Biodiversity And Biogeography Of The Genus Bursaphelenchus Fuchs, 1937 (Nematoda: Parasitaphelenchidae)

Biogeography is the scientific study of the geographic distribution of organisms. It aims to study the earth surface layer biota, reveals the spatial distribution of biodiversity laws and describes the biological quantity and species distribution pattern on the earth. In this dissertation, the biogeography and the plant quarantine was unified. The role of the biogeography in the plant quarantine, the application of biogeography in plant quarantine and pest risk analysis were expounded and discussed.The main objects of the plant quarantine focus on invasive alien pests and the characteristics of geographical distribution of pests. The geographic distribution related to ecological factors (such as climate, host plants and natural enemies) and the proliferation of non-ecological factors (such as pest biology characteristic, transmission and dispersal route). Thus, many such factors are belong to the field of biogeography. Biodiversity and biogeography characters of the genus Bursaphelenchus Fuchs, 1937 were discussed. The main work and innovations in this dissertation are as follows:1. Species diversity and ecological diversity of the genus Bursaphelenchus were elaborated. The taxonomy of Bursaphelenchus spp. was identified during the quarantine of entry-exit wood packaging and the epidemic monitoring process of pin wood nematode. A new species was identified as B. parapinasteri sp. nov. from masson pine (Pinus massoniana). B. fraudulentus, B. fungivorus, B. hylobianum, B. rainulfi, and B. thailandea were reported as new records in China.The identification key to 87 species of Bursaphelenchus spp. was established based on the characteristics of spicule, tail papilla, shape of copulatory bursa of male, vulva epiptygma, postuterine branch, tail shape of female, the whole morphology characteristics and so on. According to morphological characteristics of spicule, the genus Bursaphelenchus was re-individed into 6 groups : B. aberrans group, B. borealis group, B. eidmanni group, B. hunti group, B. piniperdae group and B. xylophilus group. All those results above are based on relevant domestic and international references which were systematically collected, sorted and processed up to 2007 about this genus.In eco-diversity, 87 species of the genus Bursaphelenchus were individed into 4 life-styles according to their host range, transmission, nutrition support methods and niche. Life-styleâ… : 22 species of them were considered as fungal-feeding or free-living Bursaphelenchus spp; Life-styleâ…¡:8 species were defined as entomogenous nematodes; Life-styleâ…¢: There are 55 members transmitting by insect vectors,fungal-feeding or facultative parasite nematodes; Life-styleâ…£:2 species are plant pathogenic nematodes.Life styles reflect a certain relationship of inheritance in ecologically evolutional process between Bursaphelenchus spp. and Aphelenchida nematodes from fungal-feeding and filamentous algae-feeding to entomogenous nematodes and plant pathogenic nematodes.2. Geographical distribution and fauna of the genus Bursaphelenchus in the world were discussed. Based on the geographic distribution of Bursaphelenchus spp., the richness of the genus in different geographic regions and the relationship between species richness and the ecological environment were revealed. Geography species richness are 42 species in Europe, 30 species in Asia, 21 species in North America, 4 species in the Caribbean and Central and South America. According to the relevant domestic and international references, species of Bursaphelenchus spp. of different countries and regions were summarized, countries as distribution spot, species and the quantity of species for attribute value and superimposes on digit world map which provides by GIS software , the world geographical distribution map of Bursaphelenchus spp. was provided.It is intuitive that geographic distribution of the world that all countries are currently exist or found species, expressed species of Bursaphelenchus spp. present in the world, the geographical distribution of the communication sphere. According to ecological distribution and geographic location of the species, the survival environment of Bursaphelenchus spp. and pest risks were provided to plant quarantine. Distribution of zoogeographical regions of the world of Bursaphelenchus spp. was performed.Based on the zonality principle and distribution status of zoogeographical regions and areas adjacent to the status of Bursaphelenchus spp. has been divided into cosmopolitan species, mutual species and endemic species., mutual species and endemic species. The effect of natural dispersal route and artificial dispersal route of Bursaphelenchus spp. was discussed.3. The geographic dispersion law of the genus Bursaphelenchus was summarized.Geographical differentiation of the genus Bursaphelenchus in its origin and dispersion process, reflects the evolution process from fungal-feeding and filamentous algae-feeding to entomogenous nematodes and plant pathogenic nematodes from the preliminary class to high class. It indicted the parallel relationship between geographical extension and species evolution. The species evolution is often contemporaneous with the geographical dispersion.The results also indicated that there was a close relationship between the species origin and ecological niche of Bursaphelenchus spp. Our study showed that the harmonious relationship between species origin location and ecological environment sustains the ecological balance. The Bursaphelenchus spp. as the species in North America has been formed a stable equilibrium to the North America pine with lower threat to North American pine. Once the balance is disrupted, the nematodes as the alien pests enormously spread to new area of pine trees and therefore resulted in considerable destruction.4. The biogeography of B. xylophilus was studied with the disease control in China.Bursaphelenchus xylophilus (Steiner & Buhrer, 1934) Nickle, 1970, was known as a pine wood nematode or pine wilt nematode (PWN), which was the quarantine pest in China and some other countries. The biogeographic characteristics, damage characteristic and quarantine significance of PWN were elaborated. The distribution map was established based on available data.According to the occurrence status of Bursaphelencesus spp. in China, publishing data of distribution status of PWN and the Chinese geography and topographic characteristics, the distribution regional map and potential invasion area in China were planed by using GPS and GIS technology. Thus, the damage degree by PWN was designed as the serious infection ranges (<400 m elevation), medium infection ranges (400-700 m elevation) and incidental occurrence ranges (700-1000 m) in light of altitude.Theoretical geographical occurrence area has individed into 4 types :â‘ severe occurred area,â‘¡mild occurred area,â‘¢incidental occurred area,â‘£safety area. Yangtze River Delta, Pearl River Delta and Taiwan island are consided as pine wilt disease susceptibility centre in China. The above results of biogeography provided a reference for PWN quarantine, monitoring and forecast in China.