Productivity of crops grown for human consumption is at risk due to the incidence of pests, especially weeds, pathogens and animal pests. Crop losses due to these harmful organisms can be substantial and may be prevented, or reduced, by crop protection measures. An overview is given on different types of crop losses as well as on various methods of pest control developed during the last century.Estimates on potential and actual losses despite the current crop protection practices are given for wheat, rice, maize, potatoes, soybeans, and cotton for the period 2001–03 on a regional basis (19 regions) as well as for the global total. Among crops, the total global potential loss due to pests varied from about 50% in wheat to more than 80% in cotton production. The responses are estimated as losses of 26–29% for soybean, wheat and cotton, and 31, 37 and 40% for maize, rice and potatoes, respectively. Overall, weeds produced the highest potential loss (34%), with animal pests and pathogens being less important (losses of 18 and 16%). The efficacy of crop protection was higher in cash crops than in food crops. Weed control can be managed mechanically or chemically, therefore worldwide efficacy was considerably higher than for the control of animal pests or diseases, which rely heavily on synthetic chemicals. Regional differences in efficacy are outlined. Despite a clear increase in pesticide use, crop losses have not significantly decreased during the last 40 years. However, pesticide use has enabled farmers to modify production systems and to increase crop productivity without sustaining the higher losses likely to occur from an increased susceptibility to the damaging effect of pests.The concept of integrated pest/crop management includes a threshold concept for the application of pest control measures and reduction in the amount/frequency of pesticides applied to an economically and ecologically acceptable level. Often minor crop losses are economically acceptable; however, an increase in crop productivity without adequate crop protection does not make sense, because an increase in attainable yields is often associated with an increased vulnerability to damage inflicted by pests.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/AD61661AD6D503577B3E73F2787FE7B2/S0021859605005708a.pdf/div-class-title-crop-losses-to-pests-div.pdf

Crop losses to pests

Twenty five years after its first enunciation, IPM is recognized as one of the most robust constructs to arise in the agricultural sciences during the second half of the twentieth century. The history of IPM, however, can be traced back to the late 1800s when ecology was identified as the foundation for scientific plant protection. That history, since the advent of modern organosynthetic pesticides, acquired elements of drama, intrigue, jealousy, and controversy that mark the path of many great scientific or technological achievements. Evolution of IPM followed multiple paths in several countries and reached beyond the confines of entomological sciences. Time and space constraints, however, bias this review toward entomology, among the plant protection sciences, and give it an obvious US slant, despite the global impact of IPM.

Integrated pest management: historical perspectives and contemporary developments.

The idea of using species-specific behavior-modifying chemicals for the management of noxious insects in agriculture, horticulture, forestry, stored products, and for insect vectors of diseases has been a driving ambition through five decades of pheromone research. Hundreds of pheromones and other semiochemicals have been discovered that are used to monitor the presence and abundance of insects and to protect plants and animals against insects. The estimated annual production of lures for monitoring and mass trapping is on the order of tens of millions, covering at least 10 million hectares. Insect populations are controlled by air permeation and attract-and-kill techniques on at least 1 million hectares. Here, we review the most important and widespread practical applications. Pheromones are increasingly efficient at low population densities, they do not adversely affect natural enemies, and they can, therefore, bring about a long-term reduction in insect populations that cannot be accomplished with conventional insecticides. A changing climate with higher growing season temperatures and altered rainfall patterns makes control of native and invasive insects an increasingly urgent challenge. Intensified insecticide use will not provide a solution, but pheromones and other semiochemicals instead can be implemented for sustainable area-wide management and will thus improve food security for a growing population. Given the scale of the challenges we face to mitigate the impacts of climate change, the time is right to intensify goal-oriented interdisciplinary research on semiochemicals, involving chemists, entomologists, and plant protection experts, in order to provide the urgently needed, and cost-effective technical solutions for sustainable insect management worldwide.

Sex pheromones and their impact on pest management.

The topic of economic decision levels probably is the most often-discussed issue in economic entomology and insect -pest management today. The fun­ damental questions addressed are: How many insects cause how much damage, and is the damage significant? Most entomologists agree that a common decision rule or threshold should answer such questions and that such decision rules are the backbone of progressive pest control (3, 46, 64, 79). At issue is the form such rules should take and how they should be developed. To date, the most widely accepted form is that of the economic threshold as presented by Stern et al (80). These authors developed their decision rule from basic principles of economic damage and the economic injury level (ElL), and it is from their ElL concept that much of our present theory is derived. The major advantage of this concept is its simplicity and practicality in most situations. The ElL, defined as "the lowest population density that will cause economic damage," has been used most often to support management decisions with short-range objectives, i.e. a one-season or less planning horizon at the farm level. Additionally, the concept has been applied primarily where man­ agement tactics are responsive rather than preventative. Consequently, ElLs have been most developed for occasional and perennial pests [sensu Stern et al (80)] where scouting, evaluation, and subsequent therapy are possible. ElLs have application for all pests, however, when used as criteria of management success. In this regard, they are as applicable to severe pests as to occasional pests and as applicable to preventative tactics as to curative ones. This is because most lPM strategies call for the reduction of pest populations to a level below that which is "economic;" i.e. the familiar principle of tolerating pest presence, albeit at noneconomic levels.

Economic Injury Levels in Theory and Practice

Background
Crops engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are planted on millions of hectares annually, reducing the use of conventional insecticides and suppressing pests. However, the evolution of resistance could cut short these benefits. A primary pest targeted by Bt maize in the United States is the western corn rootworm Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae).

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Robert van Den Bosch

Papers

The integrated control concept