CHAPTER 1
Introduction
1.1 The purpose of Conservation Evidence synopses
This book, Bee Conservation, is the first in a series of synopses that will cover different species groups and habitats, gradually building into a comprehensive summary of evidence on the effects of conservation interventions for all biodiversity throughout the world.
By making evidence accessible in this way, we hope to enable a change in the practice of conservation, so it can become more evidence-based. We also aim to highlight where there are gaps in knowledge.
1.2 Who this synopsis is for
If you are reading this, we hope you are someone who has to make decisions about how best to support or conserve biodiversity. You might be a land manager, a conservationist in the public or private sector, a farmer, a campaigner, an advisor or consultant, a policymaker, a researcher or someone taking action to protect your own local wildlife. Our synopses summarise scientific evidence relevant to your conservation objectives and the actions you could take to achieve them.
We do not aim to make your decisions for you, but to support your decision-making by telling you what evidence there is (or isn't) about the effects that your planned actions could have.
When decisions have to be made with particularly important consequences, we recommend carrying out a systematic review, as the latter is likely to be more comprehensive than the summary of evidence presented here. Guidance on how to carry out systematic reviews can be found from the Centre for Evidence-Based Conservation at the University of Wales, Bangor (www.cebc.bangor.ac.uk).
1.3 The Conservation Evidence project
The Conservation Evidence project has three parts:
1. An online, open access journalConservation Evidence publishes new pieces of research on the effects of conservation management interventions. All our papers are written by, or in conjunction with, those who carried out the conservation work and include some monitoring of its effects.
2. An ever-expanding database of summaries of previously published scientific papers, reports, reviews or systematic reviews that document the effects of interventions.
3. Synopses of the evidence captured in parts one and two on particular species groups or habitats. Synopses bring together the evidence for each possible intervention. They are freely available online and available to purchase in printed book form.
These resources currently comprise over 2,000 pieces of evidence, all available in a searchable database on the websitewww.conservationevidence.com.
Alongside this project, the Centre for Evidence-Based Conservation (www.cebc.bangor.ac.uk) and the Collaboration for Environmental Evidence (www.environmentalevidence.org) carry out and compile systematic reviews of evidence on the effectiveness of particular conservation interventions. These systematic reviews are included on the Conservation Evidence database.
Of the 59 bee conservation interventions identified in this synopsis, one is the subject of a current systematic review (Systematic Review number 72: Does delaying the first mowing date increase biodiversity in European farmland meadows? www.environmentalevidence.org/SR72.html). We identify an immediate need for a systematic review in relation to one other set of interventions (agri-environment schemes), and a potential need for systematic reviews for three further interventions, should they become more widely practised (nest boxes for solitary bees and captive rearing of bumblebees or solitary bees).
1.4 Scope of the Bee Conservation synopsis
This synopsis covers evidence for the effects of conservation interventions for native, wild bees.
It is restricted to evidence captured on the websitewww.conservationevidence.com. It includes papers published in the journal Conservation Evidence, evidence summarised on our database and systematic reviews collated by the Collaboration for Environmental Evidence.
It does not include evidence from the substantial literature on husbandry methods for the largely domesticated honey bee Apis mellifera. It does include husbandry methods where they are relevant to native, wild bee species that are declining or threatened, such as bumblebees (Bombus spp.) and stingless bees (Meliponinae). Although the number of managed honey bee colonies is known to have declined in Europe and America, it is seldom the native subspecies that is kept and so we consider this to be outside the remit of Conservation Evidence. We do include some interventions and evidence relating to the conservation of subspecies of Apis mellifera in areas where they are native.
Evidence from all around the world is included. If there appears to be a bias towards evidence from northern European or North American temperate environments, this reflects a current bias in the published research that is available to us.
1.5 How we decided which bee conservation interventions to include
Our list of interventions has been agreed in partnership with an Advisory Board made up of international conservationists and academics with expertise in bee conservation. Although the list of interventions may not be exhaustive, we have tried to include all actions that have been carried out or advised to support populations or communities of wild bees.
1.6 How we reviewed the literature
In addition to evidence already captured by the Conservation Evidence project, we have searched the following sources for evidence relating to bee conservation: four specialist bee or insect conservation journals, from their first publication date to the end of 2009 (Apidologie, Journal of Apicultural Research, Insect Conservation and Diversity, Journal of Insect Conservation); ISI Web of Knowledge searched for papers with 'bee' as a search term, from 1997 to 2009 inclusive; all reports concerning bees published by Natural England or the UK Bumblebee Working Group up to 2009; other relevant papers or books frequently cited within the bee conservation literature, going back to 1912.
In total, 168 individual studies are covered in this synopsis, all included in full or in summary on the Conservation Evidence website.
The criteria for inclusion of studies in the Conservation Evidence database are as follows:
• There must have been an intervention that conservationists would do
• Its effects must have been monitored quantitatively
In some cases, where a body of literature has strong implications for conservation of a particular species group or habitat, although it does not directly test interventions for their effects, we refer the reader to this literature. For example, the proportion of natural habitat in farmland has often been shown to affect bee diversity, but no studies have yet intervened by restoring natural or semi-natural habitat and monitoring the effect on bees in surrounding farmland. In cases such as these, we briefly refer to the relevant literature, but present no evidence.
1.7 How the evidence is summarised
Conservation interventions are grouped primarily according to the relevant direct threats, as defined in the International Union for the Conservation of Nature (IUCN)'s Unified Classification of Direct Threats (www.iucnredlist.org/technicaldocuments/classification-schemes). In most cases, it is clear which main threat a particular intervention is meant to alleviate or counteract. Interventions to help bees threatened by agricultural land use change are very different from those intended to avoid the adverse effects of invasive species, for example.
Not all IUCN threat types are included, only those that threaten bees, and for which realistic conservation interventions have been suggested.
We have separated out three important categories of conservation action, as defined by the IUCN, which are relevant to a variety of situations, habitats and threats. They are: Chapter 10 Providing artificial nest sites, Chapter 11 Captive breeding and rearing of wild bees and Chapter 12 Education and awareness-raising. These respectively match the following categories of conservation actions defined by the IUCN: 'species management: species recovery', 'species management: ex situ conservation' and 'education and awareness'.
Normally, no intervention or piece of evidence is listed in more than one place, and when there is ambiguity about where a particular intervention should fall there is clear cross-referencing. The only exception to this is in Chapter 4.1 Introduce agri-environment schemes that reduce spraying. Due to the prevalence of review papers in this section, some individual studies are referred to that are also referred to in more specific sections on particular agri-environment prescriptions.
In the text of each section, studies are presented in chronological order, so the most recent evidence is presented at the end. The summary text at the start of each section groups studies according to their findings.
At the start of each chapter, a series of key messages provides a rapid overview of the evidence. These messages are condensed from the summary text for each intervention.
In general, we do not update taxonomy, but employ species names used in the original paper. However, in some cases it is sensible to replace the names with their modern equivalent. For example, papers from the early 20th century may describe bumblebees in the genus Bremus not Bombus. This would be changed and Bremus included as a keyword in the database of summaries. Any replacement names are those used in the ITIS (Interagency Taxonomic Information System) World Bee Checklist (www.itis.gov/beechecklist.html). Where possible, common names and Latin names are both given the first time each species is mentioned within each intervention.
Background information is provided where we feel recent knowledge is required to interpret the evidence. This is presented separately and relevant references included in the reference list at the end of each intervention section.
References containing evidence of the effects of interventions are marked with a weblink icon (www ). In electronic versions of the synopsis, they are hyperlinked directly to the Conservation Evidence summary. If you do not have access to the electronic version of the synopsis, typing the first author's name into the 'Quick Search' facility onwww.conservationevidence. com is the quickest way to locate summaries.
The information in this synopsis is available in three ways:
As a book, published by Pelagic Publishing and for sale from: www.pelagicpublishing.com
As a.pdf file to download from: www.conservationevidence.com
As text for individual interventions on the searchable database at: www.conservationevidence.com"
1.8 Terminology used to describe evidence
Unlike systematic reviews of particular conservation questions, we do not quantitatively assess the evidence, or weight it according to quality. However, to allow you to interpret evidence, we make the size and design of each trial we report clear. The table below defines the terms that we have used to do this.
The strongest evidence comes from randomised, replicated, controlled trials with paired sites and before and after monitoring.
1.9 How you can help to change conservation practice
If you know of evidence relating to bee conservation that is not included in this synopsis, we invite you to contact us, via thewww.conservationevidence.com website.
Following guidelines provided on the site, you can submit a summary of a previously published study, or submit a paper describing new evidence to the Conservation Evidence journal. We particularly welcome summaries written by the authors of papers published elsewhere, and papers submitted by conservation practitioners.
CHAPTER 2
Threat: residential and commercial development
Key Messages
Plant parks and gardens with appropriate flowers
Three North American trials have found more wild bees in gardens planted with bee forage plants, either relative to conventionally managed gardens or following planting.
Practise 'wildlife gardening'
A UK site comparison study found more species of bumblebee in domestic city gardens with lower intensity of management, a measure reflecting tidiness of the garden and use of pesticides.
Protect brownfield sites
We have captured no evidence for the effects of interventions to protect brownfield sites from insensitive re-development.
Conserve old buildings or structures as nesting sites for bees
We have captured no evidence for the effects of conserving old buildings and structures suitable for nesting, or containing nesting wild bees.
For all evidence relating to the use of nest boxes, see Chapter 10 Providing artificial nest sites for bees.
• Two replicated trials in the USA and Canada have found more wild bees (either more species or more individuals) in gardens planted with bee forage or native plants, relative to conventionally managed gardens. Another USA trial found more bee species after the addition of bee forage plants to a community garden. Three trials in the UK or USA have shown that native flowering plants or bee forage plants are well used by wild bees when planted in gardens. A UK trial demonstrated that some popular non-native or horticulturally modified garden flowers are not frequently visited by insects, despite providing nectar in some cases.
Natural shaped, rather than horticulturally modified varieties of garden plants are recommended for foraging insects. A trial of nearly natural and horticulturally modified varieties of six popular garden plants in the Cambridge University Botanic Gardens, Cambridgeshire, UK (Comba et al. 1999a) found that bumblebee visits to hollyhock Alcea rosea and larkspur Consolida sp. were more frequent on natural, single-petalled forms than on horticulturally modified, double-petalled varieties. Bee visits to four of the flower types – nasturtium Tropaeolum majus, pansy Viola x wittrockiana, marigold Tagetes patula and snapdragon Antirrhinum majus – were infrequent despite ample nectar provision from some varieties. There was a tendency for wild bees to prefer natural flower shapes in pansy, marigold and snapdragon, but not in nasturtium.
A trial of 25 native flowering herb species planted in the Cambridge University Botanic Gardens, UK, identified 16 species frequently visited by wild bees (Comba et al. 1999b). Ten species (seven of which were frequently visited by wild bees) were shown to provide abundant nectar in the garden environment.
A trial of six native plant species (marsh woundwort Stachys palustris, wood betony S. officinalis, purple loosestrife Lythrum salicaria, common toadflax Linaria vulgaris, bird's-foot trefoil Lotus corniculatus and meadow clary Salvia pratensis) recommended for pollinator-friendly gardens in the Cambridge University Botanic Gardens, UK, found all six were nectar-rich and frequently visited by wild bees (Corbet et al. 2001). A double-flowered variant of bird's-foot trefoil tested in the same study produced no nectar and attracted no insects.
A replicated trial in the Phoenix metropolitan area, in the Sonoran Desert of the USA, found that eight gardens planted with dry-loving plants (xeric landscaping) supported a greater diversity of bees than eight gardens planted with non-native plants such as grasses that needed to be irrigated (McIntyre & Hostetler 2001). In September, xeric gardens had approximately 10 bee species, compared to less than five species/garden in ordinary gardens.
Tommasi et al. (2004) measured bee abundance and diversity in wild areas, and gardens managed for wildlife or managed traditionally, in Vancouver, British Columbia, Canada (five to eight sites of each type). They found that gardens managed for wildlife under the 'Naturescape' programme, sown with native plant species and infrequently mown grass areas, had significantly more bee individuals than traditionally managed gardens with mown lawns and non-native plants such as petunia Petunia sp., tulip Tulipa sp., pansy Viola sp. and rhododendron Rhododendron sp. (approximately 45 wild bee (non-Apis mellifera) individuals caught/hour of sampling on average in Naturescape gardens, compared to less than 20 bees/hour in traditional gardens). Naturescape gardens did not have significantly more bee species than traditional gardens.
