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INTEGRATION OF VARIOUS PEST CONTROL
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The Political Economy of Biocontrol Research & Research
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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. IX. Selective
Pesticides. 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. ------------------------------------------------------------------------------------------------------------------------------------------------- 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 which 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. Farming may
be controlled by individuals, partnerships, corporations, cooperatives or the
state; 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 data base 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 message 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 is 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 modelling 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, modelling 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 |