Araneofauna associated with selected horticultural crops of thrissur district, Kerala.

Abstract

Horticulture plays a pivotal role in enhancing the food security in our country through increased production of fruits, vegetables and spices. Spiders in the croplands helps in biocontrol of pests in crop fields and there by alleviate the problem of increased use of agrochemicals and health hazards due their residues in crops. This study was conducted or investigating the diversity of spiders within horticultural ecosystems across five different sites in Thrissur district, Kerala, India. The research spanned two years, from 2016 to 2018, focusing on croplands in Kuzhur, Narayanamangalam, Nenmanikkara, Bharata, and Chelakkara, all located in Thrissur district. 116 species of spiders from 75 genera and 21 families were found from the fields of horticultural crops in the Thrissur district. Salticidae and Araneidae were the predominant families, with Salticidae exhibiting the highest richness, comprising 25 genera and 30 species, followed by Araneidae with 10 genera and 24 species. A noticeable difference in diversity, richness and abundance was observed among the habitat surveyed. Nenmanikkara ranked highest in case of richness and Narayanamangalam in case of abundance. An adequate sampling efficiency was reported as the species accumulation curves approached the plateau. On analysis of seasonal fluctuation of diversity, post monsoon season peaked in richness and abundance while in pre-monsoon season it reached to lowest value. Rank abundance curves for various habitats and seasons were plotted for visual comparison of diversity. Out of the seven feeding guilds reported, other hunters turned to be the dominant one. A preliminary analysis on the impact of two commonly used pesticides; quinalphos and lambda cyhalothrin on four dominant species of spiders, was conducted. It was found that both these pesticides adversely affect the feeding efficacy of all the four species of spiders under study. It was also noteworthy that the impact of lambda cyhalothrin was significantly higher than quinalphos in all the cases.