INTRODUCTION OF EXOTIC SPECIES

• One of the major impacts of human societies on nature has been the deliberate or inadvertant introduction of exotic species into ecosystems

• Often, these species prove to have greater Darwinian fitness in a given ecosystem than the species that evolved there originally, and so they outreproduce and displace these original species.

• Too, they often have no natural predators to keep their numbers in check, and so their populations explode to the point of becoming major problems to humans.

• I'll discuss several examples to illustrate these points:
  • Kudzu, a quintessential exotic invasive species, aggressively displacing native species

  • Feral pigeons, exotic but not invasive, not displacing native species but just being pests in the human environment

  • Africanized bees, genetic tinkering with an exotic (but not invasive) and economically important domesticated species, resulting in an invasive displacement of one subspecies by a hybrid cross that is dangerous to humans and unable to meet the economic function of the original domesticate

  • Yellow star-thistle, another exotic and highly invasive species, dangerous to a high-value domesticated species, the horse

Kudzu: A Deliberate Introduction that Went Terribly Wrong

• First, what is it? Kudzu is a weedy vine (Pueraria lobata) with often rampant invasive growth (a foot or more in a single day), which, if not controlled, soon covers anything in its path -- shrubs, trees, automobiles, or even small buildings.

  In Georgia, the legend says
  That you must close your windows
  At night to keep it out of the house.
  The glass is tinged with green, even so...

  From the poem, "Kudzu," by James Dickey who has also called it "the vegetable form of cancer"

• Common names for kudzu include:

  • mile-a-minute vine,

  • foot-a-night vine,

  • and the vine that ate the South.

• Kudzu was introduced to the United States in 1876 at the Centennial Exposition in Philadelphia, Pennsylvania. It became known in the South through the Japanese pavilion at the New Orleans Exposition (1884-1886).

  • Countries were invited to build exhibits to celebrate the 100th birthday of the U.S.

  • The Japanese government constructed a beautiful garden filled with plants from their country.

  • The large leaves and sweet-smelling blooms of kudzu captured the imagination of American gardeners who used the plant for ornamental purposes.

• Florida nursery operators, Charles and Lillie Pleas, discovered that animals would eat the plant and promoted its use for forage in the 1920s: Their Glen Arden Nursery in Chipley sold kudzu plants through the mail. A historical marker there proudly proclaims "Kudzu Developed Here."

• During the Great Depression of the 1930s, the Soil Conservation Service promoted kudzu for erosion control.

  • Hundreds of young folks were given work planting kudzu through the Civilian Conservation Corps.

  • Farmers were paid as much as eight dollars an acre as incentive to plant fields of the vines in the 1940s.

• Kudzu's most vocal advocate was one Channing Cope of Covington, Georgia who promoted use of the vine to control erosion.

  • Cope wrote about kudzu in articles for the Atlanta Journal- Constitution and talked about its virtues frequently on his daily WSB-AM radio program broadcast from his front porch.

  • During the 1940s, he traveled across the southeast starting Kudzu Clubs to honor what he called "the miracle vine."

  • Cope was very disappointed when the U.S. government stopped advocating the use of kudzu in 1953.

• The problem is that it just grows too well!

  • The climate of the Southeastern U.S. is perfect for kudzu.

  • The vines grow as much as a foot per day during summer months, climbing trees, power poles, and anything else they contact.

  • Under ideal conditions kudzu vines can grow sixty feet each year, and much of the South IS ideal!

  • It now covers about 7 million acres, including 2 million of forest

  • The USDA declared kudzu to be a weed in 1972!

• While they help prevent erosion, the vines can also destroy valuable forests by preventing trees from getting sunlight.

• This problem led Dr. James H. Miller of the U.S. Forest Service in Auburn, Alabama to research methods for killing kudzu.

  • In eighteen years of research, he has found that one herbicide actually makes kudzu grow better while many have little effect.

  • Miller recommends repeated herbicide treatments for at least four years, but some kudzu plants may take as long as ten years to kill, even with the most effective herbicides.

  • And then you've got to wonder about the effects of the herbicides on groundwater and other species.

• So, how about some pathetic attempts at environmentally sort of benign ways of slowing it down?

  • Dr. Errol G. Rhoden, along with other researchers at Tuskegee University, has successfully raised Angora goats in fields of kudzu which would otherwise be considered wasted land.

  • The goats keep the kudzu from spreading further while producing profitable milk and wool products.

  • Rhoden says constant grazing will eventually eradicate kudzu.

  • If kudzu is to provide a continuing food source, animals must be removed from the fields occasionally to allow the vines time to grow, so they do have an impact on kuzdu.

• Henry and Edith Edwards of Rutherfordton, North Carolina have found many uses for kudzu over the past 30 years.

  • Henry produces over 1,000 bales of kudzu hay each year on his Kudzu Cow Farm.

  • The hay is high in nutritive value.

  • Many people have found kudzu difficult to cut and bale.

• Current research may lead to new medicines made from kudzu, but for now only hamsters and mice can benefit from these drugs.

  • Research with laboratory animals at Harvard Medical School has revealed that a drug extracted from kudzu root may help in the treatment of alcoholism.

  • The drug is based on a 2,000 year old Chinese herbal medicine.

  • Several years of testing may be required before the drug can be made available for human consumption.

• In China and Japan, ground kudzu root (called kuzu) has been a common ingredient in foods and medications for centuries.

  • Kudzu is respected and enjoyed there.

  • It's far more versatile than say, turnips.

  • But kudzu grows better in the South than it does in its native lands.

  • Its natural insect enemies were not brought to the US with it, and I gather deliberate introductions of the bugs were less successful than the transplantation of the vine!

• If you'd like to see some photos of what this plant is capable of, together with some smart-aleck Southern commentary, try: http://www.ipass.net/~lineback/kud.htm (404)

The street pigeon, Columba livia

• I should preface this by noting that I actually LIKE pigeons !

• A wonderful discussion is an article by Norman Woldow, "Pigeon and Man (sic): A Spotty Old Friendship," in Natural History 81, 1 (back in 1972): 26-37!

• Indigenous to the mountains of the Middle East and parts of the Indian subcontinent

  • This kind of terrain provides nesting habitat for them: They do not make nests in trees, except for palm trees (again, widespread throughout the Middle East)

  • This nesting pickiness limited their distribution to those areas with suitable montane ledges and caves near enough to wild stands of grain

  • Then, people happened along and domesticated the grains -- a pigeon feast!

  • Even better, people started building tall buildings, e.g., temples

  • This may be why the bird wound up sacred, actually

• The pigeon, then, became an example of what Frederick Zeuner termed human contact with a scavenging (pigeon guests taking human food not wanted by people) or more commonly a robber (pigeons stealing food still wanted by people) species. Pigeons then became self- volunteering domesticates

• How people exploited them:

  • Dove towers

  • Pigeon tax

  • Carrier pigeons

  • Recreational genetics

    • Squabbing breeds

    • Racing/flying breeds

    • Fancy or toy breeds

  • So, pigeons accompanied people wherever they or their trade routes led

  • They are believed to have been brought to the New World in 1606

  • Some of them inevitably escape their coops or towers or get lost in races:

    • These are the source of all feral pigeon populations in the US

      • Wild

      • Feral

    • Natural selection favors only certain of the escapees:

      • Racing/flying breeds

      • Certain colors

        • Reversion to wild morph in cliff and beach environments

        • Blue check morph (1 gene mutation) in urban environments

        • Sometimes sooty or smoky mutations

        • Fewer than 10 percent are red, pied, speckled, or white

Africanized bees

• Humans are always tinkering with other species, trying to "improve" them, whether by conventional cross-breeding (as with the Green Revolution) or by transgenic experimentation now. Sometimes these experiments backfire badly.

• European honey bees, Apis millifera were imported to the New World, where they not only produce honey but pollinate a large portion of economically-important crops.

• They tend to have trouble producing honey in tropical South America, so, in 1956, the Brazilian Agricultural Ministry imported 63 queens from a highly aggressive African subspecies of honey bee, Apis mellifera scutellata, to create a bee better suited to their environment.

• Precautions were taken but Murphy's Law hit and a bunch of them escaped into the wild, and mated with European honey bee drones.

• The African bees' aggressiveness proved dominant in the resulting hybrids, as did a tendency to be very migratory (European honey bees are very loyal to a given location).

• The bees look almost identical to regular European honey bees, except they're a tiny bit smaller.

• Like all bees, a worker can only sting once, which eviscerates her and kills her.

• When a European honey bee nest is threatened, maybe 40 bees will come out and sacrifice themselves for it; when an Africanized hybrid bee nest is threatened, you might well get 4,000 coming at you.

• Their stings are no more lethal than a European bee's, but there are so many of them that you can get a fatal dose quickly.

• The colony can sustain this kind of mortality, because the Africanized queens can produce workers like crazy.

  • They can create more than 100 times as many workers as can a European queen.

  • Commonly, 40,000 to 60,000 individuals live in a nest.

• They are not very loyal to a given site.

  • European queens tend to stay with a nest and workers put a lot of effort into storing honey for the winter. New colonies are started around young queens.

  • Africanized bees swarm or divide to form new colonies about 6-8 times a year, and it is the old queens who take off with about half the workers; being tropical, they don't store food for winter as much.

  • So, they migrate as much as 200 miles a year.

• The US and Mexican governments eradicated all bees from a 10 miles strip of land across the narrowest part of Mexico back in 1966 to halt the migration. It didn't work.

  • By 1985, they first showed up in Mexico.

  • By 1987, they were in northern Mexico.

  • In 1990, they showed up in Texas and killed their first American victim in May, 1991.

  • They showed up in Arizona in 1993, killing someone there in Tucson, and 53 people were stung.

  • They show up in New Mexico also in 1993.

  • By October, 1994, they turn up in Chuckawalla State Prison in Blythe, California, and killed someone in Palo Verde in November, 1995.

  • Laughlin, NV, got their first killer bees in May, 1998.

  • By February of 1999, they had been reported in five Southern California counties: Imperial, San Diego, Riverside, San Bernardino, and Los Angeles.

• Well, folks, get used to them: They are here to stay.

• How to live with them:

  • Watch out when hiking, and keep your pets on leashes so they don't disturb a nest

  • Wear light not dark clothing and avoid using cologne, after-shave, and even insect repellent, which set them off.

  • If you find a suspicious nest near your home, contact the county government -- if you try to deal with them, you'll get killed.

  • Power equipment can set them off.

  • If attacked, run like crazy, covering your face and head, which they aim for -- we can outrun them as they are slow flyers. Get inside a car or building and shut the door -- the few who come in with you will abandon the chase and try to get out.

  • Do not dive into water -- they can see you and will wait for you to come up for air.

  • Scrape out the stingers with fingernails or knife blades or credit cards -- don't pull them out because you could squeeze more venom in. If you get more than 15 stings, get medical attention immediately -- 10 stings per pound of body weight is toxic for sure.

  • If you know you're allergic to bees in general, keep the antidote with you at all times.

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  Yellow Star Thistle (Centaurea solstitialis)

  • Indigenous to Southern Europe and the Middle East

  • Brought to California in the last century by European and Chinese settlers for honey-making purposes and for cattle forage (Bidwell is implicated locally).

  • It does make an excellent honey and it is a nitrogen-fixing plant and it is palatable in the early stages to cattle.

  • It is, however, cumulatively lethal to horses, producing a Parkinson's like disease in them, in which they cannot swallow food or even pick food up. There is no cure and the death is terrible, so the only thing you can do is put them down.

  • It also aggressively propagates, especially in disturbed habitat.

  • The plant is also a nuisance because of the spines.

  • It is now spreading throughout the West.

  • It is very resistant to pesticides.

    • Soaking it repeatedly in Roundup works

    • New pesticide, Transline (but it has soil activity)

  • Mowing and grazing works by displacing it with grasses

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  First placed on web: 04/04/99
  Last revised: 11/17/21

  Maintained by Dr. C.M. Rodrigue

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