Abstract
The reproductive isolation between two host races of Aspidiotus cryptomeriae was examined by comparing intra- and inter-racial responses of males to live virgin females and to sex pheromones in the laboratory. No inter-racial copulation of males to live females was observed for either sex combination. These results indicated that ethological isolation was present between the races. We showed by using a crude extracts test that both host races have female sex pheromones. Although an inter-racial response of males to female extracts was observed, it was much weaker than the intra-racial responses, suggesting that the sex pheromone system plays an important role in reproductive isolation between the two races. These results support the hypothesis that each host race is a distinct species.
