Integrative identification of Aphelenchoides fragariae (Nematoda: Aphelenchoididae) parasitizing Fuchsia hybrid in China

The strawberry crimp nematode (Aphelenchoides fragariae) is a serious pathogen of ornamental crops and an important quarantine object in approximately 50 countries and regions including China. One nematode population within the genus Aphelenchoides was discovered from diseased leaves of fuchsia plants (Fuchsia × hybrid Voss.) in Chengdu city, Sichuan province of China. Morphological and morphometric data were obtained using light microscopy and scanning electron microscopy. After detailed examination, the species was identified as A. fragariae. Three rDNA sequences of this species, including partial rRNA small subunit, D2-D3 expansion domains of the rRNA large subunit and internal transcribed spacer, were amplified and sequenced. Bayesian trees inferred from these three rDNA sequences were constructed, revealing that this species is placed in a high support monophyletic clade with A. fragariae but clearly separated from all other Aphelenchoides species. Moreover, host-suitability tests showed that the Aphelenchoides population not only can harm and reproduce in F. hybrid, but also in Fragaria ananassa and Pteris vittata (two common hosts of A. fragariae). In conclusion, the study confirmed A. fragariae identity of the nematode from F. hybrid in Chengdu city based on morphology, molecular analysis and host-suitability tests. To our knowledge, this is the first molecular and morphological confirmation of A. fragariae in China, and F. hybrid was first discovered to be attacked by A. fragariae.