Detection of heterodera mani in Western Australia

Abstract

The ryegrass cyst nematode, Heterodera mani, is reported from Western Australia for the first time. Cysts were recovered from soil samples collected on a broadacre cropping property near the town of Esperance. The production area is dominated by cereal/oilseed rotation and a species of annual ryegrass (Lolium rigidum) is a common weed issue in these paddocks. Morphometrics of cysts and second stage juveniles (J2s) from the Western Australian population were consistent with data from other reports of this species. Sequences of the mitochondrial cytochrome c oxidase I (COI) gene region were generated and matched those of H. mani from previous reports. Sequences of the large subunit ribosomal RNA (28S rRNA) were produced for H. mani for the first time. Although interspecific variation is relatively low for this gene in the Heterodera avenae species complex, our analyses indicate that 28S gene sequences sufficiently differentiate H. mani from other H. avenae-group members. Lolium rigidum is likely the host for the H. mani population discovered, although this requires further confirmation.