Remove, control or exclude invertebrate herbivores
Overall effectiveness category Evidence not assessed
Number of studies: 1
Background information and definitions
Outbreaks of invertebrate herbivores can cause problems for other species, including butterflies and moths, through the competition for food, induced food plant resistance, increased food plant mortality, or increases in predator, parasitoid or pathogen abundance (Scriber 2004). This intervention includes studies investigating the impact of attempting to exclude, remove, or control the density of invertebrate herbivores to allow vegetation to recover, for the benefit of butterfly or moth populations.
For studies on the control of vertebrate herbivores, see “Remove, control or exclude vertebrate herbivores”.
Scriber J.M. (2004) Non-target impacts of forest defoliator management options: Decision for no spraying may have worse impacts on non-target Lepidoptera than Bacillus thuringiensis insecticides. Journal of Insect Conservation, 8, 241–261.
Supporting evidence from individual studies
A replicated, site comparison study in 1995–1998 in 28 woodland sites in Argyll, UK (Feber et al 2011) found that at sites fenced to exclude grazing animals there was a higher density of pearl-bordered fritillary butterflies Boloria Euphrosyne than at unfenced sites. In sites within woodland that were fenced to exclude deer there was a higher density of pearl-bordered fritillaries (6.8 butterflies/hectare) than at sites where deer were not excluded (3.7 butterflies/ha). In woodland edge sites where fencing excluded deer, there was a higher density of pearl-bordered fritillaries (10.7 butterflies/ha) than where deer were not excluded and sheep were grazing (0.1 butterflies/ha). In May and June 1998 mark-release-recapture surveys of pearl-bordered fritillaries were conducted at the 28 sites of woodland and woodland edge in Lochawe. Within this area were two woods designated in 1995–1996 under the Woodland Grant Scheme and fenced to exclude deer (6 sampling sites in woodland, 12 at woodland edge). These were compared to other woodland sites without deer fencing (3 sites) and woodland edge sites without fencing which were also sheep grazed (7 sites).Study and other actions tested