HISTORY OF BIOLOGICAL PEST CONTROL
Dr. E. F. Legner, University of California, Riverside
The recorded history of biological control may be considered as dating from Egyptian records of around 2,000 BCE, where domestic cats were depicted as useful in rodent control.
Insect Predation was recognized at an early date, but the significance of entomophagy and exploitation was lost except for a few early human populations in Asia where a sophisticated agriculture had developed. The Chinese citrus growers placed nests of predaceous ants, Oncophylla smaradina, in trees where the ants fed on foliage-feeding insects. Bamboo bridges were constructed to assist the ants in their movements from tree to tree. Date growers in Yemen went to North Africa to collect colonies of predaceous ants which they colonized in date groves to control various pests.
Insect Parasitoidism was not recognized until the turn of the 17th Century. The first record is attributed to the Italian, Aldrovandi (1602). He observed the cocoons of Apanteles glomeratus being attached to larvae of Pieris rapae (the imported cabbageworm). He incorrectly thought that the cocoons were insect eggs. Printed illustrations of parasitoids are found in Metamorphosis by J. Goedart (1662) <PHOTO>. He described "small flies" emerging from butterfly pupae. Antoni van Leeuwenhoek in 1700 (van Leeuwenhoek 1702) described the phenomenon of parasitoidism in insects. He drew a female parasitoid laying eggs in aphid hosts. Vallesnieri (1706) <PHOTO> first correctly interpreted this host-parasitoid association and probably became the first to report the existence of parasitoids. Bodenheimer (1931), however, noted that several earlier entomologists recognized the essence of parasitoidism. Cestoni (1706) reported other parasitoids from eggs of cruciferous insects. He called aphids, "cabbage sheep," and their parasitoids, "wolf mosquitoes." Erasmus Darwin (1800) discussed the useful role of parasitoids and predators in regulating insect pests.
During the remainder of the 18th Century an ever increasing number of references to entomophagous and entomogenous organisms appeared in the literature, largely in the form of papers dealing with parasitoid biologies. Diseases of silkworms were recognized early in the 18th Century. De Reamur (1726) <PHOTO> described and illustrated Cordyceps fungus infecting a noctuid larva.
By 1762 the first successful importation of an organism from one country to another for biological control took place with the introduction of the mynah bird from India to the island of Mauritius, for locust control.
Further development of modern biological control awaited the recognition of the fact that insect pest problems were population phenomena. The controversial publications of Malthus appeared toward the end of the 18th Century, and generated considerable interest in the subject of populations. Malthus' work will be discussed further in the next section on "Concepts in Population Ecology."
Biological Control Efforts in the Early 19th Century
A number of articles appeared during the first half of the 19th Century that lauded the beneficial effects of entomophagous insects. Erasmus Darwin (1800) recommended protecting and encouraging syrphid flies and ichneumonid wasps because they destroyed considerable numbers of cabbage-feeding caterpillars. Kirby & Spence (1815) [see <PHOTO>] showed that predaceous coccinellids controlled aphids. Hartig (1827) recommended the construction of large rearing cages for parasitized caterpillars, with the ultimate aim of mass release. Ratzeberg (ca. 1828) <PHOTO> called particular attention to the value of parasitic insects with publication of a large volume on the parasitoids of forest insects in Germany. He did not believe that parasitic control could be augmented by humans. Agustino Bassi (1834) first demonstrated that a microorganism, Beauvaria bassiana, caused an animal disease, namely the muscardine disease of silkworms. Kollär <PHOTO> (1837) writing an article for farmers, foresters and gardeners, pointed out the importance of entomophagous insects in nature's economy; studied parasitoid biologies and was the first to report the existence of egg parasitoids. Boisgiraud (1843) reported that he used the predaceous carabid beetle, Calasoma sycophanta, to successfully control gypsy moth larvae on poplars growing near his home in rural France. He also reported that he had destroyed earwigs in his garden by introducing predaceous staphylinid beetles.
Beginning in 1850, events associated with the westward expansion of agriculture in the United States paved the way for the further development of the field of biological control. During and following the "Gold Rush" in California, agriculture expanded tremendously in California especially. At first the new and expanded plantings escaped the ravages of arthropod pests. Predictably, however, crops soon began to suffer from destructive arthropod outbreaks. Many of these pests were found to be of foreign origin, and were observed to be far more destructive in the newly colonized areas than in their native countries. Consequently, the notion grew that perhaps these pests had escaped from some regulatory factor or factors during their accidental introduction into America.
Asa Fitch <PHOTO> (1855) was the State Entomologist of New York who is recorded as the first entomologist to seriously consider the transfer of beneficial insects from one country to another for the control of an agricultural pest. Fitch suggested that the European parasitoids of the wheat midge, Sitydiplosis mesellana, be sent into the eastern United States.
Benjamin Walsh <PHOTO> supported Fitch's suggestion and in 1866 he became the first worker in the United States to suggest that insects be employed in weed control. He proposed that insects feeding on toad flax, Linaria vulgaris, be imported from Europe to control invaded yellow toad flax plants. The first actual case of biological control of weeds was, nevertheless, in Asia, where around 1865 the cochineal insect Dactylopius ceylonicus was introduced from southern India into Ceylon for prickly pear cactus control (Opuntia vulgaris). Originally Dactylopius had been imported to India from Argentina in 1795, in the mistaken belief that it was the cochineal insect of commerce, D. cacti.
Charles Valentine Riley <PHOTO> (1870) has been named the father of modern biological control. He shipped parasitoids of the plum curculio from Kirkwood, Missouri to other parts of that state. In 1873 he became the first person to successfully transfer a predator from one country to another with the shipment of the American predatory mite, Tyroglyphus phylloxerae to France for use against the destructive grapevine phylloxera. The results were not particularly successful, however. In 1883, Riley directed the first successful intercontinental transfer of an insect parasitoid, Apanteles glomeratus, from England to the United States for control of the imported cabbageworm. He was Chief Entomologist of the U. S. Department of Agriculture. In 1872, 11 years before the importation of A. glomeratus, Riley began his interest in the cottony-cushion scale, Icerya purchasi, which was considered the most important citrus pest in California. He correctly located its point of origin in Australia. [Doutt's account of this biological control program on p. 31-38 of the DeBach (1964) text is particularly colorful. Read this, paying particular attention to the following:
a. the roles played by Riley, Albert Koebele and D. W. Coquillet.
b. note the species of insects involved (the vedalia beetle, Rodolia cardinalis, and the dipterous parasitoid, Cryptochaetum iceryae), their source, numbers imported, and their activities relative to the cottony-cushion scale.
c. note the method of colonization, and be able to describe the spectacular results of these introductions, which changed the status of the pest to an insect of no economic importance in only four years time.
The successful biological control effort against the cottony-cushion scale spirited many biological control attempts in many countries, resulting in over 200 biological control successes (see Chapter 24 of the DeBach (1964) text and other hand-outs).
The cottony-cushion scale success admittedly harmed overall pest control in California for quite some time because growers thought that the vedalia beetle would also control other insect pests. Consequently, they neglected other mechanical and chemical control methods.
George Compere (1899) became the first state employee specifically hired for biological control work. He worked as a foreign collector until 1910, during which time he sent many shipments of beneficial insects to California from many parts of the world. Harold Compere <PHOTO>, his son, also devoted his entire career to the search for and identification of natural enemies of scale insects.
Harry Scott Smith (1913) <PHOTO> was appointed superintendent of the State Insectary in Sacramento. In 1923, biological control work was transferred to the Citrus Experiment Station and Graduate School of Subtropical Agriculture of the University of California, Riverside. Biological control work at Riverside was first conducted in the Division of Beneficial Insect Investigations, and was changed to the Division of Biological Control with Smith as chairman in 1947. Personnel were stationed at Albany and Riverside. Under Smith, importation of Chrysolina beetles from Australia for Klamath weed control marked the beginning of biological weed control in California in 1944.
Edward Steinhaus (1947) <PHOTO> established the first laboratory and curriculum in insect pathology at the University of California, Berkeley. Later he transferred to the newly opened Irvine campus of the University and attempted to further insect pathology there. His untimely death in 1968 precluded this goal.
The Division of Biological Control became the Department of Biological Control at UC Riverside and Berkeley in 1954. In 1969 Biological Control was dropped as a department, becoming a Division of Biological Control within the Department of Entomology, against the wishes of the entire biological control faculty, numbering over 24 academics at Riverside and Berkeley at that time. The Berkeley faculty created their own separate Division of Biological Control with guaranteed privileges and minimum control by the Department of Entomology. At Riverside the Division of Biological Control gradually became dominated by chemical control oriented faculty in the Department of Entomology. In 1989 the Division was abolished, against the wishes of 85% of the faculty in the Division. Ignorance and pecuniary control among the ranks of University of California bureaucrats is believed to be the principal cause. Although the dissenting faculty in the Division each wrote a personal plea to the then Chancellor Rosemary S. J. Schraer to discuss the matter, in not one case was a reply received.
Dr. Joop C. van Lenteren (personal communication) has provided the following summary of the history of biological control:
Prerequisites for a scientific approach to biological control were the general acceptance that insects do not arise by spontaneous generation (F. Redi in 1668) <PHOTO>, the correct interpretation of behavior and development of predators (circa 400 BC in China) parasitic insects (van Leeuwenhoek in 1700) and pathogens, and evolution of the idea to use natural enemies in the control of pests. In Europe, R. Réaumur (in 1734) <PHOTO>, is thought to be the first to propose this tactic: he advised the release of lacewings in greenhouses for the control of aphids.
Early farmers might have already observed and appreciated the action of predators, as predation is obvious and easy to understand. Biological control was first applied before its definition when humans began keeping cats to protect stored grain from rodents, which is actually the earliest recorded history of biological control (Egyptian records date to 2,000 BC). The first biological control project was that of Chinese citrus growers using Oecophylla smaragdina for the control of lepidopteran and coleopteran pests in 324 BC. The ants build nests in trees and such nests were collected and sold to farmers. In order to aid the foraging of ants, bamboo bridges were built between the citrus trees. DeBach (1974) observed this practice still being used in North Burma in the 1950s which was in continued use in China. All early efforts employed general predators such as the mongoose, owls and other birds, toads, ants, etc.
Linnaeus was among the first in modern times to suggest the use of predators for pest control. By 1762 the first successful importation of an organism from one country to another for biological control took place in 1770 with the introduction of the mynah bird from India to the island of Mauritius for control of the red locust Nomadacris septemfasciata.
Insect parasitism was not recognized until the turn of the 17th Century. The Italian U. Aldrovandi (1602) first published an observation on insect parasitism. He observed the cocoons of Apanteles glomeratus being attached to larvae of Pieris brassicae. He incorrectly thought that the cocoons were insect eggs, as he stated, "Twice have I also observed the cabbage caterpillar laying yellow eggs covered with delicate wool, and afterwards transforming itself into a yellowish pupa, marked with green and black. What appeared peculiar to me was that from these eggs emerged small winged animalcules, so small that they could barely be seen..."
Many other parasitoids were drawn by the Dutch, Johannes Goedaert (1662) <PHOTO> in his book Metamorphosis et Historia Naturalis Insectorum. However, in the text he only once referred to parasites, "Out of one caterpillar, which had pupated on June 12, emerged on the 30th the butterfly species.... But out of another caterpillar of the same species, which had pupated on July 13, emerged after pupation 82 small flies, as the reader can see in the figure added. Thus from one caterpillar a butterfly emerged and from the other 82 small flies."
The British physician Martin Lister suggested in letters published in the 1670-71 issue of the Philosophical Transactions of the Royal Society of London, that some insects lay their eggs in the bodies of living caterpillars and in 1685 he correctly interpreted Goedaert's observations, "The 82 flies that emerged from the pupa are the progeny of an ichneumon fly, which had gotten into the caterpillar in a manner that is still not entirely clear to me. In all likelihood they were laid right there by the mother fly..." Another 25 years is required before the cycle of parasitism was fully analyzed and described.
The Dutch microscopist Antoni van Leeuwenhoek in a letter of 26 October 1700 to the Royal Society, published in their Philosophical Transactions in 1701, fully unravelled insect parasitism and his original text is used to illustrate this discovery. In the spring of 1700 he observed that some of the berry trees in his garden in Delft had more flowers than usual. He also observed that the "black flies" on these trees were more numerous than in other years. He was afraid that the offspring of so many blackflies would completely devastate his berry trees. After studying the mouthparts of the "blackflies" he concluded that they would not be able to eat the leaves, "These last flies that I caught were all females, and had their eggs in them; from whence I more strongly concluded that the black flies did the trees no harm; for if they had laid their eggs on the trees, and that all their eggs had produced so many living insects, there would not, I am positive, be one leaf or any fruit remaining on the trees." Leeuwenhoek strongly denied the theory of spontaneous generation, a hotly debated topic during his time. He continued with, "I shifted these flies into another glass tube, where I had before put six green lice [aphids], which I had taken from the leaf of a currant-tree... These flies, as soon as ever they came near the said lice, brought the hinder part of their body, which was pretty long, between all their feet, and stretched their body far out, and their tail making a kind of semicircle with the rest of the body, stood out beyond their head, and in this manner they insinuated their tail into the bodies of the worms, and this the flies did in a short time to all the worms they came near to; but that which was most remarkable in this action was that in this conjunction they never touched the lice, either with their feet or bodies, so that they often essa'd to approach the creatures, in order to thrust in their tails into their bodies, and could not effect it; nay, one would say they were so afraid of these lice as if they would have devoured them; and as they entered the bodies of the lice they made a trillende [shivering] motion of shaking with their tail, which came to be done so that they might thrust it in further."
"Now, as the flies remained but two days alive without copulation, as ever I observed, whereas the green lice lived seven or eight days, I though not otherwise but that the flies by that insinuation of their tails into the bodies of those lice, did withal convey their eggs in the same time, and that from those eggs young worms should have been produced, which having received their nourishment and increase from the bodies of the lice, should be changed again into a fly, but the green lice died, and for the most part dried away. Not content with this observation I got together again 25 dead lice, all of which in their bellies a worm, or else a fly newly changed, for I saw through the skin of some of the lice, living flies, which flies I took out alive from the bodies of some of those green lice which I opened on purpose... Now if we observe the wonderful formation of such a small creature, and how such a fly is produced, and then consider that the worm which is changed into the fly, and we imagine that such a thing will not happen, unless the worm that comes out of the egg of the fly makes use of another creature for its food, we must remain perfectly amazed."
From this description it can be concluded that what van Leeuwenhoek very exactly described was the parasitization behavior of an aphid parasite. The illustration which was published with the letter is of such good quality that the insect could easily be determined to be Aphidius ribis Haliday, a parasite of the aphid Cryptomyzus ribis (L.). Thereafter in the 18th Century, knowledge of parasitoids rapidly increased.
Silkworm diseases were recognized as early as the 18th Century, although diseases of bees were known to the Greeks and Romans. Many publications in the 16th, 17th and 18th Centuries dealt with diseases of silkworms, silk being a very important industry at the time. Vallisnieri was the first to mention the muscardine disease of silkworm. De Reamur (1726) described and was the first to illustrate a fungus, Cordyceps, infecting a noctuid larva. The microbial naturel of these diseases was not yet realized. From William Kirby's <PHOTO> chapter on "Diseases of Insects" (Vol. 4, 1826) of An Introduction to Entomology (Kirby & Spence 1815) we learn that it was recognized that true fungi grew in the bodies of insects as saprophytes and possibly as parasites. Agustino Bassi (1837) first experimentally demonstrated that a microorganism, Beauveria bassiana caused an animal disease, namely the muscardine disease of silkworms. It was also Bassi who suggested in publication in 1836 that microorganisms be used for insect pest control. Later in 1874, Louis Pasteur <PHOTO> suggested the use of microorganisms against the grape phylloxera in France. These suggestions did not result in practical application. Elie Metchnikoff tried to develop biological control for the wheat cockchafer, Anisopilia austriaca, a serious pest of cereal crops in the area of Odessa, Russia. In 1879 he published a paper on Metarrhizium anisopliae, and his experiments led to the conclusion that the fungus, when mass produced and properly introduced in the field, might result in effective control. Based on Metchnikoff's work, Metarrhizium was mass produced in 1884 in the Ukraine, and the spores were tested in the field against a curculionid, Cleonus punctiventris, in sugar beets.
Biological weed control did not start until after 1850. The American Asa Fitch <PHOTO> was the first to suggest biological control of weeds around 1855, when he observed that a European weed in New York pastures had no American insects feeding on it. He suggested that importation of European insects feeding on this weed might solve the problem. The first practical attempt dates from 1863, when Dactylopius ceylonicus, was distributed for cactus control in southern India after they had been observed to decimate cultivated plantings of the prickly pear cactus, Opuntia vulgaris, in northern India (Goeden 1978). In 1865, the first successful international importation for weed control took place, when this same insect was transferred from India to Sri Lanka, where in a few years widespread populations of the same cactus, O. vulgaris, was effectively controlled.
During the 19th Century taxonomy rapidly developed and many biological studies of natural enemies were made. Practical ideas and tests about application of biological control gradually advanced. Erasmus Darwin, the grandfather of Charles Darwin, published Phytologia, a book on agriculture and gardening in 1800, in it stressing the role of natural enemies in reducing pests. Moreover, he suggested that aphids in hothouses by controlled by artificial use of predaceous syrphid fly larvae. Augmentation of ladybird beetles for control of hop aphids in the field and aphids in greenhouses was also suggested by Kirby & Spence (1815).
By 1850 biological control obtained full attention in the United States, where imported pests were taking a large toll of both domestic imported crops. Entomologists, such as Asa Fitch, C. V. Riley <PHOTO> and Benjamin D. Walsh <PHOTO>, suggested the importation of natural enemies from their homeland. It was C. V. Riley who organized the first intra-state parasitoid transport when he sent parasitoids of the plum curculio, Conotrachelus nenuphar, to different localities in Missouri [probably a wasted effort]. Riley was also the first to propose conservation of parasitoids of the rascal leafcrumpler of fruit trees, Acrobasis indigenella, by collecting larvae in their cases in mid-winter and then placing them away from the tree far enough that the larvae could not reach the trees anymore, but the parasitoids emerging from parasitized individuals in springtime could easily do so. Also, in 1873, Riley stimulated the first international transfer of an arthropod predator by sending the predatory mite Tyroglyphus phylloxerae to France for control of the grape phylloxera, Daktulosphaira vitifolii. It established but did not result in effective control. The first international shipment of a predatory insect took place in 1874, when aphid predators, among which Coccinella undecimpunctata, were shipped from England to New Zealand and became established. The first international transfer of parasitic insects was Trichogramma from the United States to Canada in 1882. The first intercontinental parasitoid shipment took place in 1883, when Riley organized the shipment of Apanteles glomeratus from England to the United States for control of cabbage white butterflies. It was just another six years before the spectacular success with Rodolia took place, again under the direction of Riley.
Other texts and files in this series may be viewed by CLICKING on the following:
Secrets of Science <museum1.htm>
History of Biological Control <museum2.htm>
Introduction and Scope of Biological Control <museum3.htm>
National and International Organizations Active in Biological Control <museum4.htm>
Economic Gains and Analysis of Successes in Biological Control <museum5.htm>
Trends and Future Possibilities in Biological Control <museum6.htm>
Beneficial Insects <museum7.htm>
Case Histories of Salient Biological Control Projects <detailed,htm>
Guide to Identifying Predatory and Parasitic Insects <NEGUIDE.1>, <NEGUIDE.2>... etc.
Insect Natural Enemy Photos <NE-2ba.PCX>, <NE-2bb.PCX>... <NE-247ba.PCX>... etc.
Meal Worm Project <project.3.htm>
Ladybird Beetles <ladybird.htm>
Fruit Flies in California <fruitfly.htm>
Killer Bees <killer.htm>
Monarch & Viceroy Butterflies <31aug95.mus.htm>
Everywhere is Home <9feb98.mus.htm>
Familiar Butterflies of the United States & Canada <butterfl.htm>
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