Exploration For Biological Control Agents
Biological control of weeds is
mainly done by
herbivores or pathogens from the weeds natural environments. It
this native range that a large number of natural enemies, herbivores
pathogens, are found, and have had millions of years to adapt to the
plant. Thus the first step in a biological control program is the
for natural enemies to control the target weed that has been
These foreign explorers filter among the enemies and look for species
control the weeds.
A lengthy process must be followed and approved by the International
Best Practices for Classical Biological Control of Weeds, which
plant being labeled a noxious weed and being targeted for biological
foreign exploration starts and may continue for years. The goals
experimental period are to thoroughly observe the native environment of
plant targeted and then collect and define the host range of herbivores
pathogens. Sometimes release agents are approved within 18
usually the process is much more extensive.
State and federal agencies as well as miscellaneous stake holders help
this expensive foreign exploration. An estimated $250,000 for
weed per year is the minimum amount needed for this type of biological
Research laboratories are located overseas and nationwide in order to
their native habitats.
Process of Exploration
The first step in the exploration process involves an extended survey
available material on the plant species and a climate comparison
plant here and in its native range. Next, the exploration begins
area where the target plant is native (many of our Montana weeds come
from Eurasia). Such things as moisture,
temperature range, altitude, etc., are then studied. Surveys are
done to look at many things including; the season,
and even do night surveys to try and cover all aspects of the studied
species. Right at the site the natural enemies are searched
plants, or samples of collected plants.
When they think they have found a possible biological control agent,
are collected right from the plants. This may be done using
hands, or an
aspirator (bug sucker). Next, these specimens are sent to
they are identified and molecular geneticists characterize them.
agents are labeled as a new species a representative specimen is
the holotype. During each collection field data, site
field data sheets are filled out. These include: name,
latitude/longitude, topography, vegetation, collection date, time, and
These agents are then sent to laboratory colonies (still on the
continent of origin). Here they can
studied and observed. At these laboratories, many detailed
studies are done such as: host range, impact assessments, and
Usually in a 2 to 3 year span, the agents are monitored. During
the information is used to know the growth stages of the weed and the
allows us to know when the next biological control release should be,
successful the agent has been.
To sum up foreign exploration, it can be done in 7 steps. First,
are observations for the host range. Next, the agents are taken
where they are looked at as biological control agents. Then,
many studies done which include: biological studies, starvation
studies and weed impact
studies. Finally, the agent is released and observed on how well
working. As soon as these steps are done, the USDA Animal and
Health Inspection Service Plant Protection and Quarantine can approve
agent. Right after this is done arrangements to ship the agent
to North America and do more studies and trial releases, are made.
Clark, Janet K. Biological Control of
Invasive Plants in the United States. N.p.: Oregon State
University Press, 2004.
By M. Battaiola, WHS student,
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