Parthenium Weed (Parthenium hysterophorus L.) Research in Ethiopia: Impacts on Food Production, Plant Biodiversity and Human Health

The highly competitive, adaptable and allergenic weed Parthenium hysterophorus (Composite) is an invasive annual weed believed to be introduced to Ethiopia in 1970s. Field surveys, plant biodiversity impacts, and analysis of secondary plant compounds in P. hysterophorus and its possible impact on human health have been studied in Ethiopia since 1998. The weed has invaded a variety of habitats ranging from roadsides to grasslands and crop fields. Infestations were found to be greater than 20 plants per m2 and yield losses in sorghum reached 46-97% depending on the location and year. In grasslands dominated by parthenium, native plant species composition and abundance was found to be low. Manual control of parthenium by farmers resulted in the development of skin allergies, itching, fever, and asthma. These reactions could be attributed to the presence of secondary plant compounds (parthenin, chlorogenic acid, isocholorogenic acid, vanilic acid and caffeic acid) which were found in parthenium with significant variation in their concentrations among the different plant parts, dependent on plant locality, moisture content and plant size. The social cost of parthenium in Ethiopia was measured by Disability Adjusted Life Years and its equivalence in terms of monetary value was estimated at US$ 2,535,887 - 4,365,057. More resources have to be invested to tackle the parthenium problem as the estimated loss is disproportionate to the cost of investment in parthenium research and development activities.

极具竞争力、适应性强且具有致敏性的入侵性一年生杂草钻形银胶菊（Parthenium hysterophorus，菊科（Composite））被认为于20世纪70年代传入埃塞俄比亚。自1998年起，埃塞俄比亚便针对该杂草开展了野外调查、植物生物多样性影响研究，以及对其体内次生植物化合物的分析，并探究了其对人类健康的潜在影响。该杂草已入侵多种生境，涵盖路边、草地乃至农田。调查显示，其种群密度可达每平方米20株以上，受侵染的高粱产量损失率因地域与年份差异可达46%至97%。在以钻形银胶菊为优势种的草地中，本土植物的物种组成与丰度均处于较低水平。农户通过人工方式防治钻形银胶菊时，常出现皮肤过敏、瘙痒、发热及哮喘等不良反应。此类反应可归因于该杂草体内含有的次生植物化合物：银胶菊素（parthenin）、绿原酸（chlorogenic acid）、异绿原酸（isocholorogenic acid）、香草酸（vanilic acid）以及咖啡酸（caffeic acid）。研究发现，这些化合物在植株不同部位的含量存在显著差异，且受植株生长地域、水分含量及植株大小的影响。埃塞俄比亚境内钻形银胶菊造成的社会成本以伤残调整寿命年（Disability Adjusted Life Years）进行核算，其等效货币价值估算为2535887至4365057美元。鉴于估算的损失与针对该杂草的研发投入严重不成比例，需投入更多资源以解决钻形银胶菊带来的入侵问题。