their services. The colleges then aided the chemical industry by testing their products and giving their approval, which enhanced their marketability. A grateful chemical industry provided grants to the entomology departments, which were always short of operational funds. The deans at the agricultural colleges had the difficult task of being a broker between the college faculty leaning toward basic research and the farm constituency seeking low-risk pest control programs. The arrangement was an American innovation that seemed to please everyone. Furthermore, the chemical industry was greatly stimulated by the economic and political activities of World War I. Food and fiber production was given high priority, and new discoveries advanced the pesticide industry.
The period from 1880 to 1940 witnessed the maturing of the Agricultural Experiment Stations as a national, highly coordinated network. The extension entomologists became the connecting link between the agricultural college and the agricultural producer. Because insecticides had become the first line of defense, the growing chemical industry added strength to this already-solid partnership with the colleges and farmers in the aftermath of World War II. Furthermore, this was the threshold of an era of discovery of new molecules that would affect biological processes of plants and animals.
Along the way, some ominous straws in the wind signaled trouble ahead. In 1913, the San Jose scale, Quadraspidiotus perniciosus, developed resistance to lime sulfur, but the phenomenon was not recognized as an expression of Darwinian selection. In 1928, the codling moth, Cydia pomonella, was shown to be resistant to lead arsenate. The apple industry was dealt a severe blow in the mid-1930s when British markets rejected fruit from the United States because of high arsenical residues. Simultaneously, fruit trees were showing loss of vigor because of insecticidal toxicity to foliage and accumulation of residues in the soil.
Although these disquieting revelations were not widely publicized, they were of concern to entomologists, as they and the pesticide industry were marshaled to meet the greater demands for food and fiber required for World War II. Even then, the sustainability of insecticidal control was clearly in doubt.
ENTOMOLOGY, POST-WORLD WAR II
Technology’s Triumph
The explosion of the atom bomb over Nagasaki in 1945 brought a dramatic end to World War II and, in so doing, highlighted the role of science and technology in the victory. Following this, the age-old ritual of “beating swords into plowshares” turned scientific and technical advances to peaceful ends. No field emerged with more exciting prospects than did the field of entomology. DDT, with its wartime secrecy removed, was hailed as the answer to insect control. Its use in arresting an epidemic of typhus in Naples in 1943-1944 dramatically neutralized the lethal companion of armed conflict, vector-borne disease.
Overnight, the entomological community documented DDT’s remarkable effectiveness in controlling insect pests of agricultural, medical, and veterinary importance. The race was on, and an old alliance assumed new vigor. The Land Grant Universities joined with industry and agriculture to exploit the new possibilities of chemical pest control.
Although industrial grants to the Agricultural Experiment Stations to fund trials of mutual interest dated from the early 1930s, they assumed a greater role in experiment station research as the partnership geared up for a new era in the synthesis of pesticides. The chlorinated hydrocarbons, with DDT as their prototype, yielded related compounds, followed by the development of organophos-phates, methyl carbamates, and pyrethroids—all neuroactive compounds. By the 1950s, post-World War II insecticides had become the mainstay of insect control, with the prewar calls for biological and cultural controls in eclipse.
Enter Rachel Carson
Early warnings of the danger of insecticide mania were sounded within the entomological community, but these warnings were largely ignored. It was the publication by Rachel Carson (Fig. 2 ) of Silent Spring in 1962 that triggered the avalanche of public concern. She lamented that “so primitive a science has armed itself with the most modern and terrible weapons” and that “i n turning them against the insect, it has turned them against the earth.”
FIGURE 2 Rachel Carson’s Silent Spring (1962) focused public attention on the pesticide issue. Her crusade catalyzed the environmental movement.
Overnight, her exhortation changed the public’s perception of entomologists. Their traditional obscurity was swept away. They were in the public eye, viewed as allies with the corporate giants, poisoners of robins and the earth, all under the pious veil of aiding the consumer by adding the farmer.
Response to Rachel Carson’s charges came largely from industry, whose strategy was to discount the witness. This proved ineffective as accumulating evidence reinforced her concerns. Practices that endangered birds, especially the national symbol, the American eagle, were certain to stir emotions.
Carson’s Silent Spring became a cornerstone of the environmental movement. Her thesis focused on the “web of life,” which placed humanity’s relationship to all forms of life in an ecological context.
Concern for the environment and the natural world triggered by Silent Spring melded with other concerns for humans—women’s rights, the war in Vietnam, and Native American rights—to give rise to the broadly based environmental movement embracing the rights of humans and nature, animate and inanimate. This great philosophical debate extending over the past 4 decades proceeded without the active involvement of the entomological community.
One of the immediate effects of Silent Spring was to make pesticide policy a matter of public debate. While focusing on DDT, the issue became broader and embraced the central tenet of the environmental movement that human intervention had become the dominant environmental influence on the planet. The fact that DDT residues could be found in Antarctica incorporated entomologists in the global insult.
In 1967, a group of concerned individuals formed the Environmental Defense Fund to use litigation in defense of citizens’ rights to a clean environment. In protracted public hearings, entomologists were called to testify that their practices were not infringing on citizens’ rights to a clean environment. It was an uncomfortable defensive position in which these dedicated “defenders of agriculture” were placed.
In 1972, a decade after Silent Spring, the Environmental Protection Agency banned DDT. Its meteoric rise and fall, from discovery to banning, had spanned only 3 decades.
Economic entomologists in general viewed Silent Spring as an attack on their professional competence and integrity. Since the late 19th century, they had cultivated a self-image as dedicated public servants, bringing science “io the distressed husbandman” whose labors were closely aligned with the national interest. This explains in part their emotional response and the sense of hurt that has lingered among entomologists of the DDT era.
Ecology’s Promise
Economic entomologists of the 1960s faced two daunting challenges: the loss of public confidence in the aftermath of Silent Spring and the failure of their programs of insect control. These were powerful incentives for reassessment.
In the early 1950s, well before Silent Spring, the concerns regarding the insecticidal treadmill led a group of entomologists at the University of California at Berkeley and at Riverside to reassess control practices. Drawing on the biological control heritage pioneered by Harry Scott Smith (1883-1957), they sought to “integrate” features of biological control and chemical control. This concept, with further refinement, led to the adoption of IPM by the late 1960s. In practice, IPM seeks to integrate multiple control measures into a cohesive package, the additive impact of which would hold pests within acceptable levels while taking into account economic, environmental, and social costs and benefits. The abbreviation “IPM” was soon adopted worldwide to identify a holistic approach to pest control. Its enthusiastic reception reflected that optimism accorded a new paradigm, one that placed pest control on an ecological foundation.
The most impressive feature of the movement has been its evolving nature. The underlying theory and the fundamental question that has plagued population ecologists—What factors determine the number and distribution of animals?—remain under debate. Views of the role of pesticides in IPM are likewise evolving. Progress has been made in tailoring pest-specific insecticides with reduced environmental disruption. Although impressive reductions in overall pesticide use have been made in specific programs and levels of insecticide use have declined overall, the IPM era has not resulted in major declines in the total quantities of pesticides used. The euphoria induced by the IPM concept has run its course, and its promise after 3 decades is a subject of lively debate. One of the problems affecting acceptance and support of IPM is the difficulty of assessing its effectiveness. It is a complex system with many obstacles and a restricted database for evaluating a variety of constraints: technical, financial, educational, organizational, and social. Whatever the outcome is, there is no turning back. The human intellect has been unable to construct a more promising strategy for keeping humans’ age-old competitors in check. For millions of people threatened with disease and hunger, IPM constitutes their safety net for tomorrow.
In seeking to understand the strategy employed by applied entomologists, it is helpful to note the historical perspective. Applied entomologists were late to embrace ecology, despite the entreaties of the distinguished president of the Entomological Society of America in 1912, Stephen A. Forbes. He insisted that “the economic entomologist is an ecologist pure and simple whether he considers himself so or not.” In retrospect, it appears that entomologists opted for the certainty of insecticides favored by their farmer clientele over the uncertain promise of ecology. Their adherence to the conventional wisdom of insecticidal control in the DDT era tarnished their image as environmentalists.
I n medical and veterinary entomology, the post-World War II experience with the miracle insecticides paralleled the experience with agricultural pests. First, there was euphoria following the miraculous effectiveness of the insecticides. So promising were the prospects that in 1955 the World Health Organization (WHO) proposed global eradication of malaria. However, the development of resistant strains of vectors and parasites as well as economic and political factors doomed the eradication program. In 1976, the WHO abandoned eradication in favor of more modest programs of control. Research languished under the demoralizing effect of this decision. With anti-malarial drugs and insecticides losing their effectiveness, the battle against malaria was being lost. Alarmed at these developments, the WHO, in 1993, called for a renewed global effort. The initially slow response has gained support, with unprecedented funding available during the initial decade of the 21st century.
An ambitious objective is the development of a vaccine against malaria. Although the scientific obstacles are enormous, significant progress is being made. The most ambitious and futuristic of all approaches to combating malaria is creating a strain of Anopheles gam-biae mosquito unable to transmit the parasite. To displace the native vectors involves three steps: find genes that interrupt the parasite’s life cycle, develop techniques to transfer those genes into the mosquito, and finally, develop ways of replacing existing mosquito populations with the genetically engineered model. One additional hurdle remains. With such a mosquito in hand, there may be strong resistance to releasing such transgenic forms into nature. In the meantime, the disease continues to cast its shadow over the malaria-endemic areas of the world, which are home to 40% of the world’s population.
Advancing the Science
The past 5 decades have witnessed remarkable advances in both applied and basic entomology. The collapse of chemical control of insects forced reassessment, which gave rise to IPM. While the pesticide issue dominated public interest, basic science was forging ahead.
A primary stimulus was the discovery in 1953 that DNA encodes genetic information that provides the blueprint for synthesis and cellular differentiation; this discovery elucidated the great mystery of life, the cells’ ability to self-replicate. Many aspects of biology were catalyzed by the discovery. It dramatically reaffirmed Darwin’s
hypothesis of common descent and revealed evolutionary pathways. Studies of molecular systematics that followed have resulted in accumulation of DNA sequence data that complement and enhance the morphological and ecological data of classical systematics, thereby making substantial contributions to evolutionary biology.
The DNA breakthrough also paved the way for biotechnology, the introduction of genes from various species into plant and animal species. This technology places the cornucopia of biodiversity in the service of agriculture and medicine. But it comes with complex ethical and scientific issues in environmental stewardship and human health. Both scientists and the general public have been aggressive in identifying and have been actively debating the ecological ramifications of introducing genetically modified organisms (GMOs) into the environment.
With biotechnology, plants can be genetically engineered to produce their own pesticides. In 1995, corn and cotton genetically engineered express genes from the bacterium Bacillus thuringiensis (Bt) coding for a protein toxic to several important caterpillar pests were approved for sale in the United States. In 2006, Bt-corn and Bt-cotton were grown commercially on a total of 32 million hectares in 19 countries. Drawing on lessons learned during the insecticide era, entomologists have been aggressively studying the potential environmental and human health risks and benefits relating to the release of GMO crops. They have been proactive in developing deployment strategies for Bt-crops that minimize selection on pest populations to become resistant to the Bt-toxins. Entomologists have also been active participants in the development of the science-based regulatory framework used by the U.S. Environmental Protection Agency and comparable agencies in many other countries to regulate the commercialization and use of Bt-crops.
The benefits of Bt-crops to farmers have been dramatic. In countries where Bt-cotton has been adopted, insecticide use in Bt-cotton has averaged 33-77% less and the effective yield of cotton fiber has increased by average 10-34%, with the greatest gains occurring in developing countries. Industry has been quick to recognize biotechnology’s commercial potential, and substantial segments of the seed market have been given over to GMOs. As the technology has advanced, it has become possible to stack multiple genes conferring an array of different traits in the same crop varieties. GMO corn and cotton varieties are now available. They express multiple Bt-toxins, each effective against different pest species, as well as genes that make the crop tolerant to broad-spectrum herbicides, which can now be used to control weeds after the crop has emerged. Where only stacked-gene varieties are available, farmers requiring only one of the pest management traits have to plant varieties expressing all traits. Questions of a scientific nature are joined by social and economic questions. For instance, should corporate interest determine and control the genetic profile of the three crops—corn, rice, and wheat—that provide sustenance for most of the peoples of the world?
The economic issues surrounding GMOs seem to overshadow the more basic issues they pose. For instance, the biodiversity program seeks to conserve natural forms, whereas biotechnology seeks to replace natural forms with modified ones exempted from evolutionary testing. Over time, how will this practice affect the gene pool and the timeless and priceless biological resource? Will the economic benefits of GMO crops lead to such widespread adoption that they displace the traditional crop varieties and land races that are an important source of genetic diversity used in crop improvement?
Although elucidation of the structure and function of DNA is clearly the most important discovery of the 20th century, other discoveries have greatly advanced our understanding of insects. This progress is largely due to advances in fields such as insect olfaction, acoustics, flight, and communication (e.g., by pheromones). Technological advances have altered the way scientists communicate in person and in professional literature. They became more informed and democratic. The excitement was often centered in youth, in graduate students, with women strongly represented.
The excitement of discovery and exuberant professional exchange produced masses of data, leading to new specialized journals. The worldwide computer network has catalyzed the processing and exchange of data among colleagues on a global scale. The predominant use of English in scientific journals has reduced language barriers. Thus, in both applied and basic entomology, the latter half of the 20th century has represented a new order, new methodologies, new discoveries, and new organizational arrangements. The paths of progress in multifaceted phases of entomology are well documented in the Annual Review of Entomology, published since 1956.
HISTORICAL PERSPECTIVE
The preceding two centuries of entomological enterprise in North America have been directed primarily to two activities: (1) protecting human’s food, fiber, and health and (2) basic research to advance knowledge of insects. These were and continue to be appropriate objectives in the national interest. In the past half-century, the environmental movement and the emerging science of ecology have highlighted two salient points: (1) Insects play a vital role in the sus-tainability of the global biosphere, and (2) the biodiversity essential to sustainability is threatened by human intervention. The factors of habitat destruction, pollution, and introduction of exotic species are believed to account for extinction rates much higher than before the coming of humans. In addition, the ecological impact of global warming looms on the horizon. The movement to preserve biodiversity has been led by Edward O. Wilson (Fig. 3), following publication of his The Diversity of Life (1992). The concept has been generally accepted and is now part of the American culture. The extinction dilemma poses new challenges to the field of entomology and calls for modification of the image entomologists hold of themselves and of the institutions established to deal with entomological matters.
Since the mid-20th century, urbanization of the human population on a global scale has increased at an ever-accelerating rate. By mid-2008, over 50% of the world population will be living in cities. In the United States, as in other developed countries, the shift has been extreme, and the population has been largely separated from its agrarian heritage. This same period saw dramatic advances in physics, chemistry, and the basic biological sciences that have resulted in medical and technological breakthroughs that have spawned unprecedented economic growth. With these advances has come widespread recognition that universities, the centers of basic research, are powerful engines driving growth in the post-agrarian economy, just as they were in the agrarian economy. This recognition has resulted in a shift in funding and infrastructure support to more fundamental and transitional research focused on the economic, environmental, technological, and social priorities of a largely urban populace. The forces of population growth and urbanization are imposing new demands on agriculture to satisfy the global demand for food and fiber. This new order calls for entomological statesmanship that looks beyond entomology’s traditional agricultural constituency to embrace global, environmental, and biomedical issues. The age-old challenge of insect control is being joined by compelling new challenges that entomology must embrace if it is to remain vibrant.
