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 <> . 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.