Mason bees

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Horned mason bee ( Osmia cornuta )

As mason bees bees of the closely related genera Osmia and Hoplitis called (not to be confused with mortar bees ). There are also other German names for the species of the genus Hoplitis (stem bees , rock bees , adder bees ). Some types of osmia are also called snail-shell bees. They are solitary bees living individually ; they belong to the Megachilidae family within the bees . The mason bees are closely related to the holey bees Heriades and the scissor bees Chelostoma . All five genera were temporarily combined in the genus Osmia , but this is outdated.

Mason bees are among the most common solitary bees. They use glandular secretions and pieces of leaf or soil to produce building material for their cells in which the brood grows. They create these nests in a species-specific manner - for example in walls , rock crevices or in the ground as well as in stalks, in the dead wood of hollow branches or in corridors of wood-boring insects.

From nest building to larva and hatching

Building materials and brood food

A third of the 50 or so Central European species prefer pre-existing cavities . Some build in sandy soil or on stones, but at least a quarter also in empty snail shells or in the pulp of plant stems. The building material of the former and the "stone builders" is mainly mineral (sand, clay, stones), but partly also vegetable mortar (chewed pieces of leaf - to which the shape of the pine is then "adjusted"). Little is known about the "snail settlers", those in the marrow usually take pieces of leaf. Some species also bite off petals , such as Hoplitis papaveris , which, like Osmia maritima, digs sand holes.

The female supplies the future larvae of each cell with pollen and often some nectar . Then it lays an egg on the pollen store and seals the cell. As a rule, the cell closure is also the back wall of the next cell - so several cells are hidden behind a nest closure. The Osmia brevicornis, on the other hand, fills its nest tubes continuously with pollen, so their larvae grow up together.

Some mason bee species can be specifically promoted by setting up nesting aids . This not only counteracts the general decline in most solitary bees as a result of changes in the landscape, it also offers amateurs and experts interested in nature good opportunities to observe nature.

In contrast to sand bees ( Andrena spec. ), Mason bees rarely come together in large groups. A population density comparable to sand bees can only be achieved if many nesting blocks are set up together.

In the species Osmia inermis , O. xanthomelana and also O. mustelina , preliminary stages of social behavior can be observed.

Larva, pupation and flight times

The larva moults several times after hatching and eats the food supply for weeks before spinning into a cocoon and pupating. At the end of the metamorphosis , the flyable bee (imago) hatches from the pupa. The winter break can take place in different stages: some species overwinter as larvae, others as finished insects, which can then hatch in cool March.

Usually the males appear first and have to wait one to two weeks for the females to hatch later. This is presumably because the unfertilized eggs are laid last, so that the males can clear the nesting passage before the females. Most of the 50 or so Central European species only have one generation per year (“univoltin”). Their flight times are 1½ to 3 months long, but very different depending on the species:

Of the eight most important species, the O. cornuta ( horned mason bee ) begins in March / April; as a “eurytopic species” it is one of the “biotope generalists” who feel comfortable in many living spaces (including villages and the city ). The well-known Osmia bicornis ( red mason bee ) flies at least in April and May, while Osmia spinulosa and Hoplitis claviventris are on the move from June to August.

Modular nesting blocks also for the professional breeding of mason bees

Nesting blocks with 200 or 100 nesting passages
Nesting boards made of MDF with aisles of 8 mm / 6 mm diameter and approx. 15 cm in length

After the decline in bee pollination in agriculture due to the Varroa mite , the beetle beetle and other environmental influences such as the use of pesticides and the aging of the beekeeping structure, bumblebees and mason bees are increasingly used for pollination. Today, around 75% of the fruit-growing areas in Japan are pollinated by mason bees. Various providers therefore offer modular nesting aids for the red and horned mason bee. They consist of nesting boards with milled nesting passages of 8 mm / 6 mm in diameter and approx. 15 cm in length. The resulting blocks are connected with a tension belt or threaded rods, depending on the system.

In autumn, when the mason bees have pupated, the blocks are opened and cleaned so that the parasite infestation is reduced. Before cleaning the nesting boards, the cocoons are removed with tweezers, cleaned of feces, nesting material and parasites as well as pollen residues under cold water and stored in a cool place after drying. The individual boards are cleaned with a brush and hot water, also dried and only brought back to their destination together with the cocoons in spring.

Since the nesting blocks need weather protection, elongated mortar tubs are used in the plantations. They are set up at a height of about one meter or integrated into existing hedges. Small animal wire ensures protection from birds, colored differences are used to better orient the bees.

Parasites

Red mason bees

Like all solitary bees, mason bees are also affected by parasites. A quarter of the bee species are "brood parasites" or - parasites that lay their eggs in foreign nests. The offspring of these " cuckoo bees " feed on the larvae or the provisions found by the host bees. A number of mason bee species are hosts for the cuckoo bee genera Stelis and Dioxys .

The brood of the red mason bee is often attacked by the club wasp ( Sapyga clavicornis ) and the fruit fly ( Cacoxenus indagator ), as well as pied flyers ( Anthrax anthrax ) and mites ( Chaetodactylus osmiae ).

In addition to this frequent phenomenon, there are other parasites from the insect kingdom: Nature lovers can watch the metallic shimmering gold wasps (Chrysidinae) on the nesting blocks of mason bees as they "patiently" wait for a suitable moment to lay their own eggs.

Mason bee species (selection)

Others

The species Osmia bicolor was chosen as wild bee of the year 2013 on October 7, 2012 at the hymenopterists' conference in Stuttgart .

Individual evidence

  1. ↑ E. Scheuchl & W. Willner: Pocket dictionary of wild bees in Central Europe . Quelle & Meyer, 2016, ISBN 978-3-494-01653-5 , pp. 431 .
  2. ↑ Mason beekeeping
  3. ↑ Manual_der_Mauerbienenzucht
  4. ↑ parasites of the mason bee at naturgartenfreude.de, accessed on 4 May 2020th
  5. ^ The two-colored snail-shell bee , State Museum for Natural History Stuttgart from January 1, 2013 (accessed on January 31, 2013)

literature

  • May R. Berenbaum: bloodsucker, founder of the state, silk manufacturer. The ambivalent relationship between humans and insects . ISBN 3-8274-0078-3 .
  • Beetles and other insects . Hallwag paperback

Web links

Commons : Mason bees  - Collection of images, videos and audio files