fauna and population fluctuations of spiders (arthropoda: araneae) in rice fields of mazandaran province

spiders are the powerful and efficient predators in almost all ecosystems which have effective role in different pest control. the fauna of these arthropods was surveyed during 2005-2009, and their population fluctuations and activities were studied in mazandaran paddy fields in 2005-2006. a total of 53 spider species of 44 genera were collected and identified from paddy fields of mazandaran province. of these, five species including, dysdera aculeata kroneberg, harpactea babori (nosek), pardosa hortensis (thorell), pardosa paludicola (clerck) and tedia oxygnatha simon were new records for iran fauna. the results of determining the egg masses' densities on different rice varieties (including, tarom, fajr, khazar, shafagh, tabesh, sahel, neda, pouya, and kadus) indicated that the highest egg density was obtained on the varieties tarom, fajr, and khazar and the lowest one on tabesh. also, the egg masses' density was significantly different in different locations of mazandaran (including, savadkooh, babolsar, mahmood-abad, babol, fereydon-kenar, sari, nour, amol); the highest population density was observed in sari and amol and the lowest density in nour. the results of population fluctuations of spiders in paddy fields indicated that the population density was increased through the crop season (april-august), but insecticides’ application decreases the density severely. also the population dynamics of spiders was significantly different during the days, and the highest density was obtained in 10 a.m. and 18 p.m. and the lowest was 12 because of warmer weather condition.