The 96 hrs LC50 values for malathion and glyphosate was determined to be 9.1 ppm and 5.5 ppb, respectively on the fairy shrimp, Streptocephalus dichotomus preadults. The 1/5 of 96 hrs LC50 of malathion (2.0 ppm) and glyphosate (1.1 ppb) respectively was chosen. The sub lethal toxic effect of each of these pesticides on the acetylcholinesterase activity (AchE) of S. dichotomus was assayed on day...