Alternatives

Alternatives

The problems with traditional pest management by means of insecticides has its obvious drawbacks, including expense, ineffectiveness and damage to humans, animals and the environment. It is estimated that the share of crops lost due to insects has doubled in the last 40 years, while the amount and toxicity of insecticide used have increased nearly ten times. These shortcomings have recently forced researchers and farmers to search for alternative solutions. One such broad category of solutions is known as integrated pest management.

Integrated pest management can have a wide variety of meanings. In the most broad definition it is, "the optimization of pest control in an economically and ecologically sound manner, accomplished by the coordinated use of multiple tactics to assure stable crop production and to maintain pest damage below the economic injury level while minimizing hazards to humans, animals, plants, and the environment."¹ This can be broken down into two main categories: classical and comprehensive IPM.

Classical IPM

In classical (or restricted) IPM, pesticides are used only when the insect population exceeds a certain level. This technique requires careful monitoring of the pest population, and is thus often difficult to achieve successfully. However, it is hoped that additional technology will make this process simpler, and therefore more effective. New methods of pesticide application are also hoped to increase the efficiency of restricted IPM, since in some cases up to 75% of the chemical does not reach its intended target. Estimates of reduction in pesticide use under classical IPM systems vary widely, but are generally around 30-50%.

Comprehensive IPM

Comprehensive IPM essentially uses classical techniques in addition to a tremendous variety of other technologies in an attempt to control insect populations. These systems rely heavily on monitoring pest populations and movement, biological control by natural enemies, enhancing host-plant resistance, prediction of economic injury levels, and crop rotation, to name only a few. These most significant topics will be discussed below.

One significant problem in pesticide use is that commonly used chemical agents kill not only the insects attacking the plant, but the enemies of that insect as well. Recent efforts made to avoid this problem include research into selective pesticides as well as the breeding of pesticide-resistant natural enemies.

Another feature of IPM is host-plant resistance. Significant efforts have been put forth, especially in recent years, to isolate and identify genes in plants which increase their resistance to insect damage. It is hoped that by isolating the most effective of these R genes, plants may be bred in such a way as to enhance these capabilities.

IPM also includes ideas such as crop rotation and pest population monitoring. Data on insect population size and movement frequently can be an indicator of the best location to plant a certain crop in a certain season. This idea is difficult to implement mainly because of the large degree of specialization inherent in today’s farms.

Probably the most subtle but effective element of IPM is prediction of damage levels. It is impossible to eliminate all pest problems, so the best solution is often to examine several different solutions and attempt to predict which combinations minimize losses.

Economic Benefits

Realizing the economic benefits of integrated pest management is a fairly simple task. Each of the systems mentioned above requires substantial investment in terms of time, money and research. However, these are (for the most part) one time costs. Once these systems are implemented it is much more cost-effective to maintain them than to continue purchasing millions of kilograms of pesticides every year. Take the following example² :

Energy and economic inputs per hectare for conventional and modified IPM corn production systems

Conventional System Modified IPM System

Input	Quantity	10³ Kcal	$	Quantity	10³ Kcal	$
Labor (h)	10	7	50	12	9	60
Machinery (kg)	55	1485	91	45	1215	75
Fuel (L)	115	1255	38	70	764	23
N (kg)	152	3192	81	27	5591	17
P (kg)	75	473	53	34	214	17
K (kg)	96	240	26	15	38	4
Limestone (kg)	426	134	64	426	134	64
Corn seed (kg)	21	520	45	21	520	45
Cover crop seed (kg)	-	-	-	10	120	10
Insecticides (kg)	1.5	150	15	0	0	0
Herbicides (kg)	2	200	20	0	0	0
Electricity	100	100	8	100	100	8
Transport (kg)	322	89	32	140	39	14
Total		7845	523		3712	337
Yield (kg)	7000	24746		8100	29160
Output/input ratio		3.15			7.86

In this example the use of a modified IPM system not only decreased inputs, but increased output as well. This may seem like a single isolated case, but it is not. Data from similar IPM implementations in the U. S., Canada, and Western Europe show similar results, albeit not in all cases.

To fully understand the argument, economic effects on the environment must also be considered. Estimates of these effects are shown below³:

Costs	$ (millions per year)
Public health impacts	933
Domestic animal deaths and contamination	31
Loss of natural enemies	520
Cost of pesticide resistance	1400
Honey bee and pollination losses	320
Crop losses	959
Surface water monitoring	27
Grounwater contamination	1800
Fishery loses	56
Bird losses	2100
Gov't regulations to prevent damage	200

Total	8346

The total estimated environmental and social costs from pesticides in the United States is about $8.3 billion. This is hardly negligible, and is one of the main forces behind additional research into IPM.

Pesticides do in fact increase crop production. Current estimates put U. S. crop losses due to pests at 37%, equal to $50 billion⁴ . Without the use of pesticides and non-chemical controls, the numbers would rise to 63% and $90 billion⁵ . However, data from the last 40 years indicates that while pesticide use has increased dramatically, crop losses have not shown a consistent decline. Since integrated pest management systems often bring about higher crop yields at lower costs with reduced social and environmental damages, it is clearly the most effective method of meeting the exponential increase in world population and food demand.

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References ¹ Dover, M. J., A Better Mousetrap: Improving Pest Management for Agriculture, World Resources Institute, Washington, D. C., 1985
² Pimentel, D., Environmental and economic benefits of sustainable agriculture. In Paoletti, M. G. et al. (Eds) Socio-Economic and Policy Issues for Sustainable Farming Systems. Cooperativa Amicizia S.r.1., Padova, Italy, pp. 5-20.
³ USBC Statistical Abstract of the United States 1994. US Bureau of the Census, US Government Printing Office, Washington, DC.
⁴ Pimentel, D. et al, Environmental and economic impacts of reducing US agricultural pesticide use. In Pimentel, D. (Ed.) Handbook of Pest Management in Agriculture. Vol. I. 2nd edn. CRC Press, Boca Raton, pp. 679-718.
⁵ Oerke, E.C., et al, Crop Production and Crop Protection: Estimated Losses in Major Food and Cash Crops. Elsevier, Amsterdam.

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Last updated 9 November 1997.