Arthropod diversity in rice ecosystem with special reference to spiders in mid-hills od Meghalaya
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Date
2019
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College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University-Imphal
Abstract
Biodiversity is essential for sustainability of life on Earth. Terrestrial arthropods represent maximum proportion of all biotic diversity in the world. Spiders are diverse arthropods attaining seventh rank in diversity. In rice ecosystem, spider plays an important role as predators in reducing plant hoppers and leafhoppers. Biological control of insect pests through spiders is gaining importance as they are efficient in reducing pest population and also reduce the use of toxic chemical pesticides. The present study was undertaken to document diversity of arthropods in rice field. A total of 1640 individuals which come under 98 species belonging to 74 genera from 37 families represented by 9 orders falling under 2 classes viz., Arachnida and Insecta were recorded during the study period. Arthropods were collected using various methods viz., visual search, net sweeping, pitfall and rubbish trapping and use of aspirator. Of the total number of individuals collected, class Insecta formed the major group with 909 individuals, while 731 individuals were represented by class Arachnida. Under Arachnida, 41 species from 23 genera and 10 families were identified. Among the Pterygota, Exopterygota formed the largest group with majority of individuals from Hemiptera followed by Orthoptera, Odonata and Dictyoptera. Endopterygota was represented by four orders viz., Lepidoptera, Hymenoptera, Coleoptera and Diptera. In the order Araneae, Araneidae was the most dominant family represented by 6 genera with 16 number of species, followed by the family Lycosidae represented by 2 genera with 4 number of species. Data analysis based on species richness and abundance revealed that October month showed maximum index value in all the indices. A guild structure analysis of spiders revealed six feeding guilds such as orb web weavers, stalkers, ground runners, space web builders, ambushers and foliage runners. Orb weavers guild was shown as the most dominant guild which was abundantly found in the month of October when crop canopy was fully developed. Oxyopes bharatae and Pardosa sumatrana were found throughout the study period. Correlation analysis showed that Araneidae population showed positive correlation with rainfall but negatively correlated with maximum temperature and relative humidity.