In vivo pheromone activity in Nippostrongylus brasiliensis (nematoda).

Both sexes of Nippostrongylus brasiliensis were distributed in the anterior 50% of the mouse intestine from 4.5 to 8 days postinfection. Most worms were recovered from a region that represented 20% of the pyloric-caecal distance. The worms' dispersal increased to 70 to 75% of the intestine at 10 days postinfection. Food deprivation for 48 hr had a similar effect. Surgical transfer of females to the anterior region of the intestine induced dosage-dependent locomotion by posteriorly placed males. The males' response was reduced or eliminated by lengthy distances from females, peristalsis and pre-exposure to female pheromone. Females were attractive from 4 to 10 days postinfection, based on the male's in vivo response. Males were responsive to pheromone at 6 to 10 days postinfection.