摘要
在害虫研究与防治中,一个基本的问题是:多少为害引起的作物损失抵得上防治代价?多大密度的害虫能造成如此为害?一般认为经济阈值(economic threshold,简称ET)能回答这类问题,因此它是现代害虫防治的基本决策依据,也是当今经济昆虫学和害虫防治中谈论得最多的问题(Pitre等,1979;Gutizrrez等,1984;Pedigo等,1986)。然而,目前国内外文献中ET的概念模糊、定义繁多、技术零散、争论激烈而持久,缺乏较为系统的探讨与清理,给研究、教学及应用带来很大不便;笔者在棉铃虫ET研究中,处理了从田间试验到一般理论的整个问题,发展了ET的理论与技术。结合广泛的文献资料,本文试对ET研究在各方面的进展作一剖析,提出个人见解,其内容包括概念,定义、
This paper gives an overview on the studies and conceptual development of economic chres-hold (ET) for insect pest control. Examinations are made on the definitions, models and techniques of ET. From the original theory of Stern et al (1959) the definition of ET now widely accepted denotes 'the density at which control measures should be determined to prevent an increasing pest population from reaching the economic injury level (EIL)', and E1L means 'the lowest population density that will cause eccnomic damage'. Though being simple these definitions are considered to be deficient in several respects. Firstly, EIL is defined with pest population density which may not coincide with the real level of injury or degree of pest feeding on the crop. Secondly, the term economic damage is also ambiguous because it can be used to refer to crop loss manifested in the decrease of harvest as compared with that not injured or it includes control cost and thus equals ET. Furthermore, in natural condition the pest population is not necessarily increasing because of the infleunce of an array of biotic and abiotic factors from the enviroment. It does not make sense to say that a control measure should be taken when a pest population reaches the level of ET to prevent the population from reaching EIL. Some workers think that a pest population is apt to be treated before EIL is reached when the population is in a stage susceptible to the treatment. This action may not be appropriate because ET should be determined in this stage otherwise how early before EIL to initiate a control measure becomes-itself a threshold problem. Another group of workers regard that ET and EIL are respective population densities at sampling and treatment. This is not generally useful because treatment can be carried out right after sampling. In this context evidence is provided to indicate that the definition held by entomologists is identical to that by agro-economists, showing that the crop loss saved does not equal to control cost in the case of having crop over-compensation after pest injury. Based on the author's personal experience, discussions are made on decision making in pest control in relation to ET and the optimal control and the significance and limitation of different types of ET models. Seven methods generally used in determining the relationship between crop loss and pest density are summarized with emphasis on the affecting factors from the environment, index reflecting crop's compensatory capacity and the direct and indirect benefits and costs from control actions. The outlook of the ET research in the near future is considered holistically in connection with the advances in the studies on the response of the crop after pest injury, the development of pest resistance towards insecticide, actions of natural enemies and environmental pollution as well as the effects of other pests and management decisions.
出处
《昆虫学报》
CAS
CSCD
北大核心
1989年第4期492-500,共9页
Acta Entomologica Sinica
关键词
经济阈值
害虫防治
作物损失
economic threshold--yie Id loss assessment--pest control
