Invasion of Salvina Molesta kariba weed
The plant Salvinia molesta , generally known as Giant Salvinia or Kariba weed, is a free floating pterophyta indigenous to south-east brazil (Julien et. al 1987). Today plants and animals are shipped, sometimes accidentally, all over the globe to zoos, botanical gardens, and for commercial and agricultural purposes. A small minority of "alien" plants, or introduced, species become ecological as well as economic disasters. Although they may have been innocuous in their native region, these species are transformed into aggressive pests or weeds that invade and dominate their new environment (Barrett 1989) Nowhere are these biological invasions more evident than in the rivers lakes and reservoirs of the world. Giant Salvinia, one of the worst aquatic weeds in the world, exemplifies this problem. It is notorious for it's ability to colonize large areas of water in a short space of time. The explosive growth of these plants has caused difficulties in North America, Africa, Asia, and Australia Salvinia is a sterile floating fern native to South America (Julien et. al 1987). The basic morphological module of Salvinia is a ramet, each of which consist of a segment of rhizome bearing three di
Economic constraints were also the main reason for failure of physical or mechanical controls. Once the weed is established, biomasses of about 80 tonnes per hectare fresh weight and the potential for rapid regrowth make this impractical. The use of weed harvesting machines was considered in Australia, but was abandoned because the growth of the plants exceeded the removal capacity of the weeds (Thomas and Room 1996). Seagrave, C. Aquatic Weed Control. 1988. Fishing News Book, Inc. Great Britain. The major breakthrough in Control of Salvinia came on Lake Moondara in Australia, where biological control proved to be successful against Salvinia. A new beetle species, Cyrtobagous salvinidae, was discovered in Salvinia's native brazil that fed exclusively on Salvinia. The beetle was brought to Australia and released where it rapidly destroyed and infestation of kariba weed covering two square kilometers. The beetle's most spectacular success occurred in Papua, New Guinea where the beetle consumed two million metric tons of the weed in just two years (Barrett 1989). Other beetle programs are currently under way all over the world. The success of the beetle is due to the fact that it feeds selectively on growing points, which must be of considerable significance to a plant which relies on vegetative propagation. The larvae tunnel through the rhizome destroying vascular tissue (Thomas and Room 1986). Since Salvinia is asexual, the world's entire population of the plant is oostensibly genetically identical. The lack of variation, suggests that the susceptibility of the weed to C.salvinae should not differ from place to place. However, biological control is not perfect and there are a few problems to consider with biological control. C.salviniae eggs will not hatch below 19 degrees Celsius. Since salvinia will continue to grow at 10 degrees Celsius and can survive light frosts it is clear that the plant will survive in areas which, for part of the year at least, will not support C. salviniae (Thomas and Room 1996).
Some common words found in the essay are:
Mitchell Thomas, Salvinia Malaysia, Salvinia Barrett, Papua Guinea, America Julien, Infestations Texas, Guinea Malaysia, Australia AF101, Salvinia Kariba, River Guinea, salvinia molesta, biological control, giant salvinia, thomas 1986, control salvinia, et al, kariba weed, jacono 2000, mitchell thomas 1972, thomas 1972, north america, et al 1987, salvinia molesta journal, julien et al, caffrey et al,
Approximate Word count = 2265
Approximate Pages = 9 (250 words per page double spaced)
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