The contribution of beetle banks to farmland biodiversity

Create beetle banks

A replicated, paired, site comparison study in 1999 on five farms in the UK (Thomas et al. 2000) found that beetle banks had a similar abundance of butterfly and moth caterpillars to field margins, but that the abundance and species richness of adult butterflies was lower on beetle banks than in hedgerows. The abundance of butterfly and moth caterpillars did not differ significantly between beetle banks (0.4 individuals/sweep) and field margins (0.5 individuals/sweep). However, both the abundance (1–2 individuals/transect) and species richness (0.5–2 species/transect) of adult butterflies were lower in beetle banks than along hedgerows (abundance: 2–6 individuals/transect; richness: 1–3 species/transect). A total of 12 species from three families were recorded on beetle banks, compared to 19 species from four families along hedgerows. In summer 1999, butterfly and moth caterpillars were sampled by sweep-netting on 22 beetle banks of different ages and 22 permanently established field margins across five farms. Adult butterflies were recorded on 82 transects along beetle banks and hedgerows in June, July and August 1999.

(Summarised by: Andrew Bladon, edited from Farmland synopsis)

Plant new hedges

A replicated, paired, site comparison study in 1999 on five farms in the UK (Thomas et al. 2000) found that the abundance and species richness of butterflies was higher along hedgerows than on beetle banks established in the centre of fields. Along hedgerows both the abundance (2–6 individuals/transect) and species richness (1–3 species/transect) of adult butterflies were higher than on beetle banks (abundance: 1–2 individuals/transect; richness: 0.5–2 species/transect). A total of 19 species from four families were recorded along hedgerows, compared to 12 species from three families on beetle banks. Adult butterflies were recorded on 82 transects along hedgerows and beetle banks on five farms in June, July and August 1999.

(Summarised by: Andrew Bladon, edited from Farmland synopsis)

Plant grass buffer strips/margins around arable or pasture fields

A replicated, paired, site comparison study in 1999 on five farms in the UK (Thomas et al. 2000) found that grass field margins had a similar abundance of butterfly and moth caterpillars to beetle banks established in the centre of fields. The abundance of butterfly and moth caterpillars did not differ significantly between field margins (0.5 individuals/sweep) and beetle banks (0.4 individuals/sweep). In summer 1999, butterfly and moth caterpillars were sampled by sweep-netting on 22 permanently established grass field margins and 22 beetle banks of different ages across five farms.

(Summarised by: Andrew Bladon, edited from Farmland synopsis)

Create beetle banks

A replicated, paired, controlled study in the two winters of 1997-1999 and summer 1999 on five farm estates in the UK (Thomas et al. 2000) found different patterns of density and diversity for ground beetles (Carabidae), rove beetles (Staphylinidae) and spiders (Araneae) between five pairs of beetle banks and field margins in two consecutive winters. Rove beetle diversity was lower in beetle banks than in field margins in both winters, but density in beetle banks increased significantly between winters. There were no significant effects on ground beetles. The overall catch of chick-food invertebrates was lower in 22 beetle banks than in paired field margins on five farm estates, but the abundance of key prey groups was similar. There was no difference in grasshopper and bushcricket (Orthoptera) species richness between the two habitats (on average 1.4 species in beetle banks, 1.8 in field margins), but older beetle banks held higher abundances of grasshoppers and bushcrickets. Both abundance and species richness of butterflies and moths (Lepidoptera) was significantly lower in beetle banks than in field margins in June, July and August, but both habitats peaked in July. Destructive turf samples were collected randomly from the two habitats to assess predatory invertebrates. Chick-food invertebrates and grasshoppers and bushcrickets were sampled through sweep-netting and butterflies and moths through standard transect walks. This study was part of the same experimental set-up as (Thomas 2001, Thomas et al. 2001, Thomas 2002, Thomas et al. 2002).

Create beetle banks

A paired, replicated, controlled study in winters 1997-1998 and 1998-1999 and summer 1999 on five farms in the UK (Thomas et al. 2000) found fewer rove beetles (Staphylinidae) on beetle banks (approximately 320-480 individuals/m²) than in field margins (560-680 individuals) in both winters, however ground beetle (Carabidae) and spider (Araneae) numbers were similar between beetle banks (200-240 ground beetles/m² and 360-440 spiders/m²) and field margins (200-280 ground beetles/m² and 400-500 spiders/m²). Ground beetle and spider diversity was slightly higher in beetle banks than field margins and rove beetle diversity was higher in field margins. Of the other invertebrates sampled (not specifically listed as natural enemies or pests), soldier beetles (Cantharidae), typical bugs (Heteroptera), other Auchenorrhyncha (excluding leafhoppers (Cicadellidae), planthoppers (Delphacidae) and bugs (Hemiptera)), other spiders, small flies (Diptera) and ants (Formicidae) were significantly more abundant on field margins than beetle banks. Total invertebrate abundance was also higher on field margins than beetle banks (averaging 64.7 vs. 46.7 invertebrates/sweep net). Predatory invertebrates were sampled on five beetle banks in winter 1997-1998 and 1998-1999. Other invertebrates were sampled on 22 beetle banks on five farms in summer 1999. Banks were paired with a neighbouring field margin. This study was part of the same experimental set-up as Thomas 2001 and Thomas 2002.