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Invasive of the Month/Facts & Figures

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Invaded Series Species Profiles Table of Contents

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2007Invasive of the month: House Crow

The House Crow (Corvus splendens (Vieillot, 1816) is an aggressive and often invasive bird that originates from the Indian Sub-Content and parts of South-East Asia. It has been introduced to many tropical and sub-tropical countries (and there is even a small colony in The Netherlands) where it has become an urban and domestic pest, stealing human food, polluting human habitation, spreading human diseases, delighting in garbage and living in noisy colonies.

2008Invasive of the month: Prosopis

CABI and a number of collaborators have launched a project in Kenya that seeks to improve understanding of the country’s invasion by mesquite (Prosopis spp.) in order to enhance its management.

2008Invasive of the month: Water Cabbage (Limnocharis flava)

Water Cabbage (Limnocharis flava), a serious aquatic weed which displaces native species, restricts water flow and access, provides breeding grounds for disease vectors and disrupts rice production, has been officially recorded in Ghana for the first although unofficial records state that it may have been present for more than 10 years.

2008Invasive of the month: Japanese Knotweed

Japanese knotweed Fallopia japonica (Houtt.) Ronse Decraene [Polygonaceae], is arguably the most troublesome invasive alien plant in Europe and North America.  Since its introduction a popular new horticultural plant promoted for the Victorian garden, it has increased its range very rapidly and moved from prize-winner to pariah. 

2004Africa Invaded: Common Mynah

The common mynah Acridotheres tristris is another member of the starling family that is invasive in Africa. Sometimes called the Indian mynah because it is native to India and surrounding countries in south and south-east Asia, the bird has also become established in Australia, New Zealand, Hawaii, New Caledonia, Fiji, Western Samoa, the Solomon Islands, Cook Islands, and some other oceanic islands. In many cases it was introduced deliberately to control insect pests on crops, but sometimes accidentally when cagebirds escaped. The bird is an opportunistic feeder that eats almost anything, contributing to its success as an invader.

2006South America Invaded: Golden Mussel

The golden mussel is a freshwater bivalve native to China and south-east Asia. During the 1960s it became established in Hong Kong, and later in Japan and Taiwan. In 1991 it was detected in South America in the Rio de la Plata, the river mouth separating Argentina and Uruguay. The mussel probably arrived in the ballast water of ships visiting the ports of Buenos Aires and Montevideo. Aided by human movements and boat traffic, it rapidly spread upstream, advancing at an average rate of 240 km per year. Today it occurs throughout the Parana River system that links Argentina, Uruguay, Paraguay, Brazil and Bolivia.

2004Africa Invaded: Chromolaena

Chromolaena odorata – commonly called chromolaena, triffid weed or Siam weed – is one of the worst invasive plant species in the humid tropics and sub-tropics of the world. Its native range extends from Florida in the United States to northern Argentina, but it has invaded south-east Asia, parts of Oceania, and West, Central and southern Africa, where it is a major threat to biodiversity, agriculture and human welfare.

2004Africa Invaded: Acacia

The genus Acacia comprises some 1500 species, and close to 1000 of these are indigenous to Australia, where they are commonly known as wattles. Many other Acacia species naturally occur in Africa, spreading to other parts of the continent where they are considered serious invaders. Because of the vast number of acacia species, only a few are highlighted below, with a focus on some of the more serious Australian invasive species introduced to South Africa, highlighting a variety of negative consequences deriving from these introductions.

2004Africa Invaded: Parthenium

Parthenium hysterophorus, commonly called parthenium or congress weed, is an aggressive invader that is native to Mexico. The weed was first seen growing in Ethiopia in 1988 near food-aid distribution centres, so it is presumed that imported wheat grain was contaminated with its seeds. Once introduced, the weed was able to spread rapidly, as the seeds are readily dispersed in mud adhering to vehicles, machinery and animals, as well as by water and wind. The seeds can remain viable on the soil surface for up to two years, while buried seeds can stay dormant for as long as 20 years before germinating.

2004Africa Invaded: Prosopis

The genus Prosopis, commonly known as mesquite, includes more than 40 species, most of which are indigenous to an area ranging from Argentina to the southern United States. Several species have become invasive in Africa and other parts of the world, particularly the sub-tropical Prosopis glandulosa and P. velutina and the tropical P. juliflora and P. pallida. These species have been widely introduced as a source of fuelwood, fodder and shade, and are also used for sand stabilisation, soil improvement, or for hedges to contain livestock.

2004Africa Invaded: Leucaena

Leucaena leucocephala is another tree species that has been promoted by international agroforestry organisations as a fodder and firewood resource, but is widely reported as an invasive weed.