Meeting Abstract

92.3  Friday, Jan. 7  Bioassay to determine toxic effects of imazapyr on Daphnia BAUTISTA, J.A.*; WILSON, B.A.; Texas A&M International, Laredo jesusbaut@live.com

The purpose of this experiment was to determine the toxic effects, if any, of imazapyr afflicting daphnia ( Daphnia manga). Arundo donax, aka Carrizo cane, flourishes on the South Texas border region and not only does it trigger problems for government agents but to surrounding vegetation as well. The application of Imazapyr along the Rio Grande River would negate the nuisance the cane has fostered. Daphnia for this experiment were exposed for 120 hours at a range of concentrations (0, 0.35, 3.5, 35 and 70 µg/l) and monitored every 24 hours to determine the mortality rate. The concentrations tested during this study are the expected concentrations as determined by the US Environmental Protection Agency at the expected Imazapyr application rate. Upon carrying-out the experiment, it was determined that the LC₅₀ for Imazapyr on daphnia is between 0.35 µg/l and 3.5 µg/l. There were a significant number of deaths in the daphnia exposed to 3.5 µg/l (p = 0.018), 35 µg/l (p = 0.02) and 70 µg/l (p = 0.009) of Imazapyr in contrast to the control.