Effect of mercury vapour on the non-protein thiol content and respiration rate of eggs of the cattle tick Boophilus microplus (Acari: Ixodidae).

With continuous and ultimately lethal exposure of eggs of Boophilus microplus to mercury vapour, respiration and non-protein thiol decreased to low levels. With sub-lethal exposure, respiration decreased initially and then increased, whereas non-protein thiol (largely glutathione) increased initially and then decreased. This initial increase in glutathione (GSH) which probably resulted from an attempt by the organism to control or reverse the biochemical lesion, did not arise from the oxidized form (GSSG) through a shift in the equilibrium from right to left thus: 2GSH in equilibrium GSSG + 2H+ + 2e-. The significance of the results are discussed in relation to theories of GSH function and of Hg toxicity. The possible application of mercurials in tick control is discussed.