Collected Evidence: Collected Evidence: Translocate bumblebee colonies in nest boxesWe have captured three small trials in the 1950s and early 1960s testing the effect of translocating bumblebee colonies in nest boxes. Two trials in Canada provided evidence of queen death and one of these showed lower colony productivity following translocation. Just one, a UK trial, concluded that early bumblebee Bombus pratorum colonies adapt well to being moved.  Collected, 20 May 2010 01:34:59 +0100Collected Evidence: Collected Evidence: Restore heathlandOne small trial of early-stage lowland heath restoration activity did not have an adverse effect on bumblebee diversity at one site in southeast England. Two replicated trials in Dorset indicated that long-term restoration of dry lowland heath can restore a bee community similar to that on ancient heaths. One of these studies showed that the community of conopid flies parasitizing bumblebees remained impoverished 15 years after heathland restoration began. We found no evidence on interventions to conserve bees on upland heath or moorland.  Collected, 20 May 2010 03:20:44 +0100Collected Evidence: Collected Evidence: Restore species-rich grassland vegetationOne replicated controlled trial in Scotland showed that species-rich grassland managed under agri-environment schemes attracted more nest-searching queen bumblebees but fewer foraging queens in the spring than unmanaged grassland. Three small trials, two in the UK and one in Germany, found that restored species-rich grasslands had similar flower-visiting insect communities (dominated by bees and/or flies) to paired ancient species-rich grasslands.  Collected, 20 May 2010 07:08:34 +0100Collected Evidence: Collected Evidence: Sow uncropped arable field margins with a native wild flower seed mixFive replicated trials in the UK showed that uncropped field margins sown with wild flowers and subsequently mown support a higher abundance (and in three trials higher species richness) of foraging bumblebees than cropped field edges (all five trials), grassy margins (four trials) or naturally regenerated uncropped margins (three trials). One small trial recorded the same number of bee species on wildflower sown and naturally regenerated strips. Two trials demonstrated that perennial leguminous herbs in the seed mixtures are important forage sources for bumblebees, particularly for long-tongued species. One small replicated trial showed that common long-tongued bumblebee species (Bombus pascuorum and B. hortorum) strongly preferred plots of perennial wildflower seed mix over a mix of annual forage plants. We have captured no evidence on the effects of field margin management on solitary bees.  Collected, 20 May 2010 07:11:24 +0100Collected Evidence: Collected Evidence: Translocate solitary beesOne replicated trial in India showed that translocating carpenter bees Xylocopa fenestrata in immature stages can establish a population at a new site, but if adult bees are translocated a very small proportion remain at the new site.  Collected, 20 May 2010 11:18:56 +0100Collected Evidence: Collected Evidence: Retain dead wood in forest managementWe have found no evidence on the impact of retaining dead wood in forests or woodlands on wild bee communities or populations.  'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected, 20 May 2010 12:43:18 +0100Collected Evidence: Collected Evidence: Restrict certain pesticidesOne site comparison study in Italy showed that a reduction in the number of solitary bee species in late summer associated with repeated applications of the insecticide fenitrothion can be avoided by not applying the insecticide.  Collected, 20 May 2010 17:07:09 +0100Collected Evidence: Collected Evidence: Restore species-rich grassland on road vergesOne replicated controlled trial showed that road verges planted with native prairie vegetation in Kansas, USA supported a greater number and diversity of bees than frequently mown grassed verges.  Collected, 20 May 2010 18:38:51 +0100Collected Evidence: Collected Evidence: Sow uncropped arable field margins with an agricultural nectar and pollen mixFive replicated trials in Europe (three controlled) have documented bumblebees foraging on field margins sown with an agricultural nectar and pollen seed mix. Four replicated trials showed that field margins sown with perennial leguminous flowering plants attract significantly more foraging bumblebees than naturally regenerated (two trials), grassy (four trials) or cropped (three trials) field margins. Three replicated trials showed that a mix of agricultural forage plants including legumes (all annual plants in one trial) attracts greater numbers of bumblebees than a perennial wildflower mix, at least in the first year. Three trials in the UK found evidence that margins sown with agricultural legume plants degrade in their value to bumblebees and would need to be re-sown every few years. We have captured no evidence on the effects of field margin management on solitary bees.  Collected, 20 May 2010 20:59:45 +0100
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What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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