臺南水雉農藥中毒原因分析

An analysis on pheasant-tailed jacana pesticide poisoning in Tainan, Taiwan

農藥為農業中很重要的農作物保護資材，然而不當的使用卻可能對生態環境和非目標生物造成危害。農藥對野生動物影響可分成直接毒害和間接傷害，而直接毒害又可細分成蓄意和非蓄意傷害。殺蟲劑加保扶過去常被違法用於毒殺鳥類以減少農作物損害，本研究即針對於2017年1月1日禁用高含量加保扶成品農藥前後，間隔8年之野生鳥類農藥中毒事件調查來分析特定農藥風險減輕措施之成效。特有生物研究保育中心分別於2014年及2022年接獲臺南地區15隻及16隻的水雉疑似農藥中毒通報事件。經解剖，於水雉砂囊中均觀察到未消化之去殼米粒及穀粒，採集胃內容物樣本送至農業藥物毒物試驗所進行農藥殘留分析。結果顯示於2014年來自三處不同農地樣品各送驗1隻，3隻胃內容物均驗出農藥加保扶（0.55-165.00 ppm），其中2隻亦分別驗出得克利（0.11 ppm）及福瑞松（1.80 ppm）；於2022年之16隻疑似中毒檢體全部送驗，共驗出13種農藥，其中12隻均驗出高濃度加保扶（1.41-115.22 ppm），其餘4隻中有3隻驗出托福松（8.39-61.64 ppm）。前述加保扶為鳥類劇毒藥物且驗出濃度大都在致死劑量。此外，在屍體附近發現之穀粒誘餌亦有高含量加保扶（1159.24 ppm）顯示此為故意毒殺事件。由此兩年度發生之水雉加保扶中毒事件顯示，加保扶的不當使用並未因2017年加保扶40.64%水懸劑、44%水懸劑和37.5%水溶性袋裝可濕性粉劑的禁用而遏止，建議有關權責機構應加強風險減輕措施防止野生動物農藥中毒再次發生。

Chemical pesticides are essential for plant protection and ensuring crop productivity. However, inappropriate pesticide use could adversely impact ecosystems and non-target organisms. Pesticides can directly or indirectly cause wildlife death, in which the direct hazards could include negligence or intentional behavior. Carbofuran, an insecticide, was illegally used in the past to minimize crop damage by birds. This study examined two events of pesticide poisoning of wild birds within a span of eight years, occurring before and after the ban of pesticides containing high amounts of carbofuran on January 1, 2017, so as to analyze the effectiveness of the mitigation measures for specific pesticides. The Wildlife Rescue and Research Center of the Endemic Species Research Institute of Taiwan received 15 and 16 cases of suspected pheasant-tailed jacana (Hydrophasianus chirurgus) poisoning in 2014 and 2022, respectively. Autopsies revealed that most of the gizzards of the dead jacana contained undigested grains. Samples of these grains and gizzard tissue were analyzed for pesticide residue by the Taiwan Agricultural Chemicals and Toxic Substances Research Institute. Three samples in 2014 from different farmlands were analyzed, all found to contain high concentrations of carbofuran (0.55-165.00 ppm), and two of which were found with tebuconazole (0.11 ppm) and phorate (1.80 ppm). Moreover, 13 pesticides were detected out in all the 16 samples in 2022, 12 of which contained high concentrations of carbofuran (1.41-115.22 ppm), while three of the other four samples contained terbufos (8.39-61.64 ppm). Carbofuran is highly toxic to birds, and the detected concentrations are mostly lethal doses. Finally, baits with a lethal concentration of carbofuran (1159.24 ppm) were found near the corpses’locations, indicating that these poisoning events could be a consequence of intentional behavior. In summary, the wild bird poisoning events in 2014 and 2022 implied that the partial ban on highly-concentrated carbofuran formulations (including 40.64% and 44% carbofuran suspension concentrate as well as 37.5% carbofuran wettable powder in water soluble bag) in 2017 had failed to prevent its misuse. We urge the regulatory authorities to strengthen their risk mitigation measures to prevent further incidents of pesticide poisoning in wildlife.