First Report of Dodder ( Cuscuta chinensis ) Parasitizing on Cnidium monnieri in Ningxia Hui Autonomous Region, China

Cnidium monnieri is an annual herb in the family Apiaceae, cultivated in China, South Korea, Mongolia, Russia, the USA, and Europe (Li et al. 2015). C. monnieri is a medicinal plant with a long history of use in traditional Chinese medicine, having been widely employed for centuries to dispel dampness and wind, kill parasites, and relieve itching. Beyond its medicinal value, C. monnieri emits volatile organic compounds (VOCs) that actively attract natural enemy insects, such as parasitoid wasps and predatory arthropods, thereby enhancing biological pest control in agroecosystems (Cai et al. 2021). In July 2025, a field survey was conducted in Xixia District, Yinchuan City, Ningxia Hui Autonomous Region, China (38.6500588°N, 106.14973898°E), where dodder extensively parasitized C. monnieri plants, with an incidence of approximately 20%–30%. The leaves of the parasitized plants were curled and had turned yellow, which led to plant death. Twenty-five dodders samples were collected from severely infected plants and transported to the laboratory for further analysis. The stems of dodders were thin and yellow. Inflorescences were glomerulate to dense paniculiform, often confluent. The calyx was 1.5 to 2 mm long and shallowly cup-shaped. The corolla was ovate to broadly ovate, with keel-like protrusions. Along the midrib, there were irregular multicellular protrusions with obtuse to round tips. The corolla was 2-3.3 mm long, the tube was 1-1.5 mm long, the lobes were 0.9-1.3 mm long, ovate, and the tip was obtuse to round. The stamens extend out of the corolla, the anthers were 0.4-0.6×0.4-0.5 mm, and the filaments were 0.4-0.8 mm. The fruit was capsule, 1.8-2.5×0.8-1.6 mm, nearly spherical to slightly flattened, not thickened, and semi-transparent. There were three to four seeds per capsule, measuring 0.85-1.2×0.8-1.1 mm. They were generally sub globose or ovoid in shape, and the seed coat cells were honeycombed or papillate. Based on the morphological characteristics, these dodders were identified as Cuscuta chinensis (Costea et al. 2015). To further confirm its identity, three dodder samples (D2, D5 and D6) were randomly selected and total genomic DNA was extracted. The internal transcribed spacer (ITS) region was then amplified and sequenced using the primers ITS1 and ITS4. The three obtained sequences were deposited in GenBank (accession no. PX582890; PX582891; PX582892). The BLAST results indicated that the sequences of D2, D5, and D6 were 99.34% identity with C. chinensis var. applanata (voucher Valdes 621, ENCB; GenBank accession JN234832) (Costea et al. 2011). To better understand the species level, a phylogenetic tree was constructed by the Bayes and maximum likelihood (ML) method using PhyloSuite software comparing sequences in this study with ITS of related species of the dodder species (García et al. 2014). In the phylogenetic tree, D2, D5, and D6 cluster with C. chinensis and its variant C. chinensis var. applanata, supported by a maximum likelihood bootstrap value of 64% and a Bayesian posterior probability of 0.17. Therefore, based on several morphological characteristics, sequence data and phylogenetic analysis, these dodders observed on C. monnieri in the Xixia District, Yinchuan City, Ningxia Hui Autonomous Region, were identified as C. chinensis. To our knowledge, this is the first report of C. chinensis parasitizing C. monnieri in China. The occurrence of C. chinensis may severely affect the yield and medicinal quality of C. monnieri, posing a potential risk to its production.