Faunistic and diagnostics of predaceous spiders in rice ecosystem under Terai region of West Bengal

Abstract

Aim: Analyzing the community structure of predatory spider fauna in rice ecosystems to facilitate conservation biological control and sustainable pest management programmes. Methodology: The spiders were collected from rice field with cultivated variety (MTU-7029) during both Kharif and Rabi seasons at different rice growth stages. The spiders collected by various sampling methods such as direct catch in polythene carry bags, ground collection and foliage collection were kept in collection bottles and killed by inserting a strip of cotton dipped in chloroform and transferred separately on a white sheet of paper. Thereafter, using a stereo zoom microscope (ZEISS Stemi 508), the spiders were sorted, separated, counted, identified based on the available keys and literature described by Tikader (1987) and Barrion and Litsinger (1995). The unidentified samples were sent to the Zoological Survey of India, Kolkata for authorized identification. Results: In total, sixteen different species of predatory spiders belonging to six families of order Araneae and representing four functional/foraging guilds were identified in the rice ecosystem of Sub-Himalayan Terai region of West Bengal. These included Lycosa pseudoannulata Boesenberg & Strand and Arctosa tanakai Barrion & Litsinger; Oxyopes lineatipes C.L. Koch, Oxyopes javanus Thorell and Oxyopes salticus Hentz; Bianor sp. and Hasarius adansoni Audouin, while the family Thomisidae was represented by a single species Thomisius sp. All these eight species constituted the non web former group of spiders. The web weaving spiders recorded were Tetragnatha maxillosa Thorell, Tetragnatha mandibulata Walckenaer. Tetragnatha javana Thorell, Leucage decorate Walckenaer, Leucage celesbesiana Walckenaer and Neoscona theisi Walckenaer, Neoscona mukerjei Tikader, Araneus sp. Interpretation: The lynx spiders (Oxyopidae) were found to be the most dominant group by individual numbers, followed by the wolf spiders (Lycosidae), however, considering the species richness, the long jawed spiders (Tetragnathidae) were in large number with five different species. Good agricultural practices along with habitat diversification of landscapes are imperative for enhancing the predation by rice field spiders. Key words: Dominance, Foraging guilds, Predatory spiders, Rice, Species richness, Terai region