Sexual attraction and pheromonal dosage response of Nippostrongylus brasiliensis.

Seven-day-old male and female Nippostrongylus brasiliensis exhibit mutual heterosexual attraction in vitro. A strong dosage-dependency to female pheromone was present in responding male N. brasiliensis. Male helminths were significantly attracted to as few as three female worms. Female helminths were less responsive to male pheromone dosage in vitro. No indication of male homosexual attraction, arrestment, or repulsion was evident. Female homosexual trials suggested that an inhibition of movement occurred in the responding female helminths.