Comparison of Spider Diversity in Relation to Pesticide Use in Apple Orchards of Kashmir

Abstract

Species diversity, abundance and habitat association of spiders were studied in 9 sprayed and unsprayed apple orchards in Kashmir. Fifty species of spiders were recorded from unsprayed orchards while 46 from sprayed orchards. Total number of species recorded from individual orchards varied from 31-38 in unsprayed orchards and from 20-28 in sprayed orchards. The proportion of web builders, visual hunters and tactile hunters was recorded as 22.32 %, 28.32% and 15.78% respectively in unsprayed orchards while, the corresponding figures for sprayed orchards were appreciably lower viz., 8.84%, 16.96% and 7.78%, respectively. The web building spider families (Theridiidae and Tetragnathidae) were most affected by pesticide application followed by visual hunters (Lycosidae and Salticidae) whereas, the tactile hunters were the least affected with the exception of members of family Thomisidae. The spider species found to be altogether absent from the sprayed orchards, viz., Araneus trifolium Hentz, Hyposigha spp., Zygoballus spp., Thomisus cherapunjeus Tikader constituted very low percentage even in the spider communities that were not under the pesticide application pressure. The sprayed orchards exhibited poor spider diversity and less even distribution of spider taxa while species richness was little affected by pesticide application, the only exception being family Araneidae. The results indicated that pesticide application is posing a serious threat to diversity and richness of spiders in the apple orchards.