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

Advances in cowpea research , Advances in cowpea research , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Advances in cowpea research

The conflicting relationships between aphids and men: a review of aphid damage and control strategies.

Social insects have a tremendous economic and social impact on urban communities. The rapid urbanization of the world has dramatically increased the incidence of urban pests. Human commerce has resulted in the spread of urban invasive species worldwide such that various species are now common to many major urban centers. We aim to highlight those social behaviors that can be exploited to control these pests with the minimal use of pesticides. Their cryptic behavior often prohibits the direct treatment of colonies. However, foraging and recruitment are essential aspects of their social behavior and expose workers to traps, baits, and pesticide applications. The advent of new chemistries has revolutionized the pest management strategies used to control them. In recent years, there has been an increased environmental awareness, especially in the urban community. Advances in molecular and microbial agents promise additional tools in developing integrated pest management programs against social insects.

Managing Social Insects of Urban Importance

Mango anthracnose : Economic impact and current options for integrated management

strategy is better than another, according to specific, subjective criteria. The important point for the entomologist to note is that both positive and normative aspects of economics can be useful in assessing the performance of pest management activities and in making recommendations. Entomologists should also be aware that actual pest management decisions are based on normative considerations and therefore are subjective, no matter how carefully the costs and benefits have been assessed. Consequently, the economics of decision making in pest management is not just concerned with the dollars and cents of pest damage and control but with the goals and behavior of those who make pest management decisions.

G. A. Norton

Papers

Economics of Decision Making in Pest Management