Extremely Sensitive Thermotaxis of the Nematode Meloidogyne incognita.

Eggs of the root-knot nematode Meloidogyne incognita were acclimated to 23 C. Newly hatched second-stage juveniles migrated toward higher temperatures when placed in shallow thermal gradients averaging 23 C. The threshold gradient for this response was below 0.001 C/cm, with a best estimate of 4 x 10 C/cm. Calculations of physical limitations on thermotaxis indicate that this sensitivity is well within the limits of what is physically possible.