Manipulating the abundance of Lepthyphantes tenuis (Araneae: Linyphiidae) by field margin management

Published source details Bell J.R., Johnson P.J., Hambler C., Haughton A.J., Smith H., Feber R.E., Tattersall F.H., Hart B.H., Manley W. & Macdonald D.W. (2002) Manipulating the abundance of Lepthyphantes tenuis (Araneae: Linyphiidae) by field margin management. Agriculture, Ecosystems & Environment, 93, 295-304.
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This study is summarised as evidence for the following.

	Action	Category
	Delay mowing or first grazing date on pasture or grassland Action Link
	Create uncultivated margins around intensive arable or pasture fields Action Link
	Plant nectar flower mixture/wildflower strips Action Link

Delay mowing or first grazing date on pasture or grassland

A replicated, randomised, controlled study from 1987 to 1996 in Oxfordshire, UK (Bell et al. 2002) found that the predatory sheet web spider Lepthyphantes tenuis was approximately 2.5 and 6.5 times less abundant in cut versus uncut (control) field margins in May and July respectively. Following an early (April) cut, spider numbers in cut field margins recovered to match numbers in uncut control margins by July (around 4 spiders/m² in each). Recovery was less successful following a later (June) cut, with around 10 spiders/m² in cut field margins compared with around 15 spiders/m² in uncut control margins by September. Field margin treatment plots measured 2 x 50 m and were replicated around six arable fields. Spiders were counted in suction trap (D-vac) samples with data pooled from 1990, 1991, 1995 and 1996.
Create uncultivated margins around intensive arable or pasture fields

A randomized, replicated trial from 1987 to 1996 in Oxfordshire, UK (Bell et al. 2002), found greater numbers of predatory sheet web spiders Lepthyphantes tenuis on field margins left uncut and unsprayed with herbicide. In September, when most of the spiders were caught, there were significantly fewer L. tenuis spiders in margins (sown and unsown) that were cut in June (around 10 spiders/m², compared to >15 spiders/m²in plots cut in spring and autumn, or not cut). In May and July, plots with a recent cut (April or June-cut treatments respectively) also had lower numbers of L. tenuis than other plots. Spraying unsown plots with herbicide reduced the numbers of L. tenuis later in the same year (average 4 and 10 spiders/m² in sprayed plots in July and September respectively, compared to 8 and 20 spiders/m² on unsprayed plots in July and September). Plots where the vegetation was cut but not removed did not have more spiders than plots where cut vegetation was removed. L. tenuis individuals were counted in invertebrate samples collected using a suction trap (D-Vac) in May, July and September 1990, 1991, 1995 and 1996. This study was part of the same experimental set-up as Feber et al. 1994, Feber et al. 1996, Baines et al. 1998, Bell et al. 1999, Haughton et al.1999, Smith et al. 2010).
Plant nectar flower mixture/wildflower strips

A randomized, replicated trial from 1987 to 1996 in Oxfordshire, UK (Bell et al. 2002) found no difference in numbers of the predatory sheet web spider Lepthyphantes tenuis between field margins sown with a wildflower mix and naturally regenerated margins. In September, when most of the spiders were caught, there were significantly fewer L. tenuis individuals in margins (sown and unsown) that were cut in June (around 10 individuals/m²) compared to more than 15/m²in plots cut in spring and autumn, or not cut. In May and July, plots with a recent cut (April- or June-cut treatments respectively) also had lower numbers of L. tenuis than other plots. L. tenuis individuals were counted in invertebrate samples collected using a suction trap (D-Vac) in May, July and September 1990, 1991, 1995 and 1996. This was part of the same study design as Feber et al. 1994, Feber et al. 1996, Baines et al. 1998, Bell et al. 1999, Haughton et al. 1999, Smith et al. 1999, Smith et al. 2010.