Simulation of Nematode Attraction To a Point in a Flat Field

Abstract

Computation of the movements of a hypothetical animal in a circular gradient show that all the varied approaches of male cyst nematodes to their females could be a result of one response mechanism in which the animal 'walks' or stops in response to the presence or absence of stimulus. A stimulus occurs when the receptor observes a concentration of stimulant above a threshold level and the receptor adapts so that, in effect, its threshold concentration approached the ambient concentration. The mechanism is in principle a kinesis because locomotion stops or continues; turning and head waving may be continuous or occur only after stopping; no directed bias to movement is incorporated although the tracks approach the source of the gradient as though klinotaxis occurred. Computation of the movements of a hypothetical animal in a circular gradient show that all the varied approaches of male cyst nematodes to their females could be a result of one response mechanism in which the animal 'walks' or stops in response to the presence or absence of stimulus. A stimulus occurs when the receptor observes a concentration of stimulant above a threshold level and the receptor adapts so that, in effect, its threshold concentration approached the ambient concentration. The mechanism is in principle a kinesis because locomotion stops or continues; turning and head waving may be continuous or occur only after stopping; no directed bias to movement is incorporated although the tracks approach the source of the gradient as though klinotaxis occurred.