The emergence of larvae from free eggs of the potato-root eelworm heterodera rostochiensis (woll.)

A technique for conducting hatching experiments on eggs freed from cysts is described. The form of the hatching response was found to be similar to that of eggs contained within cysts, but the response of the free eggs to the hatching stimulus was slightly more rapid. Investigations into factors affecting free egg hatching showed that it was necessary to presoak cysts before extracting the eggs from them for hatching. Eggs taken from dry cysts or from cysts that had been opened or cracked before presoaking did not respond to diffusate. When free eggs and whole cysts were exposed to the same graded series of dilutions of diffusate, the L.A. values (i.e. log concentrations of hatching factor) derived from plotting the hatching curves were in very close agreement.