一、综合治理的基本原理 (一)害虫综合治理的基本原理 控制园艺生态系中生物群落的物种组成,尽可能减 少园艺生态系中害虫的种类,增加有益生物的种类。 控制害虫种群数量,对已有害虫采用适当的方法, 压低害虫的种群基数、恶化其生存繁殖环境,或直接消 灭害虫。 控制害虫危害,在适于某种害虫大发生的地域种植 不适于其取食危害的作物或作物品种,调整作物播种期, 使作物易受为害造成经济损失的敏感期错开害虫发生期

Chapter 7 develops the concept of efficiency and explores why many tasks are best left up to the market It presents the concept of economic surplus in detail and looks at how unregulated markets can generate the largest possible economic surplus Chapter 7: Efficiency and Exchange

Chapter 6 presents the supply side of the market using an approach parallel to that of the demand side of the market in Chapter 5. The chapter presents the material in a way that illustrates the second core principle of the textbook, that marginal benefits should equal marginal costs Chapter 5 presents the demand curve as derived from marginal benefit and Chapter 6 presents the supply curve as derived from marginal costs

1. Which of the following explains why automobile engines are smaller in England than in the united states?

1. To say that someone needs a good is to suggest that he cannot choose to do without the good or buy a substitute for it. We are more likely to be mindful of the fact that almost all goods have substitutes if we speak of wants rather than needs 2. Even though we cannot actually

1. Price changes affect quantity demanded for two reasons: They attractiveness of substitute goods and they alter the real value of the consumers purchasing power. The second effect grows larger as the share of the consumers

Chapter 3 introduces markets and provides an overview of the supply and demand model. It begins by comparing central planning and the market as alternative methods of allocating resources Chapter 3-Supply and Demand: An Introduction Slide 3

Multiple Choice If one person can perform a task in fewer hours than another, you know the person has in performing the task. a. an absolute advantage. b. a comparative advantage. C. both a comparative advantage and an absolute advantage. rd. neither an absolute nor a comparativ advantage

An individual has a comparative advantage in the production of a particular good if she can produce it at a lower opportunity cost than other individuals. An individual has an absolute advantage in the production of a good if she can produce more of that good than another individual. using comparable amounts of time. raw materials and effort

Answers to Review Questions 1. Your friend probably means that your tennis game will improve faster if you take solo private lessons instead of group lessons. But private lessons are also more costly than group lessons. So those people who don' t care that much about ho rapidly they improve may do better to take group lessons and spend what they save on other things