Environmental stress and parasitic infections: II. Effects of gramoxone and hexadrin (pesticides) on the survival characteristics of Fasciola gigantica miracidia.

Miracidia of Fasciola gigantica have a maximum longevity of 9 h. Miracidial survival was found to be age dependent and the instantaneous mortality rate increased exponentially with miracidial age and pesticide treatment. Mortality of the pesticide-treated miracidia differs significantly from that of the control. The LC50 value for Hexadrin was calculated at 1.93 ppm and for Gramoxone at 0.75 ppm. Dosage-mortality lines when tested statistically show no significant difference between the two pesticides at 95% level of confidence. The toxic effect of the pesticides was enhanced by synergism between the pesticides.