Effects of reproductive interference between Bursaphelenchus xylophilus and B. mucronatus on the development of pine wilt disease

Effects of reproductive interference betweenBursaphelenchus xylophilus and B. mucronatus on the development of pine wilt disease (マツノザイセンチュウとニセマツノザイセンチュウの繁殖干渉がマ ツ材線虫病の発病に及ぼす影響) Pine wilt disease is an infectious disease of pine trees.It is caused by the nematode Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle and is transmitted by cerambycid beetles of the genus Monochamus.The pathogenic nematode native to North America has been introduced to East Asia and westernmost Europe, where the non-pathogenic, closely-related nematode B. mucronatus is distributed widely.Once B. xylophilus invades susceptible pine forests, B. mucronatus is displaced rapidly by B. xylophilus.The species displacement has been implicitly considered to result from the interspecific competition for limited resources.Reproductive interference is caused by incomplete recognition of the other species and reduced fitness by mating attempts and copulation with the other species and so on.Interspecific competition through reproductive interference is characterized by asymmetric, frequency-dependent competition and brings several ecological and evolutionary consequences on species.Bursaphelenchus xylophilus and B. mucronatus are known to produce F 1 hybrids that cannot establish populations in most cases, suggesting the presence of reproductive interference between the two species.The aim of this study was to determine the effects of interspecific competition of nematode species on the development of pine wilt disease and the characteristics of their competition. Suppressive effects of B. mucronatus on pine wilt disease development and B. xylophilus populations in pine seedlingsTheories predict that one of the two competing species populations quickly displaces the other through reproductive interference in a frequency-dependent manner.Thus it is anticipated