Bursaphelenchus

Bursaphelenchus
Bursaphelenchus xylophilus
Scientific classification
Kingdom:	Animalia
Phylum:	Nematoda
Class:	Secernentea
Subclass:	Tylenchia
Order:	Aphelenchida
Superfamily:	Aphelenchoidoidea
Family:	Parasitaphelenchidae
Subfamily:	Bursaphelenchinae
Genus:	Bursaphelenchus Fuchs, 1937
Species
About 70-90, see text

Bursaphelenchus is a genus of nematodes (roundworms) in the order Aphelenchida. Most are obligate mycophages, but some feed on wood, with two species, the red ring nematode (B. cocophilus) and the pine wood nematode (B. xylophilus), economically significant as pests of coconut palms and of pine trees, respectively. Given that Bursaphelenchus species are usually hard to distinguish from one another except by trained helminthologists with access to microscopes or DNA sequence analysis, the entire genus is put under quarantine in some countries. Where this is not the case however, these nematodes are becoming established as model organisms for nematode developmental biology, ecology and genetics.^[1]

As of 2009, there are about 70^[2] to 90^[3] species in the genus. New taxa are described frequently.

Ecology

Bursaphelenchus contains a single described hermaphroditic species, okinawaensis, and over 100 described gonochoristic species.^[4] They inhabit soil or decaying wood, feeding on the wood itself or fungal hyphae growing in it, such as those of grey mould (Botrytis cinerea). They are sometimes beneficial when they reduce the fungal load inside the wood, but when they consume the plant tissue they are known to cause the death of living trees.^[1]

These nematodes are phoretic, dispersed between trees when their dauer larvae are transported by insects. Species involved include bark beetles, weevils, flat-faced longhorn beetles such as sawyer beetles, and soil-nesting bees. The process of dauer larva formation is not well understood, but it is of research interest because it is significant in the epidemics of plant diseases caused by these nematodes, such as pine wilt.^[1]

Selected species

Bursaphelenchus includes:^[1][5]

Bursaphelenchus abietinus Braasch & Schmutzenhofer, 2000 Bursaphelenchus abruptus Bursaphelenchus africanus Braasch, et al, 2007 Bursaphelenchus anatolius Bursaphelenchus antoniae Bursaphelenchus arthuri Bursaphelenchus borealis Bursaphelenchus chitwoodi Bursaphelenchus clavicauda Bursaphelenchus cocophilus – red ring nematode Bursaphelenchus conicaudatus Bursaphelenchus doui Bursaphelenchus eggersi Bursaphelenchus eremus Bursaphelenchus fraudulentus Bursaphelenchus fungivorus Franklin & Hooper, 1962 Bursaphelenchus gerberae Bursaphelenchus hellenicus Skarmoutsos, Braasch & Michalopoulou, 1998 Bursaphelenchus hildegardae Bursaphelenchus hofmanni Braasch, 1998 Bursaphelenchus hunti

Bursaphelenchus hylobianum Bursaphelenchus kevini Bursaphelenchus mucronatus Bursaphelenchus okinawaensis Kanzaki, et al., 2008 Bursaphelenchus paracorneolus Bursaphelenchus parvispicularis Bursaphelenchus pinasteri Bursaphelenchus piniperdae Fuchs, 1937 Bursaphelenchus platzeri Bursaphelenchus poligraphi Bursaphelenchus rainulfi Bursaphelenchus sachsi Bursaphelenchus seani Giblin & Kaya, 1983 Bursaphelenchus sexdentati Rühm, 1960 Bursaphelenchus sinensis Bursaphelenchus singaporensis Bursaphelenchus thailandae Bursaphelenchus tusciae Bursaphelenchus vallesianus Bursaphelenchus xylophilus – pine wood nematode, pine wilt nematode Bursaphelenchus yongensis

References

1. Kanzaki, N.; et al. (2008). "First report of parthenogenesis in the genus Bursaphelenchus Fuchs, 1937: A description of Bursaphelenchus okinawaensis sp. nov. isolated from Monochamus maruokai (Coleoptera: Cerambycidae)". Zool. Sci. 25 (8): 861–73. doi:10.2108/zsj.25.861. PMID 18795821.
2. Kikuchi, T.; et al. (2009). "Identification of putative expansin-like genes from the pine wood nematode, Bursaphelenchus xylophilus, and evolution of the expansin gene family within the Nematoda" (PDF). Nematology 11 (3): 355–64. doi:10.1163/156854109x446953.
3. Han, H.; et al. (2009). "First report of Bursaphelenchus pinophilus on Korean pine (Pinus koraiensis)". Plant Disease 93 (12): 1354. doi:10.1094/pdis-93-12-1354c.
4. Shinya, Ryoji,; et al. (2014). "Evidence of Hermaphroditism and Sex Ratio Distortion in the Fungal Feeding Nematode Bursaphelenchus okinawaensis". G3 4 (10): 1907–17. doi:10.1534/g3.114.012385. PMC 4199697. PMID 25122669.
5. Ryss, A.; et al. (2005). "A synopsis of the genus Bursaphelenchus Fuchs, 1937 (Aphelenchida: Parasitaphelenchidae) with keys to species" (PDF). Nematology 7 (3): 393–458. doi:10.1163/156854105774355581.