Biological control is most effective when used together with other
compatible pest control practices in an integrated pest management
program. Many control programs use a combination of techniques to
deliver rapid control yet provide a longer-lasting cost effective
control program. Mechanical control or herbicide control programs
for aquatic weed can be combined with biological control to provide
such a program. When combining techniques it is a good practice to
maintain an otherwise uncontrolled area of plants for the insects
to use as a nursery to establish and build up.
What are the alternatives to biological control of weeds?
There are three main methods used for control of weeds: biological,
mechanical, and chemical. Mechanical control includes mowing, hoeing,
cultivation, and hand pulling. Chemical control is the use of herbicides.
You can also use a combination of these three methods in an integrated
weed management approach which some authorities would consider as
the fourth method.
What are the advantages of biological control?
The advantages of biological control are
- It is inexpensive
- It poses little threat to non-target organisms
- Once established, biological control agents are self perpetuating
and can spread on their own
- Little additional effort is required once a biological control
organism is established, while other control methods require action
or inputs periodically
- The environmental impact is generally low
What are the drawbacks to biological control?
The main drawbacks to biological control of weeds are:
- There is always some risk and concern with introducing an exotic
organism into the environment. The main concern is a host shift
of a biological control agent that results in the agent feeding
on a desirable plant.
- Biological control agents are not available for all target pests.
Some of the target weeds are closely related to plants that are
desirable so the risk of introducing an agent is too great.
- Research time and money is needed to locate biological agents
and screen them for host range before the agents are released. It
generally takes years of research and testing before agents are
released.
- Biological control takes place slowly in most cases. Localized
weed problems may not be eliminated quickly enough to satisfy public
opinion.
- Biological control relies on populations of the weed and the
agent to maintain the system. Thus, weeds are not completely
eliminated. Also, there is often highs and lows in population levels
of the weed and the agent both in time and space. Thus, there are
some situations where biological control does not seem to work well.
If there are advantages and disadvantages how is the decision
to use biological control
determined?
The decision is made on a case-by-case basis. The potential impact
of the weed, the alternative control measures available, the risk
to the environment, and the consequences of doing nothing are all
considered. The scientific information and the social values all influence
the decision. Once the organism is released, there may be little
good alternative to reverse the decision, so this decision is taken
seriously. This is further complicated by the fact that social values
change through time and that the scientific information available will also
change as new information becomes available. There a number of regulations
in place that impact the release of organisms.
John Jackman, June 26, 1999
What is the Difference between "Laws" and "Regulations"
Governing the Biological Control?
Law is the term used to denote what has been passed by the legislature
and appears in the Texas Agricultural Code . Regulation, on the
other hand, is the law as interpreted by the administration, such as
the state department. Laws can be vague in language, but regulations
are more to the point and specific.
Oct. 20, 1999. Awinash Bhatkar, Ph. D., Texas Department of Agriculture
