When a species is transported far from where it evolved, usually one of 2 things happen: it either dies off or else it spreads like wildfire. If the climate, rainfall & food supply are enough & the right kind - it spreads, without the usual limit of diseases or predators (or predatory insects) that have evolved along with the species in its home turf.
The list of invasive species in the US is long & troublesome: gypsy moth, asian bark beatle, bullfrog, water lily, lamprey, zebra mussel, africanized honeybee, fire ant - just to get you started, there are more.
;-)
2006-09-17 07:36:43
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answer #3
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answered by WikiJo 6
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Natural Enemies Of Kudzu:
A systematic survey for kudzu biocontrol agents was initiated in May 1999. At each of the four survey sites, five vines were chosen for sampling. Insect feeding, mating, and egg laying behavior was observed at 10-day intervals from May through November. Representative insects, and herbarium specimens of their feeding damage were collected and preserved. Defoliation was visually estimated in five 1 ft2 areas on each vine. The main vine and branches were monitored for feeding damage and gall formation.
The insects that fed on kudzu are still being identified. So far, seven out of 25 species (Deporaus sp., Alcidodes trifidus [Pasco], Sagra femorata [Drury], Aristobia hispida [Saunders], Paraleprodera diophthalma [Pascoe], Anomala corpulenta [Motschulsky], and Epicauta chinensis [Castelnau]) are known to feed on other crops (often beans), and therefore, have been dropped from consideration. Leaf-feeding beetles and sawflies that have no other known hosts have been identified. Two kinds of weevils were found to attack the succulent stems, and eight kinds of large beetles (Cerambycidae, Buprestidae, Scarabidae) lay eggs and develop as larvae in the main vines or roots.
Six fungal pathogens have been identified by collaborators at South China Agricultural University (Jiang et al.., 2000). One Phycomycete (Synchytrium puerariae P. Henning) Miyabe (Chytridiaceae) may hold some potential as a biological control agent. This pathogen has been reported on several Pueraria species from Japan, New Guinea, Java, the Phillipines, India, China, and California (specimen at National Fungus Collection, Beltsville, Marlyand (Karling, 1964), but further investigations are necessary to confirm its host specificity.
Host Range Tests and Results
Preliminary host range testing with soybean and peanut were begun in the summer of 2000. As far as possible, initial host testing will be conducted in China, where quarantine facilities are not required for these native insects. In the later screening stages, extensive testing of American plants and crops will be conducted in U.S. quarantine facilities to ensure host specificity before any insect can be released.
Biological Control Using Pathogens Native to the United States
Pseudomonas syringae pv. phaseolicola. This bacterium is the causal agent of “halo blight” of bean and kudzu, causing a small necrotic leafspot surrounded by a bright halo of chlorotic tissue. Zidak and Backman (1996) reported that the bacterium could kill eight- to ten-week-old kudzu seedlings, but produced few, if any, secondary infections under fairly dry conditions in the field.
Myrothecium verrucaria (Albertini and Schwein.) Ditmar: Fr. (Moniliales). This fungus has a fairly broad host range. Yang and Jong (1995) reported good control of leafy spurge, and eight other Euphorbia species using isolates of this fungus. Walker and Tilley found that an isolate from sicklepod (Senna obtusifolia [L.] Irwin and Barneby) affected a number of important crops, ornamentals, and weeds, representing six different families. Sprays directed to soybean stems and lower leaves did not reduce soybean dry weight (Walker and Tilley, 1997). It was patented for sicklepod biocontrol, and, although originally isolated from sicklepod, it is even more effective against kudzu. Two years of testing in Mississippi demonstrated that the fungus attacks leaves and stems, with greater activity at 25 to 40°C than at 10 to 20°C. Field tests demonstrated that 95 to 100% control could be achieved within 14 days of inoculation by girdling runner stems with this fungus, which produces asexual spores in a sporodochium, with a matrix suggesting dispersal by splashing rain. In inoculation studies, a surfactant was needed for good infection (Boyette, 2000). A patent for kudzu control has been applied for.
Colletotrichum gloeosporiodes (Penz.) Penz. and Sacc. in Penz. (Sphaeriales). A strain of this widely-distributed pathogen was isolated from kudzu in Houston County, Georgia, and its virulence was increased by repeated selection for growth on Czapek Dox medium amended with kudzu extract. Field inoculations showed a synergistic effect was achieved by inoculations of spores together with 20% of the recommended rate of dicamba. The fungus attacks both leaves and vines, and produces asexual spores in a pycnidium (Farris and Reilly, 2000).
Reasons for Success:
Kudzu has proved to be a major problem for the United States. Since the vine grows so rapidly, it is able to quickly encroach on and choke out natural vegetation. When kudzu grows into a forest, it blankets the floor with its vines and runners and prevents the growth of any new trees (Blaustein, 2001). It also destroys the older trees by covering them and blocking out the light they need to survive. Since kudzu is also very heavy, it is able to pull down structures that it is climbing on. This destruction of natural vegetation is profoundly disturbing, mostly because of kudzu's ability to choke out all of its competitors. This means that in a few years, kudzu will be one of the only, if not the only plant species in the area, dramatically reducing the biodiversity. This also means that indigenous animals may lose a great proportion of their natural food source.
Kudzu also poses a threat to cultivated plants. It takes over farm fields and destroys many valuable crop plants. Ironically enough, the plant that was once dubbed the "agricultural wonder" is now the agricultural curse. It was once actively planted to try and save the very farmlands that it is now so busy destroying.
Wildlife and agriculture are not the only things that suffer from the kudzu invasion, many aspects of industry have also been negatively affected. Kudzu encroachs upon train tracks and when the train runs over it, it collects slippery slime from the crushed plants. The result of this is slipping and sometimes even derailment, making it very unsafe for any train to run on tracks that are not cleared regularly. In order to do this, companies that own railroads have to allocate a certain amount of money per year to deal with the kudzu problem (Blaustein, 2001).
The Kudzu vine has also exhibited a disturbing tendency to climb. Not only does it cover trees, but it also goes for utility poles. Once the vine has gone all the way to the top of the pole, it begins to spread out across the lines, slowly weighing them down. Eventually, the lines snap and must be repaired. Kudzu has been known to climb up poles as high as eighty feet and it even destroys high tension wires and high voltage transformers (Watson, 1989). This means that utility companies, like railroad companies, must devote considerable amounts of money and manpower to periodically cleaning away kudzu. If the companies fall behind, the kudzu can quickly snap lines and interrupt power of phone service to many people. All said, power companies in the South devote around $1.5 million a year to controlling kudzu infestations (Blaustein, 2001).
Other types of man made structures are also at risk. Kudzu often covers and pulls down abandoned houses, or sometimes even inhabited houses. This is a huge cause for concern to the people who live in these houses. One elderly woman wrote a letter to Dr. James Miller who works for the U.S. Department of Agriculture and is an expert on kudzu. She recounted how her property was being taken over by the vine and how she and her husband had worked for many years to hold it back, but that he had recently died. She felt that she was unable to fend off the voracious kudzu and confessed to having constant nightmares that involved being attacked and covered by kudzu (Blaustein, 2001). Obviously, kudzu and the property damage that it causes are great sources of stress for many people.
In the short time that it has been on this continent, kudzu has had an enormous impact on culture, especially Southern culture. Southerners have a love/hate relationship with the vine. In recent years, it has become more and more obvious that kudzu is here to stay and in spite of the problems that it causes, people have responded with a mixture of reconciliation and enthusiasm. Kudzu can prove to be a very useful plant, not only is it edible to both humans and livestock, but its vines can be twisted into wreaths or baskets, and the leaves can be used for shade. Southerners relationship with kudzu is perhaps best evidenced by the multitude of names into which the plant is incorporated. Most of these are the names of bands or musical groups such as "The Kudzu Kings", "The Kudzu Krooners", or "The Kudzu Quartet" (Blaustein, 2001). There are also several publications that use the name kudzu such as The Kudzu Gazette, not to mention Kudzu the comic strip.
Many uses have been found for the plant. Soup can be made from its leaves and the starch in its roots can be extracted and used in cooking. The Japanese have used it for centuries for this purpose. It may also have some useful medicinal powers, it has been used in China as a treatment for a variety of ills. The fibers can also be made into paper, or woven into cloth (Mitich, 2000). Diane Hoots and Anita Baldwin co-authors of the book Kudzu: The Vine to Love or Hate have come up with many novel uses for the plant.
2006-09-17 08:16:10
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answer #7
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answered by phd4jc 3
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