Invasion and impacts of Xanthium strumarium in Borena Zone of Oromia Region, Ethiopia

An invasive alien species (IAS) is a species that is introduced from outside of its past or present natural range of distribution either by intentional or unintentional human activities. It may include gamete, seed, and egg of such species that might survive and subsequently reproduce. In addition to human related introduction mechanisms, extraordinary increase of wild species movement has been accelerating the rate of introduction, with deleterious consequences on native biodiversity[1]. In Ethiopia, IAS are posing major problems on native biodiversity including agricultural lands, rangelands, national parks, waterways, lakes, rivers, power dams, roadsides and urban green spaces with great economic and ecological consequences[2,3]. Like other countries in the tropics, hundreds of alien species has been introduced to Ethiopia. Some of these are IAS including Parthenium (Parthenium hysterophorus), Prosopis (Prosopis juliflora), water hyacinth (Eichhornia crassipes), cactus (Euphorbia stricta), Mimosa diplotricha, Xanthium strumarium (X. strumarium) and lantana weeds (Lantana camara)[2,4]. X. strumarium is a common monoecious annual herbaceous plant species belonging to Asteraceae family[5]. More than sixteen Xanthium species have been identified and the most common are X. strumarium and Xanthium spinosum. They are supposed to be originated from Central and North America and distributed worldwide[5,6]. There is wide variation, both within Xanthium populations in fruit size, pubescence, the number and length of spines and the degree to which the beaks and spines are hooked[7]. However, all Xanthium taxa are tetraploid (with 2n = 36). Xanthium spinosum is more homogeneous throughout its range than X. strumarium and there may be hybrid between them[5]. X. strumarium germinates at a wide range of temperature and can invade large areas of wetlands. It is the major troublesome weed of row crops such as soybeans, cotton, maize, corns and groundnuts in many parts of the world[8,9] causing the highest reduction in yield of all annual weeds[10]. It invades pastures and grazing lands causing reduction in forage production and poisoning domestic animals ARTICLE INFO ABSTRACT