|
1
| 2 | 3 | 4
| 5 | 6 | 7
| 8 | 9 | 10
| 11 | 12 |
13 | 14 | 15
| 16 | 17 |
18 | 19 | 20
| 21 | 22
Using Trichogramma
in Cotton IPM Programs |
18
Research into the use of Trichogramma wasps in cotton is
an ongoing topic of discussion world wide. Used in pest
control since the 1900’s, today, Trichogramma species
are one of the most widely used insect natural enemies in
the world. Secondary pest outbreaks, pesticide resistance,
more stringent pesticide regulation, and concern about human
health and environmental quality have renewed the interest
in Integrated Pest Management programs that emphasize biological
control. The commercially successful use of Trichogramma
to control the European corn borer in Europe has demonstrated
the potential of this approach.
Effectiveness
Trichogramma are among the smallest of insects, having
a wingspread of about 1/50th of an inch. Despite its size,
it is an efficient destroyer of the eggs of many moth and
butterflies, which are the leaf-eaters in the larval stage.
These insects disperse readily in their search for more
than 200 species of eggs to parasitize. The Trichogramma
seeks out eggs, but does not feed on or harm vegetation.
It is an effective tool because it kills its host before
the plant can be damaged.
Trichogramma activity enables reductions in
chemical applications and reduces resistance pressures on
those products. With a high reproductive rate, huge numbers
of wasps develop rapidly. The reliability and speed of this
process can be increased by the mass release of Trichogramma.
Use
Trichogramma are released to control some 28 different
caterpillar pests attacking corn, rice, sugarcane, cotton,
vegetables, sugar beets, fruit trees and pine and spruce
trees. Most releases are to control corn borers, sugarcane
borers and cotton bollworm. Although widely used, a recent
review of these programs worldwide concluded that “because
of considerable variability in success of releases and little
evidence of consistently successful application of Trichogramma,
the usefulness of these parasitioids is currently being
debated.
It is desirable to release the wasps into
crops adjacent to cotton such as corn, or on field margins
containing annual habitat. The wasp numbers will then increase
and migrate into the cotton in high numbers. If spraying
is then required in the cotton, wasp numbers are likely
to be higher and the adjacent crops continue to act as a
refuge and source of wasps.
Balance
According to Rincon-Vitova, a supplier of Trichogramma
in California, “beneficial insects are small pest-fighting
farm animals. Releases of Trichogramma can help tip the
balance of nature towards more biological pest control.
Creating sustainable biological control in cotton requires
a change in thinking, as the rules are very different from
chemical pest control. Even economic thresholds for pesticide
treatments change when cotton fields are teeming with biological
control organisms. When beneficials are on patrol in cotton
fields, higher pest levels can be tolerated for longer periods
of time without pesticide use, which translates into immediate
bottom line pest control cost savings. The objective of
adding new beneficials like Trichogramma to the cotton agroecosystem
is strengthening the natural enemy complex, and creating
an ecosystem where predator and prey (pest) are in better
balance.”
So, what does this mean to BASIC growers?
BASIC field staff have made releases of Tricogramma in two
of our enrolled fields where we have alfalfa interplanted
with the cotton. It is hoped that the addition of the wasps
will help to offset any increase in worm activity in these
fields. We will be monitoring closely to see if the Trichogramma
play a role in worm control.
Information for this article came from
The Trichogramma Manual by Allen Knutson, Professor and
Entomologist at Texas A&M University.
next article
|
