Action: Provide nest boxes for bees (solitary bees or bumblebees)
- Ten studies (nine replicated trials and a review of studies) from Germany, Poland and the UK of solitary bee nest boxes all showed the nest boxes were readily used by bees. Two replicated studies found the local population size or number of emerging red mason bees increased when nest boxes were provided. One replicated trial in Germany showed that the number of occupied solitary bee nests almost doubled over three years with repeated nest box provision at a given site.
- Two replicated trials tested bumblebee nest boxes and both found very low uptake, 2% or less.
- Occupancy rates of solitary bee nest boxes, where reported (two replicated studies), were between 1 and 26% of available cavities. Five studies (four replicated trials and a review of studies) report the number of bee species found in the nest boxes – between 4.6 and 33 species.
- One replicated study from Germany found nest boxes should be placed 150-600 m from forage resources (Gathmann & Tscharntke 2002). A replicated study from Poland found the highest production of red mason bees per nest was from nesting materials of reed stems or wood.
This intervention involves providing nest boxes for solitary bees or bumblebees. The majority of the studies summarized here tested the effect of providing nest sites on solitary bees. Solitary bee species nest either in cavities such as hollow stems or bored holes in wood or masonry, or in the ground. Many of the studies used solitary bee nest boxes consisting of common reed Phragmites australis stems, other options include wood or paper tubes. The success of nest boxes in providing suitable alternative nesting habitats for bumblebees may depend on a number of factors including nest box design, siting and availability of foraging resources (Lye et al. 2011).
Lye G.C., Park K.J., Holland J.M. & Goulson D. (2011) Assessing the efficacy of artificial domiciles for bumblebees. Journal for Nature Conservation, 19, 154-160.
Supporting evidence from individual studies
A replicated study in 1966-1969 from 20 sites in southern England found (Free & Williams 1970) red mason bees Osmia rufa readily occupied artificial nest boxes comprising metal food cans filled with drinking straws (straw diameter 5-7 mm). In the first year of the trial, 349 cans were recovered, of these 44 (13%) had one or more straws occupied by a red mason bee nest. Over the following two years, there was a tendency by this species to reoccupy cans. Osmia caerulescens and species of Megachile also occupied the cans. In March 1966, 398 cans were distributed across sites in eight counties, 349 cans were recovered in September. In 1967, 1968 and 1969 cans were again placed at several of the sites. Cans were attached to tree branches and fence posts 1-2 m above the ground. The open end of each can faced east or south and was tilted slightly downwards from the horizontal to prevent rain entering.
A trial (unequally replicated) of 654 bumblebee Bombus spp. nest boxes over three years (1989-1991) in farmland, gardens and fenland in Cambridgeshire, UK (Fussell & Corbet 1992) found only 10 boxes were occupied (1.5%). The nest boxes tested were wooden boxes raised 10 cm or 1 m above the ground, or nest sites constructed with bricks and concrete tiles on the ground. Dry moss, felt or shredded textiles were added as bedding. Two common and widespread bumblebee species used boxes of both types: the early bumblebee Bombus pratorum and the common carder bee B. pascuorum.
A replicated, controlled study in May to October 1990 in 40 farmland sites (10 field types, four replicates each) near Karlsruhe, south Germany (Gathmann & Tscharntke 1993) (same study as (Gathmann et al. 1994)) found a significantly higher species richness of solitary bees (Apidae) in artificial reed Phragmites australis stem nests in unsown sites with naturally developed vegetation (approximately 7.9 species) than in sown fields (approximately 4.6 spp.). Unsown sites with naturally developed vegetation included one- and two-year old mown and unmown set-asides and old meadow orchards. Crops on sown fields were peas, barley, rye, clover Trifolium spp.-grass mixture and phacelia Phacelia tanacetifolia. Mowing of set-asides took place in late June-early July. Three artificial nests (each with two 750 ml cans filled with approximately 180 reed stems) were located in each field centre.
A replicated study in April 1990 of 240 bundles of reed Phragmites australis stems in 40 fields of 10 management types, in Kraichgau, southwest Germany (Gathmann et al. 1994) (same study as (Gathmann & Tscharntke 1993)) found of 43,200 available reed stems, 292 were occupied by a total of 14 bee (Apidae) species and nine wasp species (Hymenoptera). Five species of bee considered to be endangered in Germany occupied the reed stem nests: Anthidium lituratum, Heriades crenulatus, Megachile alpicola, Osmia gallarum and Osmia leaiana. The two endangered Osmia species were exclusively found in nests in old meadows (more than 30 years old with several old fruit trees). The other three also nested in stems provided in 2-year-old mown set-aside, and two species (A. lituratum and M. alpicola) used reed stems in a variety of field types, including cereal crops. The proportion of larvae in the nests that died from disease or failed parasitism was 13%; 2% were successfully parasitized. Two-hundred-and-forty bundles of reed stems in tins were put out, six in each of 40 fields of 10 management types, including various types of set-aside, crop fields and old meadows. This study is also referred to by (Tscharntke et al. 1998).
A replicated six-year trial at two experimental farms near Poznan, western Poland (Wójtowski et al. 1995) demonstrated that the red mason bee Osmia rufa readily nests in bundles of reed Phragmites australis stems 7-8 mm in diameter. Bundles of reed stems in roofed containers were set out in March from 1989 to 2004. In winter each year, occupied reed stems were collected and kept in refrigerators over winter. The following spring, overwintered reed stems were placed out in incubators along with new nest boxes. In the first year (1989), 1,750 red mason bee cocoons were introduced with the nest boxes at each site. The behaviour of emerging bees was observed. At one site the total number of emerging red mason bees increased from 1,453 in 1989 to 108,973 in 1994 (a 75-fold increase). At the other site the number of emerging red mason bees increased from 1,519 in 1989 to 13,413 in 1992, after which the population was resettled for other experiments.
A replicated trial from 1994 to 1996 in central Germany (Gathmann & Tscharntke 1997) found that reed Phragmites australis stem nest boxes were occupied by 13 species of bee (Apidae), 19 species of wasp and 17 species of parasite and parasitoid (Hymenoptera). In total, 8,303 nests were made. The number of occupied stems almost doubled over three years from 1,761 in 1994 to 3,326 in 1996. One-hundred-and-fifty reed stem nest boxes (plastic tubes filled with 150 lengths of 20 cm reed stem) were placed at 15 different sites. Three replicates in each of five habitat types were studied: sown field margin strips, set aside fields (sown with clover Trifolium spp.-grass mixture), extensively used grassland, chalk grassland, orchard meadows. Ten reed stem nest boxes were placed in each site. In autumn, nests were dissected and occupants identified. This study is also referred to by (Tscharntke et al. 1998)).
A review of a series of four trials (two (Gathmann et al. 1994, Gathmann & Tscharntke 1997) already described above) between 1990 and 1996 in Germany (Tscharntke et al. 1998) found 33 bee species (Apidae) (not including parasitic bees) used reed Phragmites australis bundles placed in tins or plastic tubes attached to wooden posts across a variety of agricultural and semi-natural habitats including orchard meadows, old hay meadows, set-aside fields, field margins and chalk grasslands. Two studies documented predation and parasitism rates in reed bundles in tins or plastic tubes attached to wooden posts in various semi-natural and agricultural habitats. The average percentage killed by predators or parasites was 21% for bees or 28% for wasps on average.
A replicated trial in 1997 of reed Phragmites australis stem nest boxes at 15 different agricultural sites near Göttingen in Lower Saxony, Germany (Gathmann & Tscharntke 2002) (same study as (Steffan-Dewenter 2002)) found nest boxes had a 50% chance of being occupied by two specialized (oligolectic) species of bee (Apidae) - Chelostoma rapunculi and Megachile lapponica - at a distance of 256-260 m from a patch of their required forage plants. The study also found that female solitary bees of four medium to large European species Andrena barbilabris, A. flavipes, A. vaga and the red mason bee Osmia rufa have a maximum foraging range between 150 to 600 m, so nest boxes have to be placed within this distance of forage resources. There was no colonization of nest boxes by C. rapunculi more than 300 m from a patch of its food plant, bellflowers Campanula spp.. Nest boxes consisted of 150-180 stem sections of common reed, with diameters of 2-10 mm, 15-20 cm-long and put in 10-13 cm diameter plastic tubes or tins. Reed-filled tubes were attached to 1.5 m-long wooden posts above the ground, with four nest boxes to a post. Two posts (eight nest boxes) were placed at 15 different sites from April to October. Patches of bellflower and willowherb Epilobium spp. were recorded in a 1 km radius from the nest boxes at each site. Nesting females (141 individuals) of the four other solitary bee species were marked, then moved in darkened boxes 50 to 2000 m away from their nests. Returning individuals were recorded. This experiment was run on sandy grasslands near Mannheim in 1995, and on chalk grasslands near Göttingen in 1997, between 10:00 h and 18:00 h on sunny days during the main flight period for each bee species.
A replicated trial in 1997 of 120 reed Phragmites australis stem nest boxes at 15 different agricultural sites near Göttingen in Lower Saxony, Germany (Steffan-Dewenter 2002) (same study as (Gathmann & Tscharntke 2002)) found the boxes were occupied by 11 species of bee (Apidae). The red mason bee Osmia rufa and the common yellow face bee Hylaeus communis were the most widespread and common nest box occupants in this study. Fourteen percent of bee brood cells were attacked by natural enemies (brood parasites, parasitoids or predators). Nest boxes consisted of 150-180 stem sections of common reed, with diameters of 2-10 mm, cut 20 cm-long and put in 10.5 cm diameter plastic tubes. Reed-filled tubes were attached to wooden posts 1-1.2 m above the ground, with four nest boxes to a post. Two posts (eight nest boxes) were placed at 15 different sites from April to October. In October, occupied reeds were cut open and the number of brood cells in each stem counted. Occupants were reared in the laboratory and identified to species where possible.
A replicated study from 1998 to 1999 in 45 orchard meadows in central Germany (Steffan-Dewenter & Leschke 2003) recorded 17,278 cells from 13 species of solitary bee (Apidae) using 540 reed stem nest boxes. Orchards were either mown once or twice a year, grazed (usually by sheep) or had no management for at least 5 years. In each orchard, three wooden posts (1.5 m height, 5-7 cm diameter), each with four 'nesting traps' (total of 540 traps), were set up at regular distances from April to September in 1998 and 1999. The traps comprised 150-180, 20 cm-long common reed Phragmites australis stem sections, packed into 10.5 cm diameter plastic tubes. Traps were collected at the end of September and bees and wasps identified to genus, or species, where possible, as were parasitoids and parasites of stored food.
A replicated study in 2000 and 2001 at an agricultural experimental station in Poznan County, Poland (Wilkaniec & Gieidasz 2003) tested six different nesting materials for the red mason bee Osmia rufa and found all materials were used by female bees, but the highest production of bees per nest was from reed Phragmites australis stems (3.5 bees/nest in 1999) or wood (7.2 bees/nest in 2000). Nests in paper tubes were all parasitized. Nests in plastic were well occupied (80-100%) but had a low success rate (0.2-1.8 bees/nest), partly due to mould. For each trial, 150 nests of each of the following materials were tested: reed stems, plastic tubes, paper tubes (bundles), wood, cork (grooved boards joined together in blocks), and holes drilled into wood, lined with printer acetate.
A replicated study in 1998 of 12 trap nests in each of five orchard meadows near Göttingen, Germany (Steffan-Dewenter & Schiele 2004) found trap nests (bundles of common reed Phragmites australis stems) were used as nest sites by the red mason bee Osmia rufa. Three years later, in autumn 2001, a total of 974 newly developed females were counted in 60 such nests and 222 of them were observed re-stocking nests. Bundles of common reed stems (approximately 153 stems, cut 15-20 cm-long) in 10-13 cm diameter plastic tubes, attached to 1.5 m-long wooden posts in groups of four were placed in five orchard meadows. In autumn 2001, all female adults inside the nests were marked with a plastic bee marker. The stems were closed again and stored until spring 2002, when they were placed in emergence boxes on the posts they came from. Trap nests were observed for two or three 30-60 minute periods from 16 to 22 May 2002.
A replicated study of 30 orchard meadows in Lower Saxony, Germany (Steffan-Dewenter & Schiele 2008) found that increasing nest site availability resulted in an increase of red mason bee Osmia rufa local population size from 80 to 2,740 brood cells/site from 1998 to 2002. Each trap nest contained an average of four red mason bee brood cells in common reed Phragmites australis stems. The mean proportion of suitable stems used by the red mason bee increased from 1% in 1998 to 26% in 2002 (highest 96%). The proportion of orchard meadows occupied by the red mason bee also increased, from 84% in 1998 to 100% in 2001 and 2002. Following removal of all brood cells in 2003, figures returned to those of 1998. Habitat connectivity did not affect the number of red mason bee brood cells/site. Population size and rates of parasitism (1992: 93%, 2002: 100% of populations) significantly affected population growth rates. The proportion of brood cells of other bee and wasp (Hymenoptera) species in traps decreased with increasing red mason bee occupancy. At each site, 12 trap nests (of 153 common reed segments) were installed each year. Nests were collected in September and then returned to the same posts in the spring (along with new traps).
A replicated trial in 2008 (Lye 2009) of 150 underground bumblebee Bombus spp. nest boxes on Scottish farmland found very low uptake rates. Just 2% of 150 were used. The boxes were made with two pairs of flower pots placed mouth to mouth, buried in the ground. Fifteen underground boxes were placed on each of 10 farms in March and April.
- Free J.B. & Williams I.H. (1970) Preliminary investigations on the occupation of artificial nests by Osmia rufa L. (Hymenoptera, Megachilidae). Journal of Applied Ecology, 73, 559-566
- Fussell M. & Corbet S. (1992) The nesting places of some British bumblebees. Journal of Apicultural Research, 31, 32-41
- Gathmann A. & Tscharntke T. (1993) Bees and wasps in trap nests on sown crop fields and self-sown fallow fields (Hymenoptera Aculeata). Verhandlungen Gesellschaft fur Okologie, 22, 53-56
- Gathmann A., Greiler H.J. & Tscharntke T. (1994) Trap-nesting bees and wasps colonizing set-aside fields: succession and body size, management by cutting and sowing. Oecologia, 98, 8-14
- Wojtowski F., Wilkaniec Z. & Szymas B. (1995) Increasing the total number of Osmia rufa (L.) (Megachilidae) in selected biotopes by controlled introduction method. Pages 177 in: J. Banaszak (ed.) Changes in the fauna of wild bees in Europe. Pedagogical University,
- Gathmann A. & Tscharnkte T. (1997) Bienen und Wespen in der Agrarlandschaft (Hymenoptera Aculeata): Ansiedlung und Vermehrung in Nisthilfen (Bees and wasps in the agricultural landscape (Hymenoptera Aculeata): colonization and augmentation in trap nests). Mitteilungen der Deutschen Gesellschaft für allgemeine und angewandte Entomologie, 91-94
- Tscharntke T., , & Steffan-Dewenter I. (1998) Bioindication using trap-nesting bees and wasps and their natural enemies: community structure and interactions. Journal of Applied Ecology, 35, 708-719
- Gathmann A. & Tscharntke T. (2002) Foraging ranges of solitary bees. Journal of Animal Ecology, 71, 757-764
- Steffan-Dewenter I. (2002) Landscape context affects trap-nesting bees, wasps, and their natural enemies. Ecological Entomology, 27, 631-637
- Steffan-Dewenter I. & Leschke K. (2003) Effects of habitat management on vegetation and above-ground nesting bees and wasps of orchard meadows in Central Europe. Biodiversity and Conservation, 12, 1953-1968
- Wilkaniec Z. & Giejdasz K. (2003) Suitability of nesting substrates for the cavity-nesting bee Osmia rufa. Journal of Apicultural Research, 42, 29-31
- Steffan-Dewenter I. & Schiele S. (2004) Nest site fidelity, body weight and population size of the red mason bee, Osmia rufa (Hymenoptera: Megachilidae), evaluated by mark-recapture experiments. Entomologia Generalis, 27, 123-131
- Steffan-Dewenter I. & Schiele S. (2008) Do resources or natural enemies drive bee population dynamics in fragmented habitats? Ecology, 89, 1375-1387
- Lye G. (2009) Nesting ecology, management and population genetics of bumblebees: an integrated approach to the conservation of an endangered pollinator taxon. PhD thesis, Stirling University.