Effect of pH, mineral salts and fatty acids on the predatory Nematode, Parahadronchus shakili (Jairajpuri, 1969)

Abstract

Observations on the effects of pH, mineral salts and fatty acids showed that these chemicals are toxic to Parahadronchus shakili (Jairajpuri, 1969) Mulvey, 1978. The high susceptibility to the pH gradients ranging from 2.2 to 4.0 and 6.4 to 8.0 showed that these nematodes can not survive either in high acidic media or low alkaline media. The maximum life span at pH 5.8 to 6.0 shows that is the optimum pH range. The mineral salts of concentrations ranging from 0.4M to 0.05M showed different effects at different concentrations. The rate of survival was lower at higher concentrations. Copper sulphate was most toxic, while potassium carbonate was least. The fatty acids ranging from 1N to 0.01N also proved highly toxic, but the toxicity at lowest concentration of 0.001N was less. Formic acid proved highly toxic. The adults, in general, were more tolerant than the juveniles. The adult females were least susceptible while the first stage juveniles were most. The exposure to various chemicals also brought about changes in the posture and movement of the nematodes.