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In Central California rice
fields, the tadpole shrimp, Triops longicaudatus, is an invasive pest
that can have devastating effects on rice yields. Copper sulfate, a
Class I Hazardous Material, is the standard means of tadpole shrimp
control, but it is becoming more expensive, and for organic farmers, has
been restricted by the USDA.
With increasingly harsher laws against chemical use, an organic means of
pest control is both desirable and a possible necessity. To help resolve
this issue, California State University, Fresno biology professor Dr.
Brian Tsukimura has spent several years developing a hormone-based
pellet that reduces reproductive capacity of tadpole shrimp. In his most
recent work, the hormone, methyl farnesoate (MF), was incorporated into
standard crustacean protein pellets that can be fed to tadpole shrimp.
Laboratory studies indicated that small doses (0.75 µg/g) are effective
in reducing tadpole shrimp fecundity, thus limiting future generations
of these crustacean pests.
In an attempt to increase the shelf life of the MF pellets, Tsukimura
incorporated MF into liposomes, thus reducing MF oxidation. Further
experiments confirmed the presence of the enzyme, Farnesoic Acid
O-methyl transferase, which is the final enzyme required in the
synthesis of MF.
The work was funded in part by the California State University
Agricultural Research Initiative (ARI), based at the California
Agricultural Technology Institute (CATI) at Fresno State.
Full project details, including technical information and data tables,
are available in the final report, accessible on the ARI website at
http://ari.calstate.edu. The
project is titled, “Control of Tadpole Shrimp by Methyl Farnesoate
Inhibition of Reproduction” (ARI Project #04-2-021).
Data also has been distributed through CATI-ARI flyers, presentations
and publications of the California Rice Research Board, presentations at
scientific societies, and refereed publications.
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