Variation in courtship signals and hybridization between geographically definable populations of the rice Brown planthopper, Nilaparvata lugens (Stål)

Populations of Nilaparvata lugens from 18 geographically defined and widely distributed regions in Asia and Australasia were maintained in the laboratory on growing rice plants. Crosses between some of these showed varying degrees of success in hybridization. Those between insects from Australia and the Solomon Islands had the lowest success rates, but in successful individual crosses there was little evidence of hybrid inviability. Behavioural barriers in the form of substrate transmitted courtship signals appeared to be primarily responsible for low success in hybridization. Pulse repetition frequencies of male calls were distinctive for different populations: those from Australia and the Solomon Islands showed the greatest difference. Divergence in mate recognition signals (pre-mating ethological isolating mechanisms) has apparently evolved in advance of general genetic incompatibilities (post-mating isolating mechanisms) in this species.