khu hệ giun đất ở đồng bằng sông cửu long, việt nam bản tóm tắt tiếng anh

To study the species richness, establish catalogue, analyze fauna characteristics, build keys and determined therelationship of some species earthworms in The Mekong Delta... PRACTICAL A

INTRODUCTION

1 THE IMPORTANCE OF PROBLEM

Earthworms are soil invertebrates appeared on the Earth 600 million years ago Most members of the Earthworms areterrestrial and least semi-aquatic They belong to class Oligochaeta of phylum Annelida (Edwards & Bohlen, 1996)

Earthworms play the important roles in soil physical, chemical, and biological characters The earthworms have highprotein, so they are suitable as feed for fish, poultry and cattle In the folk medicine of our country and many countriesaround the world, earthworms are used to treat certain diseases such as malaria, smallpox, asthma, arthritis, epilepsy,jaundice, stones in the bladder, They are also indicators of change, the origin of a regional soil and soil characteristics.Earthworms also hold an important position in the evolution of animals from water to land, that can help us visualize theformation of species, subspecies and evolution of the system of animal organs In addition, some earthworms are

intermediate hosts of some parasitic nematodes such as Metastrongylus, Stephanurus dentatus (Thai Tran Bai, 1983, 1989; Edwards, 2004; Georgescu et al., 2011).

In Vietnam, earthworms are one of the groups of animals were studied very early (Perrier, 1872, 1875) So far, theresearch earthworm fauna in North and Central have nearly completed but only a few studies in The Mekong Delta

Therefore, we will study “The Earthworm fauna of The Mekong Delta, Viet Nam”

2 RESEARCH OBJECTIVES

1 To study the species richness, establish catalogue, analyze fauna characteristics, build keys and determined therelationship of some species earthworms in The Mekong Delta

2 To study on distribution characteristics of earthworms in different topography types, biotypes, seasons and stratums(depths) in the study area.

3 To survey on use of the earthworms in The Mekong Delta and to suggest the direction for the exploitation and usethem in the future

3 SCOPE AND LIMITATIONS

This study was conducted at The Mekong Delta, not including the islands in the sea The data in this PhD thesis aresummarized on the basis of the research from 2009 to 2011 and inherited from the master thesis myself (from 2007 to 2008)

This study has used a classification system of Kinberg (1867) for Pheretima genus, to wait for a new classification system

more satisfactory

4 PRACTICAL AND SCIENTIFIC SIGNIFICANCE OF RESEARCH

This study will provide fully and accurately about species composition and distribution characteristics of earthworms

of The Mekong Delta that contributes to complete the earthworm fauna of Vietnam It will provide data about faunacharacteristics, and key to the species of earthworms in The Mekong Delta, that serves well for teaching and scientificresearch in the future

This study will provide an overview of the use and actual needs On the basis, that will be the exact orientation for theexploitation and use of earthworms in the Mekong Delta

This research will provide data about copulatory pouches and molecular biology (DNA barcode) of some earthworms

of genus Pheretima that is a useful source of information to rebuild the classification system for this species group in the

future

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CHAPTER 1: LITERATURE REVIEW1.1 RESEARCH SITUATION OF EARTHWORM FAUNA IN THE WORLD

Studies on earthworm fauna have been performed widely in many countries and territories worldwide According toBlakemore (2002), the earthworm fauna of Europe and North America have been researched the most complete, followed bythe Australian of earthworm fauna, the Asia of earthworms fauna have also been researched by many authors, especiallySoutheast Asia, but the fanua earthworms of Africa are still little known

Particularly in Southeast Asia, there are also many researches on the earthworm fauna but not uniform in all countries.Diversity of species and the authors studied earthworms in some neighboring countries of Vietnam are summarized in table2.1

Table 2.1: Diversity of species and the authors studied earthworms of some neighboring countries of Vietnam.

Gates (1935a, 1935b), Huang & et al (2007),…

(2007), Somniyam (2008), Bantaowong & et al (2011),…

Hong (2008), Inkavilay et al (2009) và Chanabun et al (2011),…

1.1 RESEARCH SITUATION OF EARTHWORM FAUNA IN VIETNAM

The earthworm fauna of Vietnam was started to research in the late 19th century by Perrier (1872, 1875) Until the early

20th century, there were more some works of foreign authors Stephenson (1931) published two new science species whichwere collected in the Langbiang Plateau Michaelsen (1934) presented sixteen species which were found in Da Lat, QuyNhon, Da Nang, Phu Quoc Island, Phu Tho, and then is the research of Omodeo (1956) Overall, these works are scattered,where researchers are often the cities and tourist destinations in the Southern Vietnam

From 1965 to 1975, the study of earthworms was interrupted by war, and was only conducted limited in some areas.The collected data was morphology and ecology of several widely distributed species to service for teaching (Thai Tran Bai,1983)

Since 1979, the earthworm fauna of Vietnam has been studied widely and systematically The first was the PhD.Thesis of Thai Tran Bai (1983) “Earthworm of Vietnam (Systematic, Fauna, Distribution and Zoogeographic)” The results

of this study show that there are 109 species and subspecies, belonging to 6 families and 17 genera for the earthworm fauna

of Vietnam Among of them there are 39 species and subspecies new for science Then, he guided several PhD thesis on theearthworm fauna in Vietnam (table 2.2)

Table 2.2: The author, location, research results of 6 Ph D theses on the fauna earthworms of Vietnam.

species*

Species* Genus Family

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1995 Le Van Trien Northeastern 72 11 5 5

* species and subspecies

According to Thai Tran Bai (2000b) and updated, so far the earthworm fauna of Vietnam has been found 204 speciesand subspecies, 18 genara, of 7 families Among them, Family Megascolecidae has most various species with 181 speciesand subspecies, followed by Ocnerodrilidae (7 species), Octochaetidae (6 species), Moniligastridae (5 species), Lumbricidae(2 species) and 2 remaining families (Glossoscolecidae, Microchaetidae) with 1 species of each There are 25 species ofearthworms and many taxa not identified the scientific name in the South of Vietnam In particular, the Mekong Delta

mainland only recorded 14 species of earthworms, belonging to 8 genera, 5 families and a few taxon of the genus Pheretima and Drawida not be identified to species.

Most the earthworm sampling points in Vietnam is shown in Figure 1.1, through which to see the sampling points areconcentrated in the North and Central of Vietnam, The earthworm fauna of Southern has been little studied In addition, thesample concentrated mainly in the plain, less than in the hills and very few in the islands

Figure 1.1: The sampling earthworms in Vietnam

(According to Stephenson (1931), Michaelsen (1934b), Omodeo (1956), Thai Tran Bai (1983), Tran Thuy Mui (1985), Do Van Nhuong (1994), Nguyen Van Thuan (1994), Le Van Trien (1995), Pham Thi Hong Ha (1995), Huynh Thi Kim Hoi (2005), Nguyen Thanh Tung (2008), Nguyen Van Thuan and Nguyen Thi My Hang (2010), )

CHAPTER 2 LOCATION, TIME, MATERIALS AND METHODS RESEARCH

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2.1 LOCATION AND TIME RESEARCH

Based on the differences in the impact of hydrology and soil properties (mechanical composition, pH and salinity), the earthworm sampling points in the Mekong Delta are arranged in 4 topographies: mountainous, river alluvial plains,

down warping far from the river basin and coastal mixed According to Thai Tran Bai (1983), the Mekong Delta is divided

into biotypes: natural forest, planted forest, mango gardens at the foot of the mountains, wilderness, the edge of the river orpond, perennial garden, short-day crops garden and livestock

A total of 187 sampling points were collected of 13 provinces and cities in the Mekong Delta The sampling pointsconcentrated in the Tien and Hau River basin, less than down warping far from the river of Dong Thap Muoi, Long XuyenQuadrangle and Ca Mau Peninsula for flooded during the year (Figure 2.4)

Earthworm samples were collected quantitatively and qualitatively from 2007 to 2011 Each year collected in twodifferent seasons: the dry season from January to June, rainy season from July to December, but focus on October andNovember is the time of many earthworms has more mature individual (especially in the mountains)

2.2 MATERIALS AND METHODS RESEARCH

2.2.1 Materials

This study was based on analysis of 2,868 individuals earthworms, of which 15,447 individuals collected in 1,109quantitative pit The sample is hold at the Laboratory Animals, Can Tho University and Soil Organism Research Center,Hanoi National University of Education

Tools and equipment include canvas bags, paper label, measure, GPS (Garmin, Japan), electronic balance (accuracy0.01 g), microscope and surgical kits, and more instruments and apparatus for DNA extracted and sequenced

Chemical fixed earthworms of 2% formaldehyde, formaldehyde 4%, alcohol 96% In experiments extracted andsequenced using a variety of different chemicals and primers LCO1490, HCO2198, COI-E to PCR the DNA barcode.

Morphological - ecological groups of earthworm were divided by Thai Tran Bai (1983) The origin and dispersal of themajor terrestrial earthworm families was determined by Hendrix et al (2008) Oriental divided into two regions and the

provinces on the basis of Thai Tran Bai (1983) The close species composition between the faunas and Radulescu (1961).The close species composition between the earthworm fauna in the Mekong Delta with other fauna calculated as of Stugrenand Radulescu (1961) Diversity index was calculated according to Shannon and Weiner (1963) and "Eveness index"according to Pielou (1966)

Taxonomic relationships of earthworm species in the Mekong Delta was determined by morphological characteristicsusing numerical phenetics and Cladistics methods based on DNA barcode sequences

CHAPTER 3: RESULTS AND DISCUSSION3.1 THE EARTHWORM FAUNA OF THE MEKONG DELTA

3.1.1 Checklist earthworm of the Mekong Delta

Table 3.1: List and frequency of earthworms in the different topography of the Mekong Delta

MEGASCOLECIDAE (part Rosa, 1891)

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9. Pheretima peguana Rosa 1889 0.38 0.09 0.16 0.13

33. Gordiodrilus elegans Beddard, 1892 0.20 0.05

3.1.3 Property of the fauna earthworm in the Mekong Delta

3.1.3.1 Species composition structure

So far, there have been recorded 34 species of earthworms, belonging to 9genus, 6 families in the Mekong Delta In particular, two new species for science

(Ph thaii and Ph mangophila), 1 new species for Vietnam (Drawida barwelli), 3 new species were found the first in the study area (Ph anomala, Ph californica and Ph taprobanae) and 14 taxa are new species waiting publication.

Genus Pheretima has 24 species (70.58%) dominate absolutely which was

consistent with the nature of the earthworm fauna of Indochina, was the original

distribution of the genus Pheretima Next, Drawida has 3 species (8.82%), the

majority of these species in common in India - Malaysia but the distribution of

them including Vietnam The remaining genera (Pontoscolex, Lampito, Perionyx, Pontodrilus, Glyphidrilus, Gordiodrilus and Dichogaster) each have one species,

accounting for 2.94%

In Pheretima genus, three species of the acoecata group, accounting for

8.82%, this rate is lower than the Quang Nam - Da Nang and South Central buthigher superior to the other fauna have been studied in our country With 21species of the coecata group, there are 3 species groups related to the Mekong

River Basin: posthuma species group (including 2 species: Ph posthuma, Ph juliani), houlleti species group (including 4 species: Ph houlleti, Ph sp.8, Ph thaii and Ph mangophila), especially peguana species group with 2 known species Ph bahli and Ph peguana has discovered 5 new species is Ph sp 4, Ph.

sp 9, Ph sp 11, Ph sp 14, Ph sp.15, Therefore, it is possible to predict the

Mekong Delta is the homeland for this species group From the data on

morphological, histological structure and molecular biology shows that Ph pacseana not belonging to peguana species group.

Based on frequency of the earthworm species in the Mekong Delta is

divided into three different groups: common group 1 species 2.94% (Pontoscolex corethrurus), rare group 4 species 11.76% (including Ph houlleti, Ph posthuma,

Ph sp 8, Ph elongata), the remaining 29 species (85.94%) were classified as random By Thai Tran Bai (1987), Ph bahli background species in the Mekong

Delta, but the frequency of this species (C = 21%) is lower than some otherspecies in the study area.

According to the division of the Thai Tran Bai (1983) about morphological groups, the earthworm of the Mekong Delta was divided into 3groups Litter group at least, there are three species accounted for 8.82%

eco-(Perionyx excavatus, and Ph thaii and Ph mangophila) Next, mainly soil group has 15 species accounted for 44.12% (Ph elongata, Ph taprobanea, Ph posthuma, Ph sp 5, Ph sp 7, Ph sp 13, Ph sp 15, Ph sp 16, Pontoscolex corethrurus, Pontodrilus litoralis, Dichogaster bolaui, Gordiodrilus elegans, Drawida barwelli, Drawida sp 1 and Drawida sp 2) Soils – litter group with 16

species accounted for 47.06% (all remaining species) This is consistent with thenatural characteristics in the Mekong Delta, a large area of plain human habitatsand forest habitat is concentrated in the high-elevation mountains, often eroded, sothe litter floor relatively small and thin Therefore, the litter a very low percentagecompared to the other systems

3.1.3.2 The relationship of the earthworm fauna of the Mekong Delta with neighboring faunas

There are 12 species in the Mekong Delta were widely distributed all over

the world (Pontoscolex corethrurus, Perionyx excavatus, Drawida barwelli, Ph californica, Ph houlleti, Ph posthuma, Ph elongata, Ph taprobanae, Pontodrilus litoralis, Gordiodrilus elegans, Dichogasterbolaui, Lampito mauritii),

3 species only found in South Asia or Southeast Asia (Glyphidrilus papillatus, Ph bahli and Ph peguana), 2 species only found in Indochina (Ph juliani and Ph sp.

8), the remaining 17 species found in Vietnam or only o in the study area

The earthworm fauna of the Mekong Delta have a relationship fromdifferent to very different with neighboring faunas (R from 0.41 to 0.89).However, this values only was relative becausse of the scope and level ofresearch was different from faunas The earthworm fauna in the Mekong Deltahas 15 species (41.12%) similar with the southern central fauna, 11 species(32.35%) with Binh Tri Thien and Northwest, 10 species (29.41%) with Thailandand Quang Nam - Da Nang, 8 species (23.53%) with the fauna of Laos, Northeast

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