Current World Environment

Introduction

Earthworms are incredibly interesting animals that are essential to all terrestrial ecosystems. They belong to the class Clitellata of the phylum Annelida, and their lengthy and segmented body is frequently connected to their habit of burrowing in soil. They have been on our planet earth for more than 600 million years.1 Sir Charles Darwin conducted the pioneering research during 1881 and referred them to be “the farmer's friend.” Cleopatra in 50 BC was first recognised its importance and proclaimed them as vital. Famous Greek philosopher Aristotle (384–322 BC) was considered that, the earthworms as the “intestine of the earth." This was due to their role in turning over soil from the earth’s depths. 2

While most earthworms prefer their natural habitats, some exotic species that are widely distributed have been successfully introduced into various agro-ecosystems.3 The success of exotic species in colonizing nearly all of India's agroclimatic zones can be attributed to their innate resistance to disruption and interference. Their distribution has been divided into several zones in the country, including mega diversity, high diversity, medium diversity, low diversity, and poor diversity zones.4 Some widely distributed native peregrine species are able to tolerate disturbed conditions. Epigeic, endogeic, and anecic earthworm ecological types are among those that have been recognised.5 

Earthworms are considered as fundamental organisms; because, they perform a broad range of functions in the entire ecosystem.6 These included composition of soil organic matter, releasing of plant nutrients into soil, and in turn allowing water infiltration and percolation in the soil profile.7 It has piqued scientists’ interest in exploring the vast resource of worm diversity. They have been dubbed the major ecological engineers due to their significance to the ecosystem.8 In addition, they are regarded as the most valuable biological resources in agro-ecosystems because of their significant effects on the physical structures of the soil, the dynamics of organic matter, and the promotion of plant growth.9,10 Many biotic and abiotic elements influence the biodiversity and distribution patterns of various earthworm species, such as soil properties, surface vegetation dynamics, local or regional climate, and other human-related activities.11,12

On Global basis, according to published data, around 7000 species of earthworms have been described 13 of which only 3000-3500 species were regarded legitimate and around 150 species are classified as peregrine.14 Many studies on the diversity have been piled by numerous researchers around the world.15 Robert Templeton, a British biologist, pioneered earthworm research in the Indian subcontinent.22,23 World-famous researchers like G. E. Gates, John Stephenson, and Wilhelm Michaelsen rendered significant improvements to the field of oligochaeta between 1901 and 1947.16,17,18,19,20 India accounts for 11.1% of the world's total earthworm variety.21 As of now, the earthworm fauna of India comprises about 457 species spanning across 73 genera and 09 families.44 Earthworm studies in Karnataka state started by Michaelsen (1910) followed by several workers.24.25,26,27,28 There are close to 130 recognised varieties of earthworms in Karnataka.44 An overview of earthworms from the regions of Hyderabad, Karnataka, Gulbarga, Udupi, in addition Dakshina Kannada was noticed.29,30,31,33,34,35,36,45,46

To the maximum extent of my knowledge, no reports reside describing the geographical dispersion structure, diversity, and community structure of earthworms across Pandavapura. Only limited data have been available on diversity, species distribution and abundance of earthworm species in different regions of Karnataka, India. Pandavapura is the integral part of the agricultural area of the state. The latest investigation was made to explore the diversity of earthworms in the aforementioned field because there was a dearth of scientific information over the earthworm fauna in the area.

Material and Methods

Description of Sampling Location: Pandavapura Taluk (12°29'22"N and 76°40'40"E) is a region located in the Mandya District, Karnataka, India (Figure 1). The sampling sites were broadly divided into residential, agricultural and industrial land use types. The major plants in the residential area include Cocus nucifera (Coconut), Musa sp. (Banana), Tectona grandis (Teak), Mangifera indica (Mango), Artocarpus heterophyllus (Jack fruit), Tamarindus indica (Tamarind), Psidium guajava (Common guava) and Carica papaya (Papaya). The agricultural area crops like Saccharum officinarum (Sugar cane) Oryza sativa (Paddy), Cocus nucifera (Coconut), Eleusine coracana (Ragi) and in the industrial land use consisting of the sugarcane crushing and Jaggery industries. The soils of Pandavapura taluk can be grouped in to three important categories, red sandy loam soil, red clay loam soil & gravel mixed red soil. Water bodies like Cauvery River basin, Visveswaraya canal, Lakes, Ponds and Bore wells were also observed in study area.

Figure 1: Study area map   Click here to view Figure

Sample collection and preservation

Beginning with July 2021 to June 2023, a monthly earthworm survey was executed in the chosen agricultural, residential, and industrial land use system of Pandavapura taluk in the Mandya district of Karnataka, India. Based on the accessibility and availability of earthworms, sampling points were decided across the study area. Digging and manual sorting were the methods employed collect the worms.37 Further, adult worms was collected to examine the species.  After being meticulously washed with tap water, the adult worms were placed in a petri dish, narcotized (adding 30% ethyl alcohol), straightened, and fixed in 5% formalin. Under a stereo-zoom binocular microscope anatomical details were examined using reputable references, the species was identified.37,38,39 The application PAST (version 4.03), was employed for interpreting the acquired data for Ecological diversity indices.

Results and Discussion

The current study's findings indicate that 11 earthworm species from 06 families have been found in various locations throughout Pandavapura Taluk. (Table 1) (Figure 2). The reported species are Drawida modesta; Drawida nepalensis; Pontoscolex corethrurus; Eudrilus eugeniae; Eutyphoeus orientalis; Eisenia fetida; Perionyx excavates; Metaphire anomala; Metaphire posthuma; Lampito mauritii; Amynthas alexandri, (Table 2a and 2b). Further, Megascolecidae is the most dominant family represented by five species followed by Moniligastridae with two species and Rhinodrilidae, Eudrilidae, Acanthodrilidae and Lumbricidae families with one species each and their occurrence is depicted in Table 3. 

Table 1: Species List of Earthworms Collected from Various Habitats in Pandavapura Taluk, Mandya district, Karnataka.

Table 2a: Taxonomic characters of the Earthworm species from Pandavapura taluk of Mandya district, Karnataka

Table 2b: Taxonomic characters of the Earthworm species from Pandavapura taluk of Mandya district, Karnataka

Figure 2: Photographs of collected earthworm species from Pandavapura taluk Mandya district of Karnataka, India.   Click here to view Figure

Table 3: Occurrence of collected earthworm species in the study area.

(-) = Absent; (++) = High Population (20-40 Worms/Unit area); (+) = Low population (10-20) Worms/Unit area.

While the Indian earthworm fauna’s high endemism-represents, roughly 89% of species and 71% of genera.40 However, in the current study exotic peregrine species predominate over native species. Among the recorded earthworm species, 04 are native peregrine, 06 exotic peregrine, 01 Subendemic. Further, the species identified in this study were belong to endogeic and epigenic ecological category (Table. 4). which have a very important role in soil nutrient dynamics.41 Metaphire anomala, Metaphire posthuma and Amynthas alexandri are Exotic peregrine. Generally, Eisenia fetida and Perionyx excavates were the most eurytopic species occurring in present study. Among lesser eurytopic species, Eutyphoeus orientalis in agricultural area and Amynthas alexandri was found in Residential area; Drawida modesta, Metaphire anomala and Lampito mauritii was recorded from residential and industrial habitats; Drawida nepalensis and Eudrilus eugeniae occurred in agricultural and residential fields. Metaphire posthuma are restricted to residential area. Pontoscolex corethrurus is present in agricultural and industrial habitats (Table 3). In existing study exotic peregrine species were widespread in agricultural and residential area whereas native species were restricted to residential and industrial area. These native peregrine species are possibly transported to this area through the soil around roots of exotic plants and other means.41 The altering of habitat and available resources and biological invasion competes or replace the native species.42 Though, the current research is pioneer work from Pandavapura taluk of Mandya district, Karnataka. Recently, similar results have been reported in different parts of India and Karnataka.43

Table 4: List of Ecological group and Zoogeographical distribution of Earthworm Species collected Study area

Ecological diversity indices were calculated using PAST software version 4.03. for the observed species of earthworm. Species richness, evenness and dominance were analysed using Shanon-Shimpson diversity index (Shannon H’ Log Base 10), Simpson diversity index (1/D) and Berger-Parker Dominance (d) index, (Table 5). The Shannon diversity index and Simpson’s diversity index values shows the highest abundance and diversity of earthworms in the Agricultural areas (2.217) than in industrial sites with lowest value (1.993). Generally, high moisture content in the soil favours the growth and abundance of earthworms. In the present investigation, the agricultural area has more moisture content than the industrial area, because the agriculture area in Pandavapura is situated near to the Cauvery River basin, Visveswaraya canal, Lakes, Ponds and Bore wells might be the reason for highest abundance and diversity of earthworms. Similarly, Margaleff M Base 10 index depicts the highest diversity values (1.679) in Agricultural area and lowest (1.534) in industrial area. Further, in the present investigation, more common and abundant species of earthworms are documented in the agricultural habitat followed by the residential and industrial habitats. 

Table 5: Diversity Indices of Earthworm species recorded at Pandavapura taluk, Mandya district, Karnataka.

Furthermore, we strongly suggest undertaking long-term studies on earthworm diversity in order to discover their spatiotemporal distribution and the effects of various land use systems, based on the results of this current research. The significance of different land use systems within the region is highlighted by the variety of earthworm species found in Pandavapura Taluk. The aforementioned results illuminate the need for land use specific approaches to strengthen soil health and sustainable utilise of earthworms, which has implications for land management practices.

Conclusion

Earthworm diversity and abundance were evaluated in three different land use systems of Pandavapura taluk of Mandya District. Totally eleven earthworm species belonging to six families were recorded. Eudrilus eugeniae, Eisenia fetida and Perionyx excavates are the earthworm species which is suggested as the best one for agriculture and vermicompost purpose. The local earthworm species composition may be explained by ecological factors, species-specific dispersal patterns, and dietary preferences. Certain species high abundances can be used as indicators species. In this current investigation the greatest diversity of earthworms is recorded in agricultural area as compared to other land use types. So that, it is important to assess their diversity in order to make informed decisions about environmental management and conservation of sensitive and sentinel earthworm species.

Acknowledgements

Authors are thankful to the Principal of Yuvaraja’s College, University of Mysore, Mysuru and Dr. C. K. Mandal, Scientist-C, Zoological survey of India, who helped in identification and authentication of earthworm species, and also for the reviewers for their valuable suggestions on our manuscript. 

Funding Sources

The author(s) received no financial support for the research, authorship, and/or publication of this article. 

Conflict of Interest 

The author(s) declares no conflict of interest.

Authors’ Contribution

Shashank K R: Writing- Original draft; Conducted experiments; Methodology; Designed the study; Investigation; Data curation; Analysed data. M. Mahadevaswamy:  Formal analysis; Conceptualization; Review and editing; Supervision and Validation.  Both authors read and approved the final manuscript.

Data Availability Statement

The manuscript incorporates all datasets produced or examined throughout this research study.

Ethical approval statement

Not applicable.

References

1. Sinha R.K., Earthworms: The Miracle of Nature (Charles Darwin's unheralded soldiers of mankind and farmer's friends'). Environmentalist.2009;29:339–340.doi: 10.1007/s10669-009-9242-4
   CrossRef
2. Oommen S. K., Studies on Bioprocess of Organic solid wastes applying Vermitech and the efficiency of vermicompost and vermiwash in soil fertility. Kerala: Mahatma Gandhi University, Ph.D. dissertation, 1998;110.
3. Deepthi M. P., Kathireswari P. Earthworm Diversity and Analysis of Soil Inhabited by Earthworms in the Vatakara area, Kozhikode, Kerala, India. Inter Jour Curr Microbiol App Sci. 2016; 5(3): 917-925. doi: http://dx.doi.org/10.20546/ijcmas.2016.503.106.
4. Julka J. M. The fauna of India and adjacent countries. Megadrile Oligochaeta (Earthworms). Haplotaxida: Lumbricina: Megascolecoidea: Octochaetidae. Records of the Zoological Survey of India.1988;400.
5. Blakemore R. J. Cosmopolitan earthworms – an eco-taxonomic guide to the peregrine species of the world, 5th edn. Verm Ecology Solutions, Yokohama. Japan. 2012; 350-850.
6. Bohlen P. J., Scheu S., Hale C., McLean M. A., Migge S., Groff man P. M., Parkinson D. Non?native invasive earthworms as agents of change in northern temperate forests. Frontiers in Ecology and the Environment. 2004; 2(8): 427–435. https://doi.org/10.1890/1540- 9295(2004)002042: nieaao2.0.co;2
   CrossRef
7. Reynolds J. W. Earthworms of the world. Global Biodiversity. 1994a; 4(1): 11–16.
8. Lavelle P., Bignell D., Lepage M., Wolters V., Roger P., Ineson P., Heal O.W., Dhillion S. Soil function in a changing world: the role of invertebrate ecosystem engineers. European Journal of Soil Biology. 1997; 33:159–193.
9. Lavelle E., Barois., Martin I., Zaidi A., Schaefer Z. Management of Earthworm Populations in Agro-ecosystems: A possible way to maintain soil quality. In: Clarholm, M. and Bergstrom, L. (eds.). Ecology of Arable Land: Perspectives and Pathma and Sakthivel. Springer Plus, Kluwer Academic Publishers. London.1989;109–122.
   CrossRef
10. Lee K. E. Earthworms: Their Ecology and Relationships with soils and land use. Academic press. New York, 1985; 411.
11. Narayanan P., Sathrumithra S., Christopher G., Thomas A. P., Julka J. M. Checklist of the earthworms (Oligochaeta) of Kerala, a constituent of Western Ghats biodiversity hotspot, India. Zoo taxa. 2016a; 4193(1): 117–137. 
    CrossRef
12. Suthar S. Earthworm biodiversity in western arid and semiarid lands of India. Environmentalist. 2011;31: 74-86.
    CrossRef
13. Reynolds J.W., Wetzel M. J. Nomenclatura Oligo Chaetologica- A catalogue of names, descriptions and type specimens. Edition Secunda. 2021. http://www.inhs.illinois edu/people/mjwetzel/nomenoligo.
14. Csuzdi C. S. Earthworm species, a searchable database. Opusc. Zool. Budapest. 2012; 43(1): 97–99.
15. Bora S., Bisht S. S., Reynolds J.W. Global diversity of earthworms in various countries and continents: a short review. Megadrilogica. 2021;26(9):127–154.
    CrossRef
16. Gates G. E. On some Indian earthworms. Proceedings of the Indian Academy of Science 1945; 21:208–258. http://www.ias.ac.in/j_archive/procb/21/4/208-258/viewpage.html
    CrossRef
17. Sinha R. K., Heart S., Agarwal S., Asadi R., Carretero E. Vermiculture technology for environmental management: Study of the action of the earthworms Eisenia foetida, Eudrilus euginae and Perionyx excavatus on bio-degradation of some community wastes in India and Australia. The Environmentalist. 2002;22: 261–268.
    CrossRef
18. Tripathi G., Bharadwaj P. Earthworm diversity and habitat preferences in arid regions of Rajasthan. Zoo's Print Journal. 2004;17(7): 1515-1519.
    CrossRef
19. Sharma R. K., Poonam B. Earthworm diversity in Trans-gangetic habitats of Haryana. Research Journal of Agriculture and Forestry Sciences. 2014; 2(2): 1-7.
20. Goswami R., Mondal C. K. A study on earthworm population and diversity with special reference to physico-chemical parameters in different habitats of South 24 Parganas district in West Bengal. Records of the Zoological Survey of India. 2015; 115: 31-38.
21. Julka J. M., Paliwal R. Annelida: Oligochaeta. In: Fauna of western Himalaya, Part 2. Zoological Survey of India Kolkata. 2005;53–60.
22. Kathireswari P. DNA Barcoding of Earthworms. International Science Communicators meet. 2016; (103rd ISCA, Mysore).
23. Ahmed S., Julka J. M. First record of exotic earthworm, Amynthas hupiensis (Michaelsen, 1895) (Oligochaeta: Megascolecidae), from India. Megadrilogica. 2017; 22(7): 151–154. http://www.inhs.uiuc.edu/~mjwetzel/Megadrilogica.home.html.
24. Kale R. D., Krishnamoorthy R.V. Distribution and abundance of earthworms in Bangalore. Proceedings of the Indian Academy of Science (Animal Science) Section B. 1978;87(3): 23–25.
    CrossRef
25. Krishnamurthy R.V., Ramachandra S. Population structure of earthworms in woodlands of Karnataka. Proceedings of the Indian Academy of Science (Animal Science) Section B. 1988; 97(4):355–365.
    CrossRef
26. Blanchart E., Julka J. M. Influence of forest disturbance on earthworm (Oligochaeta) communities in the Western Ghats (South India). Soil biology and Biochemistry. 1997; 29(3/4): 303–306.
    CrossRef
27. Rao B. R. C. Studies on the biological and ecological aspects of certain Indian earthworms. Karnataka. Ph. D. Dissertation, Mysore University. Mysore, India. 1979; 242.
28. Julka J.W., Blanchart E., Chapuis L. New genera and new species of earthworms (Oligochaeta: Octochaetidae) from Western Ghats, South India. Zoo taxa. 2004; 486: 1–27.
    CrossRef
29. Siddaraju M., Sreepada K. S., Reynolds J. W. Checklist of earthworms (Annelida: Oligochaeta) from Dakshina Kannada, Karnataka South-West Coast of India. Megadrilogica. 2010; 14 (5): 65–75.
30. Siddaraju M. Earthworm species diversity in Dakshina Kannada District and organic waste management through vermitechnology. Ph.D. thesis, Mangalore University, Karnataka, India. 2011; 173.
31. Siddaraju M., Sreepada K. S., Krishna M. P. Recorded distribution of earthworms of the family Octochaetidae in Dakshina Kannada district, South-West coast, Karnataka. International Scientific and Research Publication. 2013; 3(6): 2250–3153.
32. Hegde P. R., Sreepada K. S. Freshwater Oligochaetes (Annelida) from Western Ghats and the West coast of Karnataka (India). Turkish Journal of Zoology. 2015; 39: 523–526.
    CrossRef
33. Hatti S. S. Taxonomical studies on earthworm species of Gulbarga city, Karnataka, India. Indian Journal of Applied Research. 2013;3(7):34–38.
    CrossRef
34. Padashetty S., Jadesh M. A preliminary survey of earthworm species composition and distribution in the North Karnataka region, Gulbarga, Karnataka. International Letters of Natural Sciences. 2014;27: 54–60.
    CrossRef
35. Harish Kumar T. S., Sreepada K. S., Narayanan S. P., Reynolds J. W. Checklist of megadrile earthworms (Annelida: Oligochaeta) around Udupi Power Corporation Limited (UPCL), Udupi District, Karnataka, South-West Coast of India. Megadrilogica. 2018a ;23(5): 79-89.
36. Mubeen H., Hatti S. S. Earthworms diversity of Koppal district with the updated information on genus Thatonia of Hyderabad Karnataka region, Karnataka, India. Journal of Asia-Paci?c Biodiversity. 2018. https://doi.org/10.1016/j.japb.2018.08.002
    CrossRef
37. Julka J. M. The fauna of India and adjacent countries. Megadrile Oligochaeta (Earthworms). Haplotaxida: Lumbricina: Megascolecoidea: Octochaetidae. Records of Zoological survey of India. 1988; 400.
38. Stephenson J. The Fauna of British India including Ceylon and Burma- Oligochaeta. Taylor and Francis. London. 1923; 518.
39. Gates G. E. Burmese earthworms, an introduction to the systematic and biology of the megadrile oligochaetes with special reference to Southeast Asia. Transactions of the American Philosophical Society. 1972; 62(7): 1–326.
    CrossRef
40. Julka J. M., Paliwal R., Kathireswari P. Biodiversity of Indian Earthworms – An Overview. Proceedings of the International workshop on Vermi technology in Human Welfare, Departments of Zoology and Biochemistry, Kongunadu Arts and Science College, Coimbatore, Tamil Nadu, India. 4th–7th June 2007: 18–37.
41. Julka J. M. Distribution of earthworms in different agroclimatic regions of India. Workshop on tropical Soil Biology and Fertility programme. School of Environmental Sciences. J N U, New Delhi. 2001; 1- 12.
42. Vitousek P. M. Biological invasions and ecosystem processes: toward an integration of population biology and ecosystem studies. Oikos. 1990;57: 7–13.
    CrossRef
43. Harish Kumar T. S., Siddaraju M., Bhat C. H. K., Sreepada K. S. Seasonal distribution and abundance of earthworms (Annelida: Oligochaeta) in relation to the edaphic factors around Udupi Power Corporation Limited (UPCL), Udupi District, South-western Coast of India. Journal of Threatened Taxa. 2018; 10(3): 11432–11442; http://doi.org/10.11609/jott.3806.10.3.11432-11442.
    CrossRef
44. Narayanan, S.P., Paliwal, R., Kurien, V.T., Thomas, A.P. & Julka, J.M. Earthworms (Clitellata; Moniligastrida, Crassiclitellata) of India: Distribution and Status, 1st Edition. Department of Printing and Publishing, Mahatma Gandhi University, Kottayam. 2023; 1–378.
    CrossRef
45. Hasyagar, V., Narayanan, S.P., Sreepada, K.S. & Reynolds, J.W. Amynthas alexandri Beddard, 1901 (Clitellata: Megascolecidae) a new addition to the earthworm fauna of Karnataka state, southern India. Megadrilogica. 2021; 26(3): 43–48.
46. Hasyagar, V., S.P. Narayanan & K.S. Sreepada. Range extension of earthworm Drawida impertusa Stephenson, 1920 (Clitellata: Moniligastridae) in Karnataka state, India. Journal of Threatened Taxa. 2022; 14(6): 21307–21310. htps://doi.org/10.11609/jot.7630.14.6.21307-21310
    CrossRef