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INTEGRATION OF VARIOUS PEST CONTROL
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The
Political Economy of Biocontrol Research & Research Needs |
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Conditions
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Political
and Economic Framework For Biological Control |
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Difficulties
Encountered in the Measurement of Biocontrol |
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Outline I. The phenomenal
development and increased use of organic pesticides in agriculture after 1945
has been a mixed blessing and has led to heated contemporary debates. A. An attitude of
unreserved optimism became prevalent among most entomologists with demonstrations
of the spectacular effectiveness of DDT. B. Failures of
synthetic organic insecticides to control all pests have changed this
attitude to a more rational but somewhat pessimistic one. C. Development of
insecticide resistant populations, resurgence of treated pest populations,
evaluation of secondary pests (or in some cases previously innocuous species)
to a status of primary importance, deleterious effects on populations of
nontarget organisms, and general pollution of the environment with measurable
residues of persistent chemicals have posed increasingly critical problems. II. It
is not surprising, then, that considerable interest has been shown in recent
years in Integrated Pest Management (IPM).
or the ecological approach. III. The term "Integrated Control" apparently was first
proposed by Dr. Blair Bartlett, University of California, Riverside in 1956,
although the first actual demonstration of the technique was by the Swiss
entomologist, F. Schneider in Sumatra in the 1940's and working on gambir
plantations. A. Bartlett used the
term to designate applied pest control that combines and integrates
biological and chemical measures into a single unified pest control program. B. Chemical control is
used only where and when necessary, and in a manner that is least disruptive
to beneficial regulating factors of the environment, particularly naturally
occurring arthropod parasitoids, predators and pathogens. IV. In the early 1960's the first
suggestions arose for broadening the concept to include the integration, not
only of chemical and biological control method, but of all practices,
procedures and techniques relating to crop production, into a single unified
program aimed at holding pests at subeconomic levels. Thus, the concept
evolved from a two-component system (chemical and biological control) to the
much broader concept of pest management. V. All the proposed
definitions have one common theme: the system must be based on sound
ecological principles. VI. Terms frequently
used in discussions of integrated pest management: A. Each species of
arthropod pest occurring in our various agricultural ecosystems falls into
one of three categories: key pest, occasional pest, or potential pest. B. Usually one or two key pest species are common to each agricultural ecosystem,
these being those serious, perennially troublesome species that dominate
control practices. C. Occasional
pests, in contrast to key pests, are those arthropods that only cause economic
damage in certain places in certain years. Such pest are usually under
adequate biological or natural control which is disrupted occasionally or
fails for various reasons. D. Potential pests are those species which normally cause
no economic damage, but as a result of chemicals or cultural practices are
allowed to realize their potential for damage. 1. Basic to the concept
of integrated pest management is the notion that most potential pests have
effective natural enemies. All but the most sterile human-made environments
have some biotic agents that influence pest populations; and due
consideration should be given to the conservation or augmentation of these
agents during the development of pest control programs insufficient ( Legner 1970, 1987 , Legner &
Olton 1968, 1970 , Legner & Sjogren 1984, 1985; Legner et al.
1974, 1975, 1981 ; Oatman 1962). 2. Also basic is the
concept that the ability of natural enemies to effect only partial control of
a pest should not invoke chemical control practices that disrupt either this
partial control or the controlling action of natural enemies of other
potential pests in the agricultural ecosystem. VII. Pest-Upset versus
Pest Resurgence. A. Pest-Upset. 1. cotton leaf
perforator, a lepidopterous cotton defoliator, apparently native to the
Southwestern United States, was inconspicuous until about 1965. 2. it became a cotton pest
coincident with the massive blanket application of insecticide in the lower
Sonora Desert cotton-growing areas, for the eradication of the newly
introduced pink bollworm. B. Pest Resurgence. 1. represents a rapid
return to economic prominence of a pest whose abundance was initially
suppressed by a pesticide that, however, destroyed its natural enemies. 2. this type of
outbreak commonly results whenever pesticides destroy the partially effective
natural enemies of a pest species. 3. pest resurgences
often generate a need for increasingly frequent pesticide applications as the
effects of additional natural enemy destruction accumulate with each
treatment. VIII. Sole reliance on chemicals for pest
control has the following drawbacks: A. Selection of resistance
to insecticides in pest populations. Cross resistance also is hastened. B. Resurgence of
treated populations. C. Outbreaks of
secondary pests. D. Residues, hazards
and legal complications. E. Destruction of
beneficial species, including parasitoids, predators and pollinating insects. F. Expense of
pesticides, involving recurring costs for equipment, labor and material. A.
"Selectivity" defines the capacity of a pesticide to spare natural
enemies while destroying their pest host. B. Two types of
selectivity: 1. physical: arises
from differential exposure of pests and natural enemies to a pesticide. 2. physiological:
arises from a differential inherent susceptibility on the part of the pest
and its natural enemies to a pesticide. X. Factors that can determine physical
selectivity. A. Preservation of
natural enemy reservoirs during treatment, either within treated areas or
within easy migrational distances from them. 1. maintain adjoining
untreated crop areas or stands of untreated alternate host plants. 2. recolonizing treated
areas with mass-reared natural enemies. 3. staggering chemical
treatments of portions of large plantings. 4. employing spot or
strip treatments of chemicals. B. Timing pesticide
treatments to allow for the differential susceptibility and seasonal
occurrence of the various developmental stages of natural enemies. 1. the pupal and
prepupal stages of parasitoids are relatively immune to pesticides. 2. the eggs of many
predators are laid in protected spots or are otherwise inherently
unsusceptible. 3. adult parasitoids
and predators are generally the most susceptible stages. C. Physical selectivity
may also be conferred by the feeding habits of various natural enemies. 1. internal parasitoid
larvae are protected within their hosts from contact poisons. 2. adult entomophagous
insects vary in susceptibility to stomach poisons in relation to their
propensity to ingest insecticide contaminated hosts, plant exudates or
honeydew. D. Physical selectivity
also can be conferred by manipulating the dosage and persistence of
pesticides. XI. Physiological
selectivity is conferred by a pesticide that is more toxic to a pest species
than to its natural enemies. But, unfortunately, the reverse is usually true. A. A few pesticides have
been developed that are fairly specific against certain groups or species of
arthropods. B. Physiological
selectivity is a costly achievement. The costs involved in the research and
development of pesticides are tremendous, well in the range of 20-40 million
dollars per compound. If more of the highly specific pesticides are to be
developed for integrated control, something probably will have to be done to
offset those tremendous developmental costs to industry, for obviously the
marketing potentials of selective and specific pesticides are much less than
those of broad-spectrum compounds. C. To make matters
worse for industry, successful integrated control programs have resulted in
smaller demands for pesticides and a reduced demand for broad-spectrum compounds.
The continuation of this trend could deter industry from trying to find
additional specific compounds with limited market potentials. XII. Pest Management Conflicts (See Discussion) ------------------------------------------------------------------------------------------------------------------------------------------------- Van Driesch
& Bellows (1998) Account (Selective
Pesticides) Physiologically Selective Pesticides Ecologically
Selective Ways of Using Pesticides Selective
Formulation & Materials Creation and
Use of Pesticide-Resistant Natural Enemy Populations ----------------------------------------------------------------------- Physiologically Selective Pesticides. Van Driesche & Bellows (1999) observed that these pesticides
are discovered by systematic testing to identify which of those available and
effective for the control of the pests of the crop are also relatively
harmless to the natural enemies to be conserved. Because populations of
natural enemy species collected from different locations may differ in their
susceptibility to a pesticide (Rosenheim and Hoy 1986; Rathman et al. 1990;
Havron et al. 1991), susceptibilities must be measured for the local
populations of natural enemies actually of interest. Also, information about
effects of one pesticide is often not useful in predicting the toxicity of other
pesticides to a given natural enemy or to other natural enemies (Bellows and
Morse 1993). These facts dictate that only comprehensive local testing of
pesticide-major natural enemy combinations can fully define which materials
may be safely used in a crop (for spiders and brown planthopper on rice in
the Philippines, see Thang et al. 1987). In western Europe, all pesticides
are tested against eight standard species of natural enemies to partially
characterize their likely risk to natural enemies (Van Driesche & Bellows
1999). Test methods are sensitive to the precise conditions selected for
the assay. Careful attention is given to standardizing the source, age, sex,
and rearing history of the natural enemies used in tests, as well as the temperature,
relative humidity, and degree of ventilation of the test environment, and the
formulation, purity, and dosage of the test material (Croft 1990). The use of
standardized assay conditions, such as those developed by the IOBC
(International Organization for Biological Control) is critical if studies
are to be compared (Hassan 1977, 1980, 1985, 1989a; Hassan et al. 1987; Morse
and Bellows 1986). Basic to many such tests is the simultaneous testing of
the pest organism under the same conditions as the natural enemies to
determine whether differences in susceptibilities exist. Usually, pests are
less susceptible to pesticides than are their natural enemies. Methods for such screening range from laboratory tests, through
semi-field tests to field studies. Laboratory methods include treatment of
natural enemies through ingestion of pesticide or pesticide-treated
materials, topical application, and placement of natural enemies on freshly
dried pesticide residues on surfaces on which natural enemies are forced to
rest. The slide-dip technique in which organisms are immersed in a pesticide
solution is commonly used for tests with mites. Exposure to residues on test
surfaces can involve glass, sand, or leaves as the test surface. Foliage may
be sprayed in the laboratory or field, and used either immediately after
drying, or after aging for various lengths of time under field or
standardized laboratory conditions. Semi-field tests involve confining test
organisms on parts of plants or whole plants, after treatment of foliage with
pesticides. Field tests involve assessing impacts on natural enemy
populations when whole fields or plots are treated with pesticide. In field
tests, the use of small, replicated plots is often unsatisfactory because
natural enemies are mobile and poor separation of treatment effects occurs.
The use of large unreplicated plots, with repetition over time, often gives
more satisfactory results (Brown 1989; Smart et al. 1989). Methods used to express degrees of susceptibility to pesticide include
the size of the dose that kills half of a sample of the test organisms
(LD-50). Where organisms are not orally or topically dosed, but rather
confined on a treated surface, the measure LC-50 is used, which is the
concentration of solution applied to a treated surface that kills half of the
test organisms in a defined period of time (usually 24 or 48 h), Tests which
incorporate measurement of effects of pesticide residues of various ages
(aged under either natural or defined environmental condilions) are
especially helpful in defining the period of risk that particular species of
natural enemies experience after a pesticide application (Bellows et al.
1985,1988,1992a, 1993; Morse et al. 1987; Bellows and Morse 1988). The ratio
of the LC-50 values of the natural enemy and the pest, or that of the natural
enemy to the recommended application rate for a pesticide is a useful
comparative measure of the selectivity of a pesticide (Morse and Bellows
1986, Bellows and Morse 1993). Assessment of natural enemy performance (ability to encounter and
subdue prey successfully or, for parasitoids, to locate and oviposit in
hosts) is a better indicator of the total effect of pesticide residues than
is mortality because it also incorporates the sublethal effects of pesticides
on natural enemies. Ecologically Selective Ways of Using Pesticides. Pesticides can be
used in various ways that reduce contact with natural enemies (Hull and Beers
1985). Reduced Dosages. Effects of pesticides on natural enemies can be decreased by
reducing the dosage applied (Poehling 1989). Use of half or quarter rates of
pesticides often provides adequate pest control while reducing natural enemy
mortality. Selective Formulation & Materials. The physical characteristics of pesticide formulations influence
their impact on natural enemies, Granular formulations applied to the soil,
for example, do not contact natural enemies on foliage or in the air and
hence many natural enemies are unaffected by such applications (Heimbach and
Abel 1991). However, such materials are often designed for the purpose of
producing pesticide residues in the topsoil and, in that zone, contact with
natural enemies may be prolonged and extensive; such applications would be
expected to significantly reduce susceptible natural enemy populations that
live in the soil or forage on its surface (Van Driesche & Bellows 1999).
Systemic pesticides do little direct damage to natural enemies which do not
consume plant sap and thus do not contact the pesticide (Bellows et al. 1988).
Pesticides that kill only if ingested, rather than by mere contact with the
integument, are less likely to harm natural enemies (Bartlett 1966). Stomach
poisons such as some pathogen-derived materials, plant-derived materials or
mineral compounds are usually not damaging to predators and parasitoids which
do not eat plant tissues. Nevertheless, even stomach poisons can be harmful
to natural enemy populations if they cause drastic reductions in host or prey
densities (Van Driesche & Bellows 1999). Treatment Area Limitation. The extent of the area treated with pesticides can be adjusted
to reduce exposure of natural enemies. For instance, the treatment of
alternate rows instead of entire blocks in apple orchards controls mobile
orchard pests, but allows greater survival of the coccinellid mite predator Stethorus punctum (LeConte)
(Hull et al. 1983). DeBach (1958) successfully controlled purple scale, Lepidosaphes
beckii (Newman), in citrus by applying oil to every 3rd row on a 6-month
cycle. This provided satisfactory control of the pest without destroying
natural enemies of other citrus pests. Velu & Kumaraswami (1990) found
that treatment of alternate rows in cotton to provide effective pest control
and, for some of the chemicals tested, enhanced parasitism levels of key
pests. Contrarily, Carter (1987) found that strip spraying of cereals in
Great Britain did not provide satisfactory control of aphids when strips were
12 meters wide because the natural enemies did not colonize the sprayed
strips in time to suppress aphid resurgence. Application Time Limitation. Contact between pesticides and natural enemies can be limited by
using either nonpersistent materials, making less frequent applications, or
applying materials in periods when natural enemies are not present or are in
protected stages. Using nonpersistent pesticides reduces damage to natural
enemy populations because natural enemies that emerge after toxic residues
have declined (from inside protective structures such as cocoons or mummified
hosts) can thus survive. Also, natural enemies that arrive from untreated
areas can recolonize treated fields sooner. Persistence of pesticides varies
greatly. Materials such as diazinon or azinphosmethyl leave residues on
foliage and other surfaces for more than one week at levels that kill natural
enemies. Some herbicides, such as the triazines, applied to soil last for
months. Other materials, such as the insecticide pyrethrin, degrade in hours
or days. Weather conditions affect persistence of pesticide residues. Rain is
most important as it can wash residues off surfaces, and temperature may
influence both the toxicity of the pesticide and the rates of dissipation and
degradation of residues. Adjustment of timing of pesticide applications to protect natural
enemies is a matter either of reducing overall spray frequency so that there
are times when the crop foliage is not toxic to natural enemies, or changing
the exact timing of particular applications to avoid periods when natural
enemies are in especially vulnerable life stags. Gage & Haynes (1975),
e.g., used temperature-driven models of insect development to time pesticide
applications against adult cereal leaf beetle, Oulema melanopus,
treating after beetles had emerged, but prior to emergence of the parasitoid Tetrastichus
julis (Walker). This system conserved the parasitoid, while the previous
approach of direct pesticide-applications at the first generation of cereal
leaf beetle larvae (the stage attacked by the parasitoids) did not. Efforts
to redirect pesticide applications to periods when natural enemies are less
vulnerable may require that natural enemy populations be monitored to
determine when susceptible natural enemy stages are present, with the goal of
creating pesticide-free times around critical periods. Monitoring methods
have been employed to detect adults of some parasitoids to aid in their
integration into crop management systems as, for example, with parasitoids of
California red scale, Aonidiella auranti, on citrus in South Africa
(Samways 1986) and parasitoids of San Jose scale, Quadraspidiotus perniciosus
(Comstock), in orchards in North Carolina (U.S.A.) (Mc Clain et al. 1990). If
many pesticide applications are required, it becomes increasingly difficult
to avoid periods when natural enemies are in vulnerable life stages. Redesigning the System. Options for the conservation of natural enemies are increased
when the need for repeated use of broad spectrum pesticides is eliminated
through the development of nontoxic pest control methods (such as use of
natural enemies or other methods including traps, mating disruption with
pheromones, and cultural methods). Reduced frequency of pesticide use in a
crop is likely to greatly increase the survival and population densities of
natural enemies, as in pear (Pyrus communis L.) orchards in Oregon,
when mating disruption (based on pheromones) was substituted for
organophosphate pesticides for control of codling moth, Cydia pomonella
(L.). This substitution raised the densities of the predacious hemipteran Deraeocoris
brevis piceatus Knight and the lacewing Chrysoperla carnea (Stephens),
resulting in an 84% drop in densities of the pear psylla, Psylla pyricola
F6rster, and a reduction of fruit contamination by honeydew from 9.7% to 1.5%
(Westigard and Moffitt 1984). Creation and Use of Pesticide-Resistant Natural Enemy Populations. Where pesticides are applied to crops and no sufficiently
selective material or method of application can be discovered, attempts have
been made to release and establish pesticide-resistant strains of key natural
enemies. The intent of such releases is to permanently establish the
pesticide-resistant form of the natural enemy so that pesticides may continue
to be applied for other pests, while not disrupting control of the pest
suppressed by the resistant natural enemy (Van Driesche & Bellows 1999). Pesticide-resistant strains of several species of phytoseiid
mites have been developed by laboratory selection or recovered from field
populations, including Metaseiulus occidentalis (Nesbitt) (Croft 1976;
Hoy et al. 1983; Mueller-Beilschmidt and Hoy 1987), Phytoseiulus
persimilis (Fournier et al. 1988), Typhlodromus pyri and Amblyseius
andersoni (Chant) (Penman et al. 1979, Genini and Baillod 1987), and Amblyseius
fallacis (Whalon et al. 1982). Resistant strains of parasitic Hymenoptera
have also been isolated from field populations and resistance levels to some
pesticides further augmented by laboratory selection. Species have included
an aphid parasitoid (Trioxys pallidus Haliday, Hoy and Cave 1989), a
leaf miner parasitoid (Diglypbus begini [Ashmead], Rathman et al.
1990), and some scale parasitoids (Aphytis holoxanthus DeBach, Havron
et al.and Aphytis melinus DeBach Rosenheim & Hoy l988). Studies of these organisms have demonstrated that for many
natural enemies genetic variability exists that permits the development of
pesticide-resistant populations under field or laboratory selection. In
several instances, it has been demonstrated that these strains can establish
and survive for one or more years in commercial fields or orchards where
pesticide applications are made (Hoy 1982b; Hoy et al. 1983; Caccia et al.
1985). initial establishment of resistant strains is fostered by prior
destruction through pesticide application of any existing susceptible
population of the same species (Hoy et al. 1990). Long term persistence of
the resistant strain is needed if economic costs of strain development are to
be offset by prolonged benefit. In some cases, such as the use of Phytoseiulus
persimilis for mite control in greenhouse crops, no susceptible strain is
present, and it is sufficient merely for the resistance to last for the life
of the crop (usually 3-6 months), because new predators will be released in
future crops (Fournier et al. 1988). In outdoor crops, maintenance of the
resistant strain may require regular pesticide application. Where such
applications are employed, introductions of pesticide resistant natural
enemies can lead to their replacement of existing, pesticide-susceptible species
(Caccia et al. 1985). In the absence of such ongoing pesticide usage, the
introduced strain of resistant natural enemy may be displaced by other,
pesticide-susceptible species (Downing and Moilliet 1972). The importance of
the level and sustained nature of pesticide selection to the establishment of
resistant strains of natural enemies in the field has been pointed out by
Caprio et al. (1991). In some cases, the need for continued treatments in the
field to retain resistance in natural enemies may be met by pesticide
treatments made for other pests in the crop system, Trials in Great Britain
with an organophosphate-resistant strain of Typhlodromus pyri showed
survival of the predator in orchards treated with organophosphate
insecticides at levels sufficient to control Panonycbus ulmi (Koch)
and Aculus schlechtendali (Nalepa). In a pyrethroid-treated orchard
this strain of T. Pyri was scarce and did not suppress pest mites
(Solomon et al. 1993) Conservation Philosophy. Effective conservation of natural enemies through either
physiological or ecologically selective pesticides involves changes by
growers in outlook as well as technological changes in procedure (Van Driesch
& Bellows 1999). Crop production systems based on biological control seek
to use pesticides as supplements to natural enemies, not substitutes for
them. Emphasis on obtaining a high level of pest control from pesticide
application is likely to be detrimental when biological control agents are
part of the system. Pesticides can be integrated more effectively with
natural enemies when used so as to inflict only moderate levels of mortality
(30-600/o) on unacceptably high pest populations, when natural enemy action
has been insufficient ( Legner 1970, 1987 , Legner & Olton 1968, 1970 , Legner & Sjogren 1984, 1985;
Legner et al. 1974, 1975, 1981 ; Oatman 1962). If pesticides,
of whatever degree of physiological or ecological selectivity, are used at
rates and frequencies designed to provide the first and basic means of
control, natural enemy populations are likely to be too disturbed by loss of
their host or prey to provide any significant level of control in the system. CONDITIONS
FAVORING THE ADOPTION OF BIOLOGICAL
CONTROL STRATEGIES The social and economic factors which affect research and
implementation of biological control were examined by Perkins & Garcia
(1999). They state that the ability to predict and control organisms in a
socially and economically desirable way is central to successful biological
control strategies. Two considerations in biological control work are (1) a
proposed biological control scheme manageable in a biological sense; that is,
do the organisms behave in predictable and reliable ways; (2) can the
organisms be manipulated in ways that are socially and economically feasible.
This question raises issues in social sciences, politics and philosophy. Although biological control researchers have had a history of
successful practice, advocates of this approach to pest control believe their
knowledge has not been fully utilized. Since the discovery of DDT's
insecticidal properties in 1939, researchers in biological control have been
sensitive to the competition with chemical control. They feel that the
failure of biological control to be more widely adopted originates from
social and economic issues rather than from a failure of biological knowledge.
To explore how social and economic factors affect biological control it is
necessary to define the meanings and scope of social and economic factors.
Perkins & Garcia (1999) do this by outlining the political economic
framework of biological control science. The definition of biological control
itself is contested, and it is important to state clearly the definition used
in an analysis. Political
and Economic Framework For Biological Control Political economy examines the interactions between how resources
are created, distributed and used, and the exercise of power and control. One
can see the links between economic and political power that derive from
ownership of factories and machines. The owners, either individuals or
corporations, decide what will be made, how the product will be distributed
and how the proceeds from the sales will be allocated. The power of ownership
is not absolute, but compared to the work force the owners have more power
within the boundaries of the manufacturing plant. This power and wealth can
be used to influence the general political process of a country and is more
influential than that exercised by the non-owner groups. Similarly, ownership
of land creates power to make economic decisions that affect the welfare of
the work force and of consumers of the lands' products. Owners of land tend
to be wealthier than non-owners, and they exercise influence in the political
process that is not available to non-owners (Perkins & Garcia 1999). The creation and use of scientific and technological knowledge
have attributes similar to the creation of other forms of wealth. Research
and development occurs in laboratories and field stations that are owned and
controlled by corporations, government agencies or universities. The
researcher has more autonomy than a factory work, but this should not obscure
the employer-employee relationship that exists between the working scientist
and the laboratory administration. The ability of a researcher to work
depends critically on convincing the administration that proposed research
would yield a useful product, or knowledge that the administration wants to
have created. Once developed, the scientific or technical knowledge may be
owned and controlled by the administration. On the other hand, the knowledge
may become part of the public domain and transfer to economic decision makers
who have interest in and influence with the laboratory administration. Pest control has been developed principally in agricultural
research stations, public health laboratories and the private chemical
industry. Biological control has been developed almost exclusively within
agricultural research stations, which are supported by government and
universities. Biological control information is largely non-proprietary and
in the public domain. Although since 1980 some aspects of biological control
knowledge have been developed by private, profit-seeking firms, the
contributions of these companies are small. Despite the free appearance of biological control knowledge, it
would be wrong to assume that issues of power and control were not involved
in the creation of this expertise or that future developments in biological
control will be remote from questions about the exercise of political power.
The allocations of budgets for agricultural research are highly politicized
events (Guttman 1978, Rose-Ackerman & Evenson 1985). Some lines of
research are favored over other, and political leaders in legislatures,
executive branches and university administrations are sensitive to the demands
of powerful constituents (Perkins & Garcia 1999). Commercial agriculture is becoming increasingly competitive, and
farmers, particularly in North America, have had productive capacities in
excess of markets. The result is that farmers have been in an economic race
to use the best technology to lower production costs and increase profits.
Biological control must be applied to this highly competitive farm industry.
Some research has addressed problems of urban, forest and public health
issues, and such are expected to expand in the future. But, much of the
political fortune of biological control will continue to be based on an
ability to serve the farming industry. Individuals, partnerships,
corporations, cooperatives or the state may control farming; but in each case
they must behave as profit centers and atomistic entrepreneurs competing
against other farm firms (Perkins & Garcia 1999). Other forms of pest
control technology compete with biological control in the sense that farmers
usually have options among several technical practices. Farm managers,
legislators, executives and university administrators will be attuned to the
abilities of biological control expertise to function commercially. The
exercise of political power around biological control research will revolve
about the abilities of the expertise to function within the economic
framework of agricultural enterprise that produces for a competitive, global
market. Perkins & Garcia (1999) suggested that a political economic
analysis of the creation of biological control technologies must examine
several issues and events as follows: (1) Resources for scientific
investigation must be allocated before scientific knowledge can be developed.
Part of understanding how social and economic factors affect biological
control involves understanding the resource allocation process for biological
control research. The allocation process is political and influential parties
try to direct research resources in ways that will protect and enhance their
interests. (2) Once knowledge is articulated, questions arise about its
usefulness. These questions center on the goodness of fit of the new
technical knowledge to the complex of operations involved in agriculture. Is
the technology cost effective? Can the user receive training and advice on
how to use it? Is the new technology compatible with the user's other
production practices? Does the new practice fit within the user's traditional
activities. Does the new practice fit the habits of how the user relates to
government authority, presumptions and traditions? Does the new user have to
adopt new assumptions about nature or the state to feel positive about trying
the new knowledge? The Importance of Defining
Biological Control.--Harry Smith (1919) defined biological control as follows:
"The biological method of insect pest control... embraces the use of all
natural organic checks, bacterial and fungous diseases as well as parasitic
and predacious insects... From a practical stand point, the biological method
may be arbitrarily divided into two sections: First, is the
introduction of new entomophagous insects which do not occur in the infested
region; and second, the increasing by artificial manipulation, of the
individuals of a species already present in the infested region, in such a
way as to bring about a higher mortality in their host than would have
occurred if left to act under normal conditions." Since 1919, researchers have expanded and refined the definition
of biological control. Recently the scope and content of the definition have
become important public policy issues. In 1987, the Committee on Science,
Engineering and Public Policy (COSEPUP) of the National Academy of Sciences,
National Academy of Engineering and the Institute of Medicine, advocated an
expanded definition of biological control: "...the use of natural or
modified organisms, genes, or gene products to reduce the effects of
undesirable organisms (pests), and to favor desirable organisms such as
crops, trees, animals, and beneficial insects and microorganisms."
(COSEPUP 1987). This expanded definition has not been accepted by the
Division of Biological Control, University of California, Berkeley, because
the COSEPUP definition fails to provide essential and clear distinctions
between different pest control technologies (Garcia et al. 1988), which are
(1) self-sustaining control compared to control requiring continual input,
and (2) density-dependent action characteristic of true biological control
compared to the density-independent action of other suppression technologies.
It was suggested that the essence of biological control was best described in
a definition by DeBach (1964): "...the action of parasites, predators,
or pathogens in maintaining another organism's population density at a lower
average than would occur in their absence." Difficulties Encountered in the
Measurement of Biological Control.--It is impossible to
know how social and economic factors affect research and implementation in
biological control without knowing how these activities have fared in the
past. Unfortunately, the ability to trace research and implementation in
biological control are limited, especially when attempting to quantify the
trends, as is discussed in other sections. It is possible to make
quantitative estimates of research output and personnel levels in biological
control for some periods and world areas. Quantitative estimates of research
output, levels of research support and number of scientifically trained
personnel engaged give only partial insights into the success of a scientific
enterprise. Qualitative considerations are important to assessing a research
area. Prominent governing factors are the goals and methods involved, the
quality of training, morale, the location of the institutional base within
the framework of power and the relationships between scientific personnel and
their clients (pest control decision makers) who must ultimately use the
knowledge generated. The number of scientific papers published, personnel and amounts
of funds expended on biological control research do not always indicate the
quality of a research operation. Complex considerations surround our ability
to understand the fate of biological control at the implementation stage.
Biological control researchers have periodically issued compilations of
"successes" sometimes as part of an effort to generate social and
political support for their programs (DeBach 1974, Huffaker & Messenger
1976, Commonwealth Agricultural Bureaux 1980, Legner 1987 ). Unfortunately,
social and economic information gathered in listing successful biological
control events is limited to the amount of damage done by the pest before and
after the biological agent was introduced. The difference between the before
and after damages are then considered to be the value of the biological
control agent. Such figures are often impressive, because some examples of
biological control show enormous returns for small amounts of money invested.
Insights into the factors affecting the use of biological
control, however, are difficult to draw from such studies because the
behavior of all the organisms involved is not established and the interests
of the pest control decision makers are often confounded with those of the
biological control researcher. Such confusion is understandable because in
classical biological control the researcher and the implementor are often the
same person. If classical biological control were the only valuable mode of
biological control then we would not be concerned with factors affecting
decision makers such as farmers. Only the forces governing the amount of
research in biological control would be considered because farmers would be
the recipients of a new technology that is delivered to them without their having
to take positive action. Augmentative and conservatory biological control,
however, are now substantially shifting the form of biological control
technology. Implementation of biological control through augmentation and
conservation of natural enemies is virtually certain to require changed
behaviors on the part of a pest control decision maker who is different from
the researcher. In such cases the behavior and interests of the implementor
must be distinguished from the scientist, or it will be impossible to analyze
the factors affecting implementation. It must be known, for example, how the
decision maker formulates long term goals. What sort of knowledge inputs are
likely to appeal to the aspirations, experience and constraints within which
the decision maker works? To what extent do economic factors interact with
more subtle social, political and philosophical considerations? Failure to
understand the actions of decision makers will lead to frustration for
researchers and policy makers who believe that biological control offers
substantial benefits. Resource Allocation
For Research Trained personnel, supportive institutions and funds are required
for research. Sources of public and private funds are primary social and
economic factors affecting the research enterprise in biological control.
Past performance indicates that the biological control research community is
a vigorous and vital group generating new results, conceptual and
methodological tools and successful control schemes. These indicators include
(1) the output of literature in biological control, (2) the staffing levels
in research organizations, (3) the signs of intellectual vigor in
institutions essential to biological control research and (4) the
introduction of exotic species in programs of classical biological control
(see section on case histories). Size of Research Effort.--It is difficult to estimate the size of the biological control
research community and its productivity, as there is not tracking the number
of scientists involved, their levels of productivity, the levels of funding
provided and the number of projects completed. Some educated guesses may be
obtained, however. Abstracts of scientific papers, reports and books in biological
control are published in Biocontrol News and Information
(BNI), a publication of CAB International Institute of Biological Control
(formerly the CIBC or Commonwealth Institute for Biological Control). BNI has
been published regularly since 1980, and the number of abstracts published
per year is the only global estimate available for the size of the worlds's
biological control literature. The number of abstracts may be constrained
more by budget limitations of CAB than by the number of literature entries
available. The BNI database provides a minimal estimate of scientific
activity in biological control. Since 1980 the average number of abstracts
per year in BNI has been 2,421. (please see Anonymous 1985b, Perkins &
Garcia 1999). The some 2,400 literature messages which are produced in
biological control per year is of interest because it allows a rough estimate
of the number of scientist years involved in the biological control research
enterprise. If it is assumed that one full time efficient scientist can
produce 1-4 messages per year, then a production of 2,400 messages per year
implies that the world has at least 600-2,400 scientist years working in
biological control. Many personnel involved are part time in their research
activities, so more individuals are involved than scientist years. In addition
the estimate of 1-4 messages per year for the average scientists cannot be
verified and some work in biological control does not result in publication. Judd et al. (1987) estimated the global resources for agricultural research
to be 148 thousand scientist years in 1980. Research in biological control is
thus about 0.4-1.6% of the total research in agriculture in terms of manpower
allocations. Agricultural science resources are not evenly distributed over
the world, and historically agricultural research was conducted primarily in
industrialized countries. In 1959, 19% of the manpower and 76% of the funds
for agricultural research were spent in Europe, the U.S.S.R., North America
and Oceania. By 1980, more rapid increases in third world agricultural research
caused the proportion of resources expended by the industrialized world to
drop to 57% of the manpower and 69% of the funds. Agricultural research is
still an activity dominated by developed countries (Judd et al 1987, Perkins
& Garcia 1999). It is not unexpected, therefore, that biological control
researchers are concentrated in certain areas. A recent report of the U. S.
Department of Agriculture estimated that ca. 190 scientist years were devoted
to biological control work in the USDA laboratories and agencies (USDA 1985).
Biological Control and Pest
Control Science.--A
recent renaissance has been experienced in the biological control of insects.
Perkins & Garcia (1999) suggest that biological control enjoyed a wave of
rising popularity among researchers from 1920 to 1945 and then went into a
decline, probably as a result of enthusiasm for research on the newly
introduced synthetic organic insecticides. After a low in 1955, the fashion
of doing research in biological control began to climb again, and the
proportion of entomological papers now devoted to biological control is ca.
25%, which is about equal to the previous high of ca. 28% in 1940 (Anonymous
1981, Perkins & Garcia 1999). Confirmation that enthusiasm for research on insecticides
eclipsed biological control work was also noted by Price-Jones (1973) who
sampled articles from the Journal of Economic Entomology.
Similar conclusions were reached by Perkins (1978) in a study on how the introduction
of DDT to the United States affected research by American economic
entomologists. Perkins (1982) analyzed the changes in direction of one
American research entomologist in the 1940's and 1950's and concluded that
the technical capabilities of insecticides were responsible for a strong
shift in research interests away from biologically based means of control
towards chemically oriented technologies. Biological Control Research Organization.--The proportion of entomological papers devoted to biological
control has increased markedly since 1960 to over 2,000 per year (Anonymous
1985b). Before this time there were no more than 400 papers in biological
control in any one year. Developments in organizations and research also indicate that
biological control is gradually being vitalized. The CAB International
Institute for Biological Control is the largest multinational network of
scientists engaged in biological control research. It was reorganized in 1985
to make it more useful to a wider range of clients (Anonymous 1985a). The
Institute currently operates on ca. 1 million British pounds sterling per
year (US $1.7 million), up 240% from its 1979 levels (CAB 1985). Many of the
funds are expended for projects in developing countries and in Canada (CAB 1986,
Perkins & Garcia 1999). The U. S. Department of Agriculture is the world's largest
agricultural research organization. It has made substantial changes in its
biological control effort during the past 50 years. It had an active program
of foreign exploration that was reduced during World War II. For 15 years no
effort was made to revive the former program, but in 1955 plants to expand
the work, primarily in augmentative biological control, were made. A major
laboratory began operations in 1963 (Perkins 1982), and the USDA in the
1980's began a comprehensive effort to rationalize and coordinate biological
control work (USDA 1984, 1985). Another example of continuing vitality in biological control is
seen in the number of publications appearing in Entomophaga,
which has been published in France by the International Organization for
Biological Control since 1956. This journal is supplemented by publications
such as the Chinese Journal of Biological
Control (since 1985) and Biocontrol News and Information (since 1980). Expansion of Biological Control
into New Study Areas.--There have been completely new industries and new areas of
study begun since 1980 which increases the breadth of biological control.
Some of the new companies supplying biological control agents are oriented
towards the production and sale of long recognized biological control agents,
such as Bacillus thuringiensis Berliner and Trichogramma spp. Other
companies search for new agents and modify existing agents by genetic
engineering (Anonymous 1985a, 1985c, 1985d, 1986, 1987, Hussey 1985, Perkins
& Garcia 1999). Microbial agents now take less than 1% of the worlds's
pesticide market (Anonymous 1985c), but interest shown by new companies
suggests a bright future. Three new areas of study have increased the scope of biological
control research. In 1960 biological control research was almost entirely
confined to the use of insects to control insect pests and, in a few cases,
to control noxious plants. The methods used were largely those of classical
biological control: foreign exploration for exotic natural enemies,
importation of natural enemies, and release in the field followed by
evaluation. A few useful cases were known of the uses of pathogens to combat
noxious plants (Andrés et al. 1976) and animal species (Weiser et al. 1976).
Additionally, work before World War II had demonstrated the utility of
indigenous natural enemies. Rudimentary ideas began to emerge during the
1930's and 1940's concerning the need to use insecticides in ways that would
not interfere with the suppressive power of insect natural enemies.
Nevertheless, the field of biological control was largely classical and
research was oriented toward finding new natural enemies that would provide
dramatic suppression of a pest comparable to that shown by the Vedalia beetle
against the cottony cushion scale. At least three new areas of research have developed since the
1950's: biological control of plant pathogens, use of pathogens for the suppression
of weeds and insects, and integrated pest management (IPM). Plant pathogens
to control weeds are an active area of research. A landmark monograph on the
subject was published (Charudattan & Walker 1982), which unites the study
of plant pathology, weed science and plant physiology. There were 55 projects
cited involving the use of pathogens, including bacteria, fungi, nematodes
and viruses. Five of these projects were considered operational. Control of
skeleton weed in Australia by the rust fungus, Puccinia chondrillina
Bubak & Syd, from the Mediterranean area, returned an estimated annual
savings of $25.96 million. Water hyacinth control by Cercospora rodmanii
Conway reached the stage of pilot tests by the United States Corps of
Engineers in 1982. A second new field is the use of biological control for the
control of plant pathogens. A recent work by Cook & Baker (1983) noted
that 20 years earlier only three examples of the use of antagonistic
organisms to control plant pathogens could be cited, and 10 years earlier
only six examples could be cited and only two were used commercially. The
1983 monograph had 1,081 references, 60% of which were post-1974. At the time
of publication Cook & Baker had 15 key examples of successful
applications of biological control of plant pathogens that could be
illustrated in detail. The expansion of biological control into the field of
plant pathology represents a new arena for biological control. Integrated pest management which heavily involves biological
control, is a promising approach. IPM as a pest control strategy was
profoundly influenced by classical biological control (Perkins 1982), but it
is doubtful that IPM's roots helped encourage research in biological control
between 1960-1980. The U. S. National Science Foundation removed classical
biological control from the large research project, "The Principles,
Strategies and Tactics of Pest Population Regulation and Control in Major
Crop Ecosystems," in favor of research on the ecological theory of why
and how biological control works (Huffaker 1985). Thus, the first major
research effort in IPM was handicapped by not building one of the component
techniques for pest suppression into the basic design of the new research.
Systems analysis and computer modeling were favored instead. Combining biological control with pesticide use was the
cornerstone on which the concept of integrated control was founded (Perkins
1982), but later definitions of IPM obscured the importance of biological
control. The current definition of IPM does not mention biological control,
or any other specific control technology explicitly: "Integrated pest
control is a pest population management system that utilizes all suitable
techniques in a compatible manner to reduce pest populations and maintain
them at levels below those causing economic injury. Integrated control
achieves this ideal by harmonizing techniques in an organized way, by making
control practices compatible, and by blending them in a multi-faceted,
flexible, evolving system;" (Smith & Reynolds 1967, Frisbie &
Adkisson 1985). In recent years, researchers have begun to ask whether biological
control ought to be seen as fundamental to IPM, and to receive the funding
levels appropriate to such a critically important technology. Some of these
researchers believe biological control is fundament al to IPM but funding for
biological control research is less than 20% of the total given to IPM. Most
funds support pesticide timing, modeling of plant/pest interactions, defining
the economic threshold, and predicting the size of pest populations (Hoy
& Herzog 1985). Work on biological control must be built into IPM
research from the beginning if biological control practice is to be
successful. Tauber et al. (1985)
state, "In many, if not most cases, biological control by itself, does
not provide economically acceptable pest suppression in agricultural cropping
systems. Therefore, biological control must be developed and implemented as a
component of IPM. However, if it is to be an integral part of IPM (along with
plant resistance, cultural methods and pesticidal controls) biological
control must be nurtured to become a strong vital entity." Important Factors Affecting
Research in Biological Control.--There are many indications that biological control research of
the mid to late 1980's is healthy and vibrant. Such indicators suggest that
whatever factors govern the research in biological control, they are moving
in favor of biological control. Complex social phenomena are impossible to
attribute precisely to clear causes, but several seem particularly relevant
since the early 1980's. Some arise from events removed from the activities of
the biological control workers, but others are due to the activities of the
research community. Scientific research requires resources, so it is not surprising
that the amount of research in biological control is highly correlated with
the gross domestic product (GDP) of a country. Perkins & Garcia (1999)
presents the GDP of 58 countries, each of which produced at least one paper
in biological control, of which an abstract was published during the 1984-86
period. The data suggests that countries with an annual GDP of $10 billion
will publish about 9.5 papers in biological control every three years, or 3.2
papers per year. Alternatively, for $2.3 billion of annual GDP, it would be
expected to see one paper in biological control published each year.
Productivity of research in biological control correlated with GDP indicates
that this form of research is similar to others in the sense that wealthy
countries do more of it. Correlation between a country's wealth and its
research productivity does not, however, reveal everything about the ways in
which each country may decide how much and what kind of biological control
research to perform. Moreover, the data suggest that some countries are
particularly high in their productivity of biological control research given
their GDPs (e.g., Canada, Australia and India), while others may be low in
output compared to their GDP's (e.g., Japan, Germany and France). Explanations for why some countries are high producers compared
to others are not obvious, but one possibility is that membership in an
international network such as CIBC is conducive to productivity in biological
control research. Therefore, countries such as Australia, India and Canada,
all long term members of Commonwealth Institute of Biological Control, are
comparatively high. Conversely, countries that are not in coordinated
networks may have research productivities considerably below what the sizes
of their economies might suggest. France and Japan have GDP's 2.5 and 4.4
times the size of Canada's GDP, respectively, but these two countries have
research outputs of 0.67 and 0.79 the size of Canada's respectively. Canada's
membership in CIBC may be the cause of its higher research output (Perkins
& Garcia 1999). Another possibility to explain high interest in biological
control in countries like Canada and Australia is that both areas were
subject to European invasion. European people brought their insect and weed
pests (Crosby 1986). Much biological control work in these areas has been an
effort to reassociate imported pests with natural enemies. Europe, in
contrast, has had fewer invasive pests and therefore may be an area where
classical biological control has less success (Perkins & Garcia 1999). Environmental concerns about pollution potential from pesticides
or from the failure of chemical control through resistance and destruction of
natural enemies may also affect research allocations for biological control.
Malaysia has recently shown interest in biological control for conservation
purposes, despite some anxiety about introducing exotic pests (Perkins &
Garcia 1999). Other positive experiences with integrated pest management in
Malaysia nevertheless date to the 1960's (Conway 1972). Similarly Indonesia
has an official government policy to encourage implementation of IPM and
conservatory biological control, due to concerns about insecticide-induced outbreaks
of the brown plant hopper on rice. Problems with shortage of foreign exchange
to import chemicals has also been a factor in Indonesia and elsewhere
(England 1987, Repetto 1985, Perkins & Garcia 1999). Interest in environmental protection has created barriers to
research in biological control. Ecologists and the public realize that the
introduction of any new agent, even beneficial, can have undesirable
outcomes. Capabilities of producing genetically engineered agents have
complicated this issue further. Consequently biological control researchers
must now contend with regulations from which they were previously exempt,
such as the Endangered Species Act, the National Environmental Protection
Act, and the Federal Food, Drug and Cosmetic Act (Coulson & Soper 1992,
Waage & Greathead 1987). The
Political Economy of Biological Control Research & Research
Needs Studies are required to determine how social and economic factors
affect the allocation of resources to biological control. Factors likely to
be of importance are the philosophical world views prevalent in the research
community, the political strength and organization of agriculturalists, the
nature and size of the agricultural economy, the research activities of
neighboring countries and the political currents favoring environmental
protection. Judd et al. (1987) analyzed socio-economic factors determining research
investments in agricultural science, but it is not possible to make
predictions about the factors affecting research in biological control. An examination of the agricultural research establishment of each
country could indicate ways in which biological control research could be
enhanced, given the specifics of the individual country. Factors affecting
research, both positive and negative, need analysis on a country-by-country
basis. Recent events offer challenges to increasing research in biological
control, particularly on weeds. The basic conflict is that one person's weed
may be another's valuable crop plant. To illustrate this, Australian court
injunctions recently blocked the importation of insect control agents for the
plant Echium plantegineum (L.). Livestock
interests know E. plantagineum as
"Patterson's Curse," but beekeepers call it "Salvation
Jane." The popular names imply strongly differing attitudes toward the
plant (Waage & Greathead 1987). A commercial biological control industry based on release of
mass-produced pathogens, parasitoids and predators, indicates other factors
may be important in the future: patents, taxes, commercial policies and laws.
Countries encouraging the entrepreneurship of biological control
manufacturers, through policies favorable to their enterprises or through
direct subsidies, may find that the manufacturers make significant additions
to research in biological control. Socio-Economics
of Biological Control Investment.--There is a
problem which stems from the fact that the actual or potential users of
biological control products number in the hundreds of millions of
individuals, including all the farmers of the world and other decision makers
who have responsibilities for protecting society from pests. The research
community in contrast is small with numbers limited to a few thousand
individuals. Furthermore, researchers deliberately leave a trace of their
activities via publication, but farmers and pest control decision makers
usually leave no written record of their actions, certainly not a publica
record that is easily accessible for review. Pest control decisions are also complex, and are made for the
private benefit of the decision makers. Some, however, are made by officials
in public agencies for the public benefit. Therefore the social and economic
factors affecting the choices made by the decision maker are complicated by
the nature of the institution in which the decision maker works. Another
complication in assessing the degree of implementation in biological control
emerges from the complexity of the technology. Each of the three categories
of biological control (classical, augmentative, conservatory) will probably
have different factors affecting their respective implementations. A theoretical model of the relevant social and economic factors
may be constructed. The most useful perspective on the subject begins with
the recognition that if someone decides to use biological control, then he
has chosen a particular technology to achieve specific material ends. The
choice is made in the context of alternatives ranging from doing nothing to
selection of another way of mitigating the damage from the pest. A conscious
decision to adopt biological control is an investment decision, i.e., an
action based on choice in which the decision maker expects a return,
presumably a return that is better than could be expected from other
technology choices. The return could be monetary or have a high monetary
component. Nonmonetized and nonmaterial returns could also be important to
the decision maker. When use of biological control is perceived as an investment
decision, the factors affecting the use of the three categories of biological
control appear different in terms of the risks accepted by the decision
maker. Classical biological control is the lest problematic for the
researcher and the farmer or public. If an introduced exotic control agent
has been screened for adverse properties, the only monetary risks involved
are the costs for exploration, shipment, quarantine and release. If the
organism succeeds in its new context, then most likely it will return
substantial rewards over a period of years for a relatively small investment.
Moreover, most classical biological control is conducted by the state, so the
individual pest control decision maker bears no personal financial risk. In
many cases the individual grower may not be consulted about the decision to release
an exotic agent because the research community bears full responsibility and
power to identify pests, seek solutions and implement them as part of a
research implementation program. The activities are all research until the
introduced organism demonstrates its effectiveness. DeBach (1974) and Coulson
& Soper (1991) argued that the returns from this sort of biological
control research and development have been extraordinarily high compared to
the amounts spent on biological control research, including expenses for
those introductions that resulted in no significant suppression of the pest. Classical Biological Control.--The close
relationship between classical biological control and the research enterprise
makes the factors affecting implementation of classical biological control
likely to be identical to those affecting biological control research
generally. The larger the economy the more likelihood that classical
biological control research and implementation will be accomplished. However,
size of the economy cannot be the sole determinant of the efforts invested in
classical biological control. Decisions within the research community could
lead to resources going into augmentative or conservatory biological control
research rather than classical. Additionally, classical biological control
requires either foreign exploration or collaboration with foreign scientists
who agree to ship exotic organisms. Political relationships between countries
therefore can influence the fortunes of classical biological control
research. Augmentative Biological Control.--Practical schemes for artificially releasing a large number of
controlling organisms to attack a pest are inevitably dependent on the scale of
industrial culture of the controlling organism. The agents are packaged, sold
and dispersed much as a pesticide produce. Factors affecting use of such a
produce are not different from those affecting the use of a pesticide: cost,
ease of use, effectiveness, safety and ability of the agent to integrate
easily with other parts of the operation. Conservation.--The preservation of natural enemies present in the environment
is a problematic investment from the viewpoint of the individual pest control
decision maker. Perhaps the difficulties can best be explained by reference
to a typical situation in IPM. A natural enemy present in the farmer's fields
provides less suppression of a pest because pesticides or cultural practices
destroy or otherwise disfavor expression of the natural enemies. If the
grower would alter existing practices the natural enemy population might
provide a higher level of suppression of the pest, perhaps enough to obviate
the need for other pest control measures. Two events must occur to make use
of the existing natural enemy complexes. First, the grower must stop
destroying the effectiveness of the existing natural enemies. Unfortunately,
alteration of existing practices may open the grower's entire mode of
operation of risk or loss or severe disruption. Ending the use of a
pesticide, for example, could expose the grower to losses from a pest which
might be prevented by the preserved natural enemies. Therefore, the grower
must have confidence that the foregone practice will not result in devastating
losses. Secondly, the grower must monitor the pest and natural enemy
populations to ensure the pests are suppressed. Some studies have examined the inclinations and abilities of
farmers to adopt IPM schemes, most of which have a component of conserving
natural enemies (Wearing 1988). Peanut farmers in Georgia evidence reluctance
to shift to IPM despite objective data indicating that the new technology was
more efficient than conventional pest control (Musser et al. 1986). Georgia
cotton growers received no increase in net returns from IPM (Hatcher et al.
1984), so the attractiveness of this technology for them was slight. Adoption
of IPM by Iowa growers was related to opinion leadership an adoption
orientation, and prior knowledge of IPM. In turn, these variables were
positively related to income, education, farm size, and attitudes towards
chemicals (Salama 1983). One citrus grove manner in California reported
having saved $500-600/ha. by using IPM rather than chemicals alone (Hardison
1986). He reduced pest control costs from 35-40% and cash production costs to
8% Marking studies have shown that lady beetles, lacewings, syrphid flies and parasitic wasps
fed on nectar or pollen provided by borders of flowering plants around farms.
Many insects were shown to have moved 250 ft. into adjacent field crops. The
use of elemental marker rubium also showed that syrphid flies, parasitic
wasps and lacewings fed on flowering cover crops in orchards and that some
moved 6 ft. high in the tree canopy and 100 fleet away from the treated area.
The use of nectar or pollen by beneficial insects helps them to survive and
reproduce. Thus, planting flowering plants and perennial grasses around farms
may lead to better biological control of pests in nearby crops (Long et al.
1998). Risks for adopting conservatory biological control may be
particularly high when the crop's price depends on cosmetic quality. Fenmore
& Norton (1985) analyzed the economics of the production of English
dessert apples and the potentials for adopting conservatory biological
control rather than calendar-based chemical applications. They concluded that
the recent price history of these apples is such that a farmer would be
taking a grave risk to switch from automatic sprays to IPM. As little as a 1-2%
shift of the crop from cosmetically perfect to damaged but usable fruit would
be sufficient to eliminate all savings of the costs of insecticides obtained
from IPM practices. This case study exemplifies the concept that pesticides
provide cheap insurance against catastrophic economic losses, even when an
argument can be made that the chemicals are not needed on biological grounds. Crops that are not heavily dependent upon cosmetic quality may be
better candidates for conservatory biological control. Masud & Lacewell
(1985) analyzed adoptions of IPM in southern and southeastern United States
cotton production. They concluded that various alterations in production
practices, including IPM, could reduce insecticide use and produce
significant savings at an acceptable level of risk. Burrows (1983) also
concluded that IPM could reduce pesticide use in California cotton production
by 31%. These examples do not necessarily mean that biological control
will have little utility on crops in which cosmetic quality is important.
Examples from many countries demonstrate the success of biological control,
usually classical, in fruits such as citrus, apples and olives (Huffaker
& Messenger 1976, Hardison 1986). The critical factor may lie in the
notion that if biological control is extremely effective, then it may be
readily adopted. Cases in which the natural enemy is not as effective so that
management is still required by the grower, may be more difficult to adopt.
Entomological researchers may correctly argue that suppressive power is
available from the natural enemy, but a grower less skilled in entomology and
dependent upon each year's crop for his livelihood, will see the situation
differently. Alternatively, biological control may be useful on crops in
which cosmetic quality is important provided the pest does not attack the
marketed portion of the plant directly (Perkins & Garcia 1999). Under some circumstances factors transcending the individual
decision maker may become of paramount importance. The attitudes and
knowledge of the individual pest control decision maker may be immaterial to
the ability of a particular biological control technology to function.
examples of these transcendent considerations include how the pest control
decision makers are organized and relate to each other and to their
supporting scientists; the relationships between the decision makers and the
authority of the state; and the nature of the market for the decision maker's
produce. Swezey & Daxi (1983) argued that little headway could be made on
the development of IPM practices for Nicaraguan cotton until after the Samoza
government was overthrown in 1979. Earlier the political and economic
structures of Nicaragua were conducive to overuse of pesticides. The effectiveness of an IPM scheme may depend upon cooperation
among farmers. When some farmers spray insecticides, the drift may destroy
the natural enemies being conserved by other farmers. Under such
circumstances an individual grower would be powerless to adopt biological
control without convincing all growers in the area that they, too, should
conserve their natural enemies by not spraying. This situation is probably
well illustrated in the lower San Joaquin Valley of California where diverse
cropping systems intermingle, and spray drift is a widespread occurrence. Collaboration between growers may be more difficult to achieve
than convincing individual growers to conserve their natural enemies. An
apparently simple question of technological choice by a farmer may be a more
complicated matter involving the question of social and political
relationships among growers in a particular region. Habitat Alteration.-- A notable case is the successful habitat reduction for houseflies
that breed in decaying melons in the American Southwest (Legner & Olton 1975, Olton & Legner 1973). The simple procedure of breaking-open
culled melons at harvest accelerated decay of the breeding source and greatly
reduced fly breeding. Another example
is the elimination of breeding sites for the Australian bush fly, Musca
sorbens, in the Marshall Islands by reducing the number of unleashed dogs
on the islands as well as the institution of an effective adult fly baiting
procedure (Legner
et al 1974. ) Pest Managment Conflicts -- See Discussion Perkins and Garcia (1999) concluded that biological control has a
place in the most modern and sophisticated of pest control technologies, but
researchers and advocates of the technology must be sensitive to the factors
working against an easy transition to more reliance on biological control.
Failure to be realistic about the social and economic factors weighing
against use of biological control might actually be detrimental to the
research enterprise. Despite the problems, several biological and cultural trends
could improve biological control technology. An understanding of these trends
could promote research and use of biological control in many areas of the
world. Biological considerations of importance to biological control
include problems associated with the use of pesticides, particularly
insecticides: resistance, destruction of natural enemies accompanied by pest
outbreaks, and damage to the health of humans and nontarget organisms. Rachel
Carson's Silent Spring (Carson 1962) presented the first
analysis of these problems, but many policy studies since her landmark work
have confirmed the accuracy of her thoughts. Pesticide resistance and destruction of natural enemies make
chemicals technologically ineffective for the pest controller, thus providing
an incentive to look elsewhere for relief from pest damages. Harm to
non-target organisms leads to more stringent regulations, which places the
pest controller under severe political pressure to find an alternative. In
either case the biological control researcher can find an opportunity to
provide a less dangerous mode of pest control, and the client audience of
pest controllers will be a willing audience. Cultural factors affecting the
fortunes of biological control are more complex than the biological considerations.
The most important trends can be grouped into two main categories: regulatory
and pricing. REFERENCES: [Additional references may be found at
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Resources Ltd. in UK. Biocontrol News & Info. 6(4): 298-99. Anonymous. 1985c. Editorial. Biocontrol News & Info. 6(2):
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