The development of a Biocontrol program is a long-term process that requires multiple
interactions between many Federal and state agencies as well as cooperative ties
with overseas laboratories and foreign governments.
The process by which insects are located, evaluated, and finally released in the
United States is often thought of as a pipeline where different sections of the
pipe represent various facets of the process. Suitable insect candidates are 'put
into' the pipeline via overseas exploration and research for further testing and
evaluation until finally they are released, established, and the information for
their use is transferred to appropriate operational agencies.
Supporting the pipeline is an extensive base of knowledge that is derived from foundational
or basic research and includes such information as the insects' feeding preferences,
host specificity, suitable release environments, reproductive capacity, insect mortality,
insect impacts to target plant, etc. Such basic information is essential for successfully
releasing and transferring information on the use of the Biocontrol agents.
Below is a list of each major section of the pipeline. To view additional information
for a specific section, click on the underlined/green topic heading.
Overseas
The first step in the process of Biocontrol is that surveys are initiated in the
plant's country of origin or home range. That is, researchers carefully observe
the plant across its geographical range to determine what kinds of organisms are
feeding on or damaging the plant.
Developing a list of organisms that damage a specific plant species is accomplished
by visiting many different areas of the plant's native range and observing and collecting
large numbers of organisms that appear to feed on and damage the target plant.
Many factors are considered in the initial surveys. These include organism types,
damage, environmental conditions, the complex of agents, plant growth characteristics
under organism attack, etc.
Based on information gathered in the initial surveys, a tentative list of potential
insect Biocontrol candidates is compiled.
Once the initial list of potential insect herbivores is compiled via the initial
overseas surveys, the most promising organisms are collected to be used in small-scale
greenhouse/laboratory/field experiments.
The primary purpose of these initial experiments is to determine the potential of
a specific agent to feed on and damage only the targeted host plant. This is known
as the organism’s host specificity. Only organisms that will feed on and damage
the targeted pest plant are evaluated for use as Biocontrol agents.
In addition, these experiments are used to gauge the impact of the agent on the
target plant. Does the agent cause damage that could possibly reduce the invasiveness
or reproductive capacity of the target plant? Agents that are suitably host specific
but impact the plant only minimally are also eliminated.
Agents that pass these initial screenings undergo further overseas testing to confirm
initial observations.
Associated with this experimentation are additional field surveys designed to document
whether or not the selected candidate can be collected or feeds on other plant species.
Such field notes are important for subsequent host-specificity testing, for receiving
permission for releasing the insect into U.S. quarantine facilities, and later for
actual U.S. field releases.
During the entire overseas process, the target plant is surveyed continually for
other insect species that may have been missed during the initial surveys but which
may have the potential for being excellent Biocontrol agents.
The overseas portion of the Biocontrol pipeline is typically a long-term commitment
and may last indefinitely. The length of time required is dependent on the diversity
of the insect herbivores, the type of species collected, and the size of the plant's
home range.
Quarantine
Once the overseas portion is completed, host-specificity test results and associated
field notes are compiled and summarized. Such data analysis is the first step in
obtaining permission to bring the insects into a U.S. quarantine.
Permission to bring insects into U.S. quarantine facilities is granted by Animal
and Plant Health Inspection Service, Plant Protection and Quarantine (APHIS, PPQ),
based on recommendations by the Technical Advisory Group (TAG). The TAG is a group
of researchers and administrators from several Federal agencies including the USDA,
US Department of the Interior; EPA; the Weed Science Society of America; the National
Plant Board; and the Corps of Engineers. The major responsibility of the TAG is
to review petitions of three basic types;
- those concerning what plant or animal species scientists can work on for biological
control
- permission to introduce the agents into U.S. quarantine facilities for further testing
- the release of the insect agents from quarantine into U.S. field sites.
A lengthy document is drafted for the TAG by the overseas researchers in conjunction
with scientists conducting quarantine research. This document details the information
obtained in overseas field collections and experimentation.
Once permission is received from APHIS, PPQ, the Biocontrol agent is brought into
a U.S. quarantine facility.
As the name implies, the quarantine facility is constructed with special physical
and mechanical barriers that limit or exclude the escape of potentially dangerous
animals and plants. The facility is designed and managed so that no organisms can
enter or leave the building without being approved by laboratory personnel.
To date, much of the quarantine work on insect Biocontrol agents of aquatic plants
has been conducted at the Florida Department of Agriculture and Consumer Services
Division of Plant Industry's quarantine facility located in Gainesville, FL. The
work has been managed chiefly by personnel at USDA, ARS, and the University of Florida.
A new quarantine facility was completed in 2004 in Fort Lauderdale, FL and will
now accomplish much of the quarantine work for aquatic and riparian plant species.
The primary objective of the quarantine work is twofold
- to determine the insect's feeding and development preferences or host specificity
- to determine the potential effectiveness of the insect species as a Biocontrol agent.
The quarantine phase of the Biocontrol operation is one of the most important. It
is essential that only highly effective species that do not feed on, damage or lay
eggs on other economically important plant species agents are released. It would
do no good to release an organism that eventually causes problems by damaging other
important plant species after their primary target has been reduced to below problematic
levels.
Important questions that are asked during the quarantine phase include "What happens
to the insects when the target plant is reduced or eliminated by the insect Biocontrol
agents? and "Will the insects eat or damage other plant species?"
These and other questions are answered during the quarantine phase of the Biocontrol
process.
For example, to determine if the insect Biocontrol agents will impact other plant
species, the agents are placed in containers with a variety of closely related and
economically important plant species. Various impacts to these plants are measured,
including the amount of feeding, egg laying or oviposition, development, and damage.
Agents that show any sign of impacting nontarget plant species are quickly eliminated.
During this same time the effectiveness of the agents in reducing or impacting the
target plant is measured. Agents that may have looked promising during the overseas
portion of the Biocontrol research may be eliminated because of a lack of effectiveness.
The U.S. quarantine phase may last from 1 to 5 years. Length of time in quarantine
is dependent on a wide range of factors such as the insect species, previous research
on host specificity, and difficulty in rearing.
Release and Establishment
Similar to the quarantine phase, permission from APHIS, PPQ, must also be obtained
before the agents can be released from quarantine into U.S. field sites.
Again, a lengthy document is prepared by the researchers conducting the quarantine
research. This document is presented to the TAG and includes, among other items,
information on
- the taxonomy of the target plant
- the plants that were tested for host specificity
- the taxonomy of the Biocontrol agent
- host range tests
- the impact to nontarget plant species.
Once permission is received from APHIS, PPQ, the insects are ready for release into
selected field sites.
The first step before actually releasing the insect agents into U.S. field sites
is to develop large colonies of the agents.
Several procedures are used to develop large colonies of Biocontrol agents for field
release. Frequently the agents are subjected to mass rearing procedures using greenhouse/laboratory
facilities. The process for mass rearing the agents differs from species to species.
Ideally, rearing procedures are developed based on information on the biology of
the agent.
It is essential that agents released from mass rearing facilities be able to compete
favorably under field conditions. The artificial conditions created by the very
nature of mass rearing can, if the researchers are not careful, reduce the competitiveness
of the agents below acceptable levels to levels that will jeopardize the organism's
chances of becoming established.
At the time of this writing the only agents undergoing mass rearing are those that
feed on hydrilla. There are now two mass rearing programs for insect Biocontrol
agents of hydrilla, they are located at U.S. Army Engineer Research and Development
Center, Vicksburg, MS and at the Lewisville Aquatic Ecology Research Facility in
Lewisville, TX.
Another viable strategy for developing large numbers of the agents is to release
small numbers of the agents, which are collected directly from overseas locations,
into small aquatic systems or nursery areas. After population numbers in these nursery
areas are of a sufficient size, the agents can be collected directly from the field
sites and transferred to other selected field sites, or plants infested with agents
can be removed directly. Removal of infested plants is by far the least expensive
and probably the best manner to release high numbers of quality insects.
The primary goal of the initial release/establishment program is twofold:
- to develop appropriate release strategies for use by other agencies
- to document the effectiveness of the agents to impact and manage the target plant.
The initial releases are experimental in nature and are used to develop suitable
procedures for future releases. In most instances the release procedures are modified
many times in an attempt to fine-tune them to match the biology of the agent and
environmental conditions at specific sites. The numerous modifications made to the
release procedures are designed to increase the success for the establishment of
the agent across large areas in the United States.
Another objective of the initial release and establishment program is to develop
accurate and labor reducing methods to assess the impact of the agents on the target
plant. Evaluation techniques are important for gauging the impact caused by a specific
agent.
The length of time needed for successfully releasing and obtaining establishment
of the agents is very difficult to predict because the process may be continued
for many years. Releases that continue over many years are necessary because of
the large geographical ranges that must be covered. In addition, the agent's impact
must be accurately assessed. Unfortunately, this cannot be done adequately without
following the agents over several growing seasons.
Evaluation
It is extremely important to develop accurate and labor reducing methods to assess
the impact of the agents on the target plant. Evaluation techniques are important
for gauging the impact caused by a specific agent.
Evaluation techniques can vary widely and are strictly dependent on the organism,
type of damage, and plant species. Under ideal situations three types of experimentation/evaluation
techniques are needed. These include laboratory/greenhouse/tank based experimentation
where insect impact is measured under very controlled conditions. Such experiments
are often, in part, conducted under the quarantine phase.
The next type of evaluation method involves observing and measuring impact using
small field type situations such as ponds or coves. This often allows assessment
based under actual field conditions but with some measure of control since ponds
can more easily be observed continually. In addition, ponds can be manipulated to
some extent allowing for differences in plant growth, water level fluctuations,
and in seasonal effects.
The final type is concerned with actual in-field sites examining establishment,
population increases, and impact. This is the most critical evaluation since it
if from actual field sites that evidence accumulates indicating effectiveness across
large geographical areas.
Unfortunately, this is often the most neglected area of Biocontrol.
Technology Transfer
Transfer of information to operational personnel at the Federal, state, and local
levels concerning the "use" of a specific insect Biocontrol agent occurs after release
and establishment efforts have been completed.
Initial release and establishment efforts are considered completed after the Biocontrol
agents are established at many locations across a broad geographical range. In addition,
the agent's impact to the plant must be understood, which can be accomplished only
by monitoring the agent's effects through several growing seasons.
The information to be transferred varies and is dependent on the specific agent.
Generally, it includes how to determine the Biocontrol agent's population size and
subsequent impact to the target plant, visual clues of impact, possible interactions
with existing control technologies, and methods for augmenting or establishing the
agents in areas where the insect population levels may be low or nonexistent.
Technology transfer for biological control is unique in comparison to other more
traditional control technologies in that operational personnel normally do not actively
use the agents. That is, operational personnel do not apply the agents at specific
locations in an effort to achieve control at that location in a manner analogous
to what is done for chemical technologies. Instead, biological control agents are
often already present within a particular area and operational personnel assess
the agents' possible effects and ways to enhance these effects. More details on
"using" the agents will be included in later sections.
Foundational Research
This is one of the most important portions of the pipeline. Foundational or basic
research concerning life history, effectiveness, population growth, interaction
with existing control technologies, etc. is the base or foundation for the entire
pipeline. Without such basic research, Biocontrol technology would not be an active
and viable technology for aquatic plant control. Understanding the organism, plant,
and associated ecologies is essential for effective use of Biocontrol. It is what
supports the entire process.
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