Mugwort is a perennial in the Compositae family distributed throughout Asia and Europe. The leaves are reported to have various pharmaceutical properties, e.g., antibacterial, antiviral, antitussive, and hemostatic properties, and have been used in traditional Chinese medicine for more than 2,000 years. In August 2011, a field of mugwort in Kunming, Yunnan Province, China, exhibited more than 90% incidence of whitish and rounded galls on the leaves. There were approximately 10 galls on each leaf, impacting the quality of the leaves for medicinal use. Parasitic nematodes were found upon dissection of the galls, then eggs, second-stage juveniles (J2), and mature males and females were observed. Through the morphologic observation of juveniles and female and male adults, the parasitic nematode was identified as Subanguina moxae (Yokoo and Choi, 1968) Brzeski, 1981 (3). Key morphological features are as follows: eggs (n = 20) measured 54.0 to 71.4 × 24.1 to 30.0 μm; J2 (n = 20) had the following characteristics: body length 689.3 to 873.2 μm (x = 775.5 μm); stylet length 8.2 to 9.8 μm (x = 8.8 μm); tail length 49.5 to 74.5 μm (x = 60.1 μm); a (total body length/maximum body width) ranged from 28.6 to 38.6 μm (x = 34.1 μm); and c (total body length/the length of the tail) ranged from 11.2 to 16.0 μm (x = 13.0 μm). Females (n = 20) had the following characteristics: body length 1,252.8 to 1,665.2 μm (x = 1,475.7 μm); stylet length 7.2 to 9.2 μm (x = 8.2 μm); V of 88.0 to 92.3 μm (x = 89.6 μm); a ranged from 17.6 to 24.5 μm (x = 21.3 μm); and c ranged from 20.2 to 28.9 μm (x = 22.8 μm). Males (n = 20) had the following characteristics: body length 994.2 to 1,453.6 μm (x = 1,253.2 μm); stylet length 7.5 to 9.9 μm (x= 9.1 μm); tail length 69.2 to 88.1 μm (x = 78.0 μm); spicule length 22.2 to 33.4 μm (x = 29.4 μm); gubernaculum length 10.4 to 14.2 μm (x = 12.2 μm); a ranged from 23.1 to 37.2 μm (x = 29.9 μm); and c ranged from 13.9 to 18.7 μm (x = 16.1 μm). Amplification of the rDNA-internal transcribed spacer (ITS) region and the D2/D3 (1) fragments of the 28S RNA with universal primers rDNA1/rDNA2 and D2A/D3B yielded PCR fragments of 934 bp and 754 bp, respectively. The ITS sequence (JN865234) and D2D3 sequence (JN885540) were submitted to GenBank. The ITS sequence (JN865234) exhibited 99.4% similarity with Mesoanguina moxae (AF396314) (synonym of S. moxae) (4). S. moxae has been identified from the common mugwort in Japan (2) and in China, was reported to infect wheat in Guizhou Province, but to our knowledge, this is the first report of this nematode affecting mugwort in Yunnan, China.
References: (1) S. Amiri et al. Eur. J. Plant Pathol. 108:497, 2002. (2) K. Daigo et al. Bull. School Agric. Meiji University. 56:237, 2007. (3) M. R. Siddiqi. Tylenchida: Parasites of Plants and Insects. CABI Publishing, New York, 2000. (4) S. A. Subbotin et al. Mol. Phylogenet. Evol. 30:226, 2004.