|Control of Tadpole Shrimp-04
Project Leader and Principal UC Investigators
Brian Tsukimura,associate professor, Dept. of Biology, CSU Fresno
Fresno State scientists are working on an alternative to copper sulfate (bluestone) for treatment of tadpole shrimp. This invertebrate pest is of concern because it uproots young rice plants and reduces yield.
In contrast to a set of experiments conducted the previous year, a ground application of bluestone in test plots was ineffective in eliminating tadpole shrimp from rice fields. The application level was equivalent to 15 pounds per acre. These studies were also conducted at relatively warm water temperatures. A second aerial application was required for tadpole shrimp control.
The previous studies were conducted at relatively warm water temperatures. However, the water temperature in the 2004 CuSO4 (bluestone) treated plots at the time of inundation was low (15o C at midday), which is below the temperature at which tadpole shrimp are capable of hatching.
Ten days passed between inundation and the observation of tadpole shrimp in the plots. Tadpole shrimp are visible in the rice fields five days after hatching. This delay may have allowed the tadpole shrimp to hatch after the CuSO4 had dissipated and the CuSO4 concentration in the plots was low enough to allow survival. A second aerial application was required for tadpole shrimp control.
Methyl farnesoate (MF) is an organic compound derived from both crustaceans and plants that is under study as a possible tool for disrupting the shrimp’s reproductive cycle. This compound has been successfully incorporated into protein pellets that are attractive to the shrimp as a food source.
Work is continuing to refine the pellet “recipe” and the technique for manufacture in order to ensure longevity and effectiveness in limiting tadpole shrimp reproduction. Further work will concentrate on physiological studies to determine the potential for tadpole shrimp to develop resistance to MF treatment.
As farm equipment is the most likely way tadpole shrimp are spread, rinsing of equipment after use in an infected field is strongly recommended.
This research was funded jointly by the Rice Research Board and by a grant from the California Agricultural Technology Institute.