Nematode Trophic Diversity in the Pristine and Cultivated Fields of Nilgiris using Sedgewick-Rafter Slides

Nematodes are most abundant, diverse and ubiquitous fauna and exist in almost every possible niche in the earth. Due to their omnipresence nematodes are recognized as bio indicators to assess the quality of environment. Such ecological studies on distribution, diversity and dynamics require selection of suitable counting dish and high cost sophisticated stereoscopic microscopes. Although the counting dishes have evolved over time, we propose the usage of Sedgewick-Rafter counting slides, which can be used under the compound microscope and to demonstrate its utility, the nematode trophic diversity analysis was performed for the samples from pristine and cultivated fields of Nilgiris. To the best of our knowledge, this is the first attempt to use Sedgewick-Rafter slide for the nematode diversity analysis in India. The results indicated that the total nematode population was higher in fields with garlic followed by carrot, wheat, potato and kurinji, whereas the nematode trophic diversity was high in wheat followed by carrot, potato, kurinji and garlic. The plant-parasitic nematode Paratylenchus spp. dominated the cultivated field with garlic, carrot and kurinji, while the Rhabditids dominated the wheat and potato fields. Sample collected from the kurinji had very low nematode population despite their pristine habitat. We found that the wheat crop is one of the best crops among the annual crops for the Nilgiris in supporting the soil biodiversity. Further, the use of sedgewick rafter slide under compound microscope with 10x objective helped to carry out the identification and precise quantification simultaneously.