The response of eggs of the white potato cyst nematode Globodera pallida to diffusate from potato and mustard roots

Brief exposure of eggs of Globodera pallida to potato root diffusate not only initiated hatching but also caused the majority of unhatched juveniles to respond more rapidly to subsequent treatment with diffusate. Eggs previously exposed to diffusate had a peak hatch after 1 or 2 days compared with 4 days for untreated eggs. Mustard root diffusate prevented hatch, and further stimulation with potato root diffusate was necessary to re-initiate it. Eggs previously treated with potato root diffusate for 24 h were much more sensitive to drought than untreated eggs. These results are discussed in relation to the theory that potato root diffusate alters the permeability of the eggshell as an initial step in the hatching process.