Pheromone attraction in the soybean cyst nematodeHeterodera glycines race 3

MaleHeterodera glycines responded to female nematodes during in vitro bioassay. The male's response was dosage-dependent and significant with a pheromone source of more than five females. Male responsiveness was influenced by the pheromone diffusion and response times. Males were most responsive at three days after emergence from the host plant, while females were also most attractive at the same age. Light intensities that ranged from dark to bright had no effect on female location by the male, although bioassay in a nitrogen atmosphere eliminated sexual communication. Mate location was not significant below 25 °C and declined slightly at 30 or 33 °C. Bioassay at pHs from 5 to 8.5 showed a bimodal effect, with maximal attraction around pH 6.