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INTEGRATION OF OTHER PEST CONTROL METHODS

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.

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.

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.

REFERENCES:

Altieri, M. A. & D. K. Letourneau. 1999. Environmental management to enhance biological control in agroecosystems. In: Principles and Application of Biological Control. Academic Press, San Diego CA. 1046 p.

Elzen, G. W. & E. G. King. 1999. Periodic release and manipulation of natural enemies. In: Principles and Application of Biological Control. Academic Press, San Diego CA. 1046 p.

Johnson, M. W. & B. E. Tabashnik. 1999. Improving the use of chemicals: enchanced biological control through pesticide selectivity. In: Principles and Application of Biological Control. Academic Press, San Diego CA. 1046 p.

Schneider, F. 1939. Schadinsekten und ihre Bekämpfung in ostindischen Gambirkulturen. Separatabdruck aus der Schweitzer Zeitschrift für Forstwesen. Nr. 2 & 3.: 61-74.

Smith, R. F. 1969. Integrated control of insects: A challenge for scientists. Agric. Sci. Rev. 1969(1): 1-5.