Abundance and species richness of field‐margin and pasture spiders (Araneae) in Canterbury, New Zealand

Abstract

The density and species composition of ground-dwelling spiders were assessed using suction sampling from August 1994 to July 1995 at various distances from a field edge into a single grazed pasture, and from March 1996 to March 1997 in the same and three additional grazed pastures and adjacent fenced shelterbelts on the Canterbury Plains, New Zealand. Spider density declined rapidly with distance from the shelterbelt (mean 241 m -2 ) into the pasture (means 72.5 m -2 at 2.5 m, and 10.3 m -2 at 5 m). Mean spider densities in the four pastures were 53.0 m -2 while in the shelterbelts they reached 316 m -2 . The fauna in both habitats was dominated by the European linyphiid, Tenuiphantes tenuis (Blackwall). An unidentified theridiid was common only in the shelterbelt, while unidentified immature linyphiids and theridiids were common in both habitats. Of the c. 28 species collected, 25 were found in shelterbelts, and 13 in pasture. Thirteen endemic, one native, and one introduced species were found only in shelterbelts, while from pasture all but two endemic species were also recognised from shelterbelts. There was little evidence that the shelterbelts acted as refuges for spiders which could subsequently disperse to the adjacent paddocks.

Spiders (Araneae) and harvestmen (Opiliones) in arable crops and grasses in Canterbury, New Zealand

“…Topping & Lövei (1997) also recorded higher species richness in pasture (16 species) as compared with wheat (two species). Similar species richness and composition to those found in the present study were reported in North Island and Canterbury pasture (Topping & Lövei 1997;McLachlan & Wratten 2003). The most common species sampled in the present study was T. tenuis, which was probably introduced from Europe (Millidge 1988).…”

“…2-5). McLachlan & Wratten (2003) recorded a mean population density of 53.0 spiders per square metre throughout the year for all Canterbury pastures sampled with a minimum of 6.8 m-2 and a maximum of 77 m-2 , which fall within the range found in the present study.…”

“…Topping & Lövei (1997) recorded high numbers of an unidentified lycosid species, likely to be A. hilaris, in North Island pasture. This spider was one of the more numerous species in pasture in Nelson (Martin 1983) and Canterbury (McLachlan & Wratten 2003). Anoteropsis hilaris has also been reported in high numbers in carrot fields (Sivasubramaniam et al 1997) and bean crops (Hodge & Vink 2000).…”

“…The most common species sampled in the present study was T. tenuis, which was probably introduced from Europe (Millidge 1988). This species was also reported as the most abundant spider species in North Island pasture (Topping & Lövei 1997) and Canterbury pasture (McLachlan & Wratten 2003). Tenuiphantes tenuis is also common in agroecosystems in England and other European countries (Sunderland et al 1986;Topping & Sunderland 1994b;Sunderland 1996;Topping & Lövei 1997).…”

“…The shortage of publications on spiders in New Zealand agroecosystems is surprising given that New Zealand has a large and diverse spider fauna estimated to include over 2500 species (Forster & Forster 1999) and more than 13.9 million hectares (52%) of New Zealand is farmland (Statistics New Zealand 2002). To date there have been only three research publications dealing specifically with spiders in New Zealand agroecosystems: Topping & Lövei (1997) investigated spider density and diversity in relation to disturbance in pasture and wheat agroecosystems in the lower North Island; Hodge & Vink (2000) assessed the spiders and harvestmen in Canterbury bean crops; and McLachlan & Wratten (2003) compared spider density and species composition between field margins and pasture in Canterbury. A few other papers have been published on predatory arthropods, including spiders and harvestmen, in New Zealand agroecosystems (e.g., Berry et al 1996;Sivasubramaniam et al 1997).…”