tailieunhanh - Insect Ecology - An Ecosystem Approach 2nd ed - Chapter 3

3 Resource Acquisition ALL ORGANISMS ARE EXAMPLES OF NEGATIVE ENTROPY, IN CONTRAST TO the tendency for energy to be dissipated, according to the Second Law of Thermodynamics. Organisms acquire energy to collect resources and synthesize the organic molecules that are the basis for life processes, growth, and reproduction. | 3 Resource Acquisition I. Resource Quality A. Resource Requirements B. Variation in Food Quality C. Plant Chemical Defenses D. Arthropod Defenses E. Factors Affecting Expression of Defenses F. Mechanisms for Exploiting Variable Resources II. Resource Acceptability III. Resource Availability A. Foraging Strategies B. Orientation C. Learning IV. Summary ALL ORGANISMS ARE EXAMPLES OF NEGATIVE ENTROPY IN CONTRAST TO the tendency for energy to be dissipated according to the Second Law of Thermodynamics. Organisms acquire energy to collect resources and synthesize the organic molecules that are the basis for life processes growth and reproduction. Hence the acquisition and concentration of energy and matter are necessary goals of all organisms and largely determine individual fitness. Insects like other animals are heterotrophic . they must acquire their energy and material resources from other organisms see Chapter 11 . As a group insects exploit a wide range of resources including plant animal and detrital material but individual organisms must find and acquire more limited appropriate resources to support growth maintenance and reproduction. The organic resources used by insects vary widely in quality nutritional value acceptability preference ranking given choices and tradeoffs and availability density and ease of detection by insects depending on environmental conditions. Physiological and behavioral mechanisms for evaluating and acquiring food resources and their efficiencies under different developmental and environmental conditions are the focus of this chapter. I. RESOURCE QUALITY Resource quality is the net energy and nutrient value of food resources after accounting for an individual s ability and energetic or nutrient cost to digest the resource. The energy and nutrient value of organic molecules is a product of the number elemental composition and bonding energy of constituent atoms. 53 54 3. RESOURCE ACQUISITION However organic resources are not equally