有害生物對臺灣農業生態環境影響之經濟分析－以福壽螺、果實蠅為例

An Economic Analysis on the Impacts that Detrimental Organisms Cause to Taiwan’s Agricultural and Ecological Environment—The Cases of Pomacea canaliculatas and Fruit Flies

陳威廷(Wei-Ting Chen)

指導教授 ： 楊平世 ； 陳郁蕙

國立臺灣大學/生物資源暨農學院/農業經濟學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.00509

摘要

福壽螺(Pomacea canaliculata(Lamarck,1819))並非臺灣本地動物，於1979年由移民當地的華僑引入台灣，至今已成為國內典型的重要有害生物之一。果實蠅屬於國際上之重要檢疫害蟲，其疫病問題向來受到防疫相關單位的高度關注。過去國內在疫病蟲害方面的研究多半偏重於防治技術及檢疫技術層面，卻未將有害生物對農業生態環境所造成之影響從經濟學之角度加以估量。本研究利用條件評估法(Contingent Valuation Method, CVM)，衡量防治有害生物危害環境之經濟效益，從另一個角度來思考，其值亦為防治措施未妥善執行時，福壽螺、果實蠅危害農業生態環境可能造成的貨幣損失數目，該數值可提供未來農政單位於有害生物之防治措施、相關研究以及決策制訂時的參考。
過去與條件評估法相關之研究僅以與評價財貨有關的對象進行問卷調查，並無特別針對相關產業背景進行訪查的工作，參考資料相對上較為不足。因此本研究將分別從生產與消費兩個層面來瞭解有害種生物對台灣農業生態環境的影響，採用問卷調查的方式得知農民和一般民眾對福壽螺、果實蠅危害農作物的關注程度及意向。
由估計結果得知，在福壽螺危害防治的部分，受訪農民平均種植作物面積約為0.58公頃，每年每公頃投入防治福壽螺的金額平均約為2,133(元/年•公頃)，防治費用約占年所得的0.85%。若不採取任何防治措施，則每年每公頃平均損失約23,161元，平均損失率約為10.80%，而農民對於政府所推行防治福壽螺相關工作之綜合滿意程度約為26.21%。在果實蠅危害防治的部分，受訪的果農平均種植果樹面積約為0.98公頃，投入防治果實蠅的金額(包括農藥、套袋等費用)平均約為35,703(元/年•公頃)，防治費用約占年所得的7.31%。若不採取任何防治措施，則每年每公頃平均損失約271,608元，平均損失率約為38.82%，果農對於政府所推行防治果實蠅蟲害相關工作之綜合滿意程度則為43.46%。
在防治有害生物危害的願付價格分析部分，雙界二元選擇模型下根據適合度檢定得知，Weibull分配較能代表福壽螺防治願付價格之統計分配，中位數願付價格之平均數約為734(元/年•戶)，Log-normal分配較能代表果實蠅防治願付價格之統計分配，中位數願付價格之平均數約為579(元/年•戶)。由上述實證估計結果可進一步推估出防治福壽螺、果實蠅危害之總效益，其值分別為50.69億元與39.98億元，亦即民眾認為當防治措施沒有妥善執行時，福壽螺、果實蠅對台灣農業生態環境所造成之損失各為51億元、40億元新台幣。

關鍵字

福壽螺 ； 果實蠅 ； 經濟效益 ； 願付價格 ； 條件評估法

並列摘要

Pomacea canaliculatas(Lamarck,1819), which were introduced by overseas Chinese from South America in 1979, are not indigenous animals originated in Taiwan, but so far they have typically become one of the momentous detrimental organisms in this island. Fruit flies are pests of internationally significant importance, and all the time the problems that they cause have received close attention from the authorities concerned of preventing pests and diseases. In the past few decades, the studies with regard to pests and diseases in Taiwan laid particular stress on the aspects of preventive and quarantine techniques, with the result of neglecting to estimate the impacts that detrimental organisms cause to our agricultural and ecological environment from the viewpoints of Economics.
In this research, we make use of the Contingent Valuation Method (CVM) to appraise the economic benefits of guarding against detrimental organisms from damaging the environment, to think it over from another point of view, it is the amount of loss valued in monetary terms that Pomacea canaliculatas and fruit flies may bring about, under the conditions that precautionary measures were not properly implemented. The resulting figures of estimates are hopefully provided to the Council of Agriculture for the reference of preventing detrimental organisms, researches related, as well as policy decisions relevant to this issue to be made.
In the past, the researches applying contingent valuation methods were merely carried out by investigating the subjects with relation to the commodities being assessed, nevertheless they were not specifically aimed at inquiring about the information concerning the background of the industry, which resulted in the lack of reference materials. With a view to better understanding the impacts that detrimental organisms may cause to Taiwan’s agricultural and ecological environment, this research will be conducted from the production and consumption sides separately to examine the level of interests and inclinations through questionnaires that farmers and the public pay to the damage of crops causing by Pomacea canaliculatas and fruit flies.
On the part of preventing Pomacea canaliculatas, it is estimated that the average acreage of plants that the farmers cultivate is around 0.58 acres, and the amounts of money putting into preventing Pomacea canaliculatas every year is 2,133 NTD, which is about 0.85% of farmers’ annual income. Without taking any precautions, the average loss per year is about 23,161 NTD, and the average rate of loss is measured at 10.80%. The overall satisfaction ratio of performances valued by farmers that the government concerned set into action in preventing Pomacea canaliculatas is about 26.21%. Likewise, on the part of preventing fruit flies, it is estimated that the average acreage of plants that the farmers grow is in the neighborhood of 0.98 acres, and the amounts of money putting into preventing fruit flies every year is 35,703 NTD, which is about 7.31% of farmers’ annual income. Without taking any preventive measures, the average loss per year is about 271,608 NTD, and the average rate of loss is measured at 38.82%. The overall satisfaction ratio of performances valued by farmers that the government concerned set into action in preventing fruit flies is about 43.46%.
In the framework of double-bound dichotomous choice model for assessing the public’s willingness to pay for the prevention of detrimental organisms, we derive that the Weibull distribution best stands for the statistical distribution of WTP for preventing Pomacea canaliculatas, and the average median WTP is about 734 NTD per household, meanwhile, the Log-normal distribution best represents the statistical distribution of WTP for the prevention of fruit flies, and the average median WTP is approximately 579 NTD per household. From the results listed above, we are capable of inferring the total benefits of preventing Pomacea canaliculatas and fruit flies from damaging the crops and plants, which is about 5.07 billion and 4.00 billion NTD respectively. To put it differently, were the preventive measures not better taken, the amount of loss that Pomacea canaliculatas and fruit flies cause to Taiwan’s agricultural and ecological environment is about 5.1 billion and 4.0 billion NTD respectively.

並列關鍵字

Pomacea canaliculatas ； Fruit Flies ； Contingent Valuation Method (CVM) ； Willingness to Pay (WTP) ； Total Benefits

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