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Biodiversity better than pesticide

Doctors Dr. W. Wyatt Hoback and Dr. Kerri M. Skinner of the University of Nebraska at Kearney and Dr. Robert K.D. Peterson and Dr. Sharlene E. Sing of Montana State University have combined their efforts to form RELEASE (Risk Evaluation Learning to Explore Alien Species Establishment) to help improve the understanding of the decision-making process that precedes the release of biological control agents.

Besides providing online lessons in identification, ecology, entomology and other sciences (at http://cgi.unk.edu/hoback/home.html), the Doctors provide information on successful alien species establishment.

On our farm, we rely on biodiversity to achieve a natural balance of predators and prey, and rarely suffer any crop damage because of our dedication to providing both habitat and food for the wild creatures who would not naturally want to eat our food!

 

The Successful Control of Saltcedar by Asian Leaf Beetles

 

In example, they point to the Asian Leaf Beetle to target Saltcedar (Tamarix spp.), a non-native, invasive tree that has been problematic in most southwestern states and some north-central states.

Saltcedar has infested about 1.5 million acres, increasing its range by a rate of about 50,000 acres per year.  It prefers riparian areas, especially waterways with receding surface water, and results in $127-$291 million in damages annually.

“The risk assessment for this non-native biocontrol agent release has been one of the most extensive and complete analyses to date. Research and testing of host-range parameters were conducted from 1992 to 1996 in Europe and Asia at cooperating facilities, along with select species tested in quarantine facilities at Temple, Texas,” encourage the Doctors.

Before making their recommendation, they test the alien species for host specificity and non-target effects (on phylogenetically related species, species in close proximity of infested areas, species with similar habitat requirements, and species of agricultural or horticultural concern).  Their tests utilize several experimental designs, including no-choice, choice and multiple choice for larva and adults. The survival of beetles and the extent of damage was measured.

In their tests, they found that the saltcedar was fed upon by both adult and larval stages, which enjoyed foliage, twigs and first-year shoots especially.  This caused the gradual dieback of stems, death of small plants and limited regrowth.

Expected results of beetle release are decreased saltcedar stand density, reduced saltcedar size (foliage cover), increased wildlife activity, decreased soil salinity, and restored groundwater.

And, proving their research, a northern Nevada release site has had considerable success with the biocontrol beetle release. In 2002, there were 5 acres noticeably affected by beetle defoliation, and in 2003 this increased to 500 acres. By 2004, the beetles damaged saltcedar trees in the surrounding 50,000 acres.

And, best of all, since the open field releases in 2001, there have not been any identified non-target effects of this biocontrol agent.

Similar success has been had with the decapitating fly controlling the fire ant, and the thistlehead weevil controlling the musk thistle.

 

How They Recommend Undertaking Risk Assessment

 

The scientists draw an example surrounding a salt shaker in a classroom.  11 Tablespoons would be fatal to a person weighing 150 pounds.  This threat is real, but risk assessment is required before taking action to prevent death.

First it is important to understand both the effects of exposure and the methods of exposure.

Analysis of how the salt could kill someone (exposure through ingestion, skin contact, inhalation, etc.) yields understandings of how to prevent that catastrophe, and might also illuminate the hazard of the shaker itself (which, if applied incorrectly to the body, could also be lethal). 

When these potential exposures are understood, probabilities of their occurrence can be calculated based on experimental or natural data. 

The Doctors fall short of requiring an examination of  requiring a financial analysis to determine whether it makes sense to prevent death by salt (or shaker), understanding that when lives are on the line, money is of little consequence.

In our opinion, this demonstrates uncommon ethical and moral fiber, and a loyal public service.  The cost of a person’s life (or the life of any other living  creature) cannot be quantified by money, even if their value as a resource to industry can be.

 

Interpretation

 

While it is impressive that these aliens have successfully controlled their target, it is more so that they have not complicated the ecology further by affecting other creatures.

A zero-tolerance for risk, while impracticable, is sometimes necessary when the lives of humans and other living plants, animals and microorganisms are involved.  Life is precious in all its forms, and it is better to do no harm  than to undertake something that will knowingly further destroy the delicate balance of an ecology.

While aliens are not uncommon, and species naturally migrate and disperse throughout the planet, the rapidity at which strange new creatures are being accidently and widely introduced has caused mayhem to the local environments that receive them. 

Change is best when it happens slowly, and the noble efforts of the RELEASE Group to help speed the stabilization of the biosphere are better than could be expected. 

By providing to industry another tool to rely upon in the control of pests besides chemicals, the RELEASE Group has performed a service to posterity.  The risks of further ecological collapse due to alien introduction are small when compared against the toxicity of many of the too-commonly used chemical control agents.

Besides, the cost of alien introduction is so small (and is, on top, a nearly one-time expense) that the savings to private and public purses is enormous.

 

In Motion Picture

 

An interesting video on the project is available online from the USDA at http://www.snarc.ars.usda.gov/is/video/vnr/saltcedar.htm

 

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