European beewolf

Bee Wolf ( Philanthus triangulum )

The bee wolf ( Philanthus triangulum ) belongs to the family grave wasps Crabronidae in the insect order Hymenoptera ( Hymenoptera).

From about the middle of June, the black and yellow insects are observed. One can see these wasps on her big head, thicker in the middle part probes, the conspicuous grave bristles in the female bees and wolves on Schwirrflug, similar to that of hoverflies.

The body length of about bees big beewolf females is 13-18 millimeters, that of the male but only 8-10 millimeters.

Habitat

You can find the beewolf in large parts of Europe to Siberia to warm and dry heaths and poor grass, similar to the steppes. This biotope is a result of exposure by humans progressively back, so that the bees Wolf is becoming increasingly rare.

Food

As food for the larvae used in Central Europe apparently only the honey bee ( Apis mellifera). The Capture is done solely by the female. The prey is first visually identified and then tested odor by shaking at a distance of a few centimeters. ( The rapid attack takes place only on an object with fragrant bee, for example, in the experiment on a smeared with fragrant bee wooden blocks of similar size. ) The speed of the unexpected attack allows virtually no defense: The measures taken with the legs victims immediately with an engraving made by a fast-acting poison unable to move. Then pressed the bee wolf with its abdomen tip along the abdomen of the prey. This pressure on the honey stomach of the bee takes her mouth from a drop of nectar, the bees licks the wolf. For the subsequent transport it is rotated into the supine position and placed in sandy terrain in flight for probably only optically recovered nest. With his legs the bee wolf holds it down the prey. A typical behavior when targeting with the input tube is the stalling and back and forth movement in the air. The heavily laden grave wasp eventually disappears with the loot quickly in the soil.

Unlike the larvae to adult bees Wolves of nectar from the flowers of various plant feed. As described above, are used to chasing females also captured honey bees as nectar suppliers.

Reproduction

The females dig a tube into the ground, which can be up to one meter long. This ends in five to seven chambers, three to four, but sometimes up to six paralyzed honeybees are brought into the normally. These are used to feed the offspring, with future females a bee need more than the males.

For a long time it was assumed that the stunned bees are made ​​by the poison, which only has a paralyzing effect, durable and so do not spoil. According to the findings of the research group led by Erhard Strohm from the Biozentrum, University of Würzburg could be demonstrated through a series of experiments that the preservation is done by a special treatment of the bee by the bee wolf. Here, the bee wolf licked the bee with its mouthparts from intensive. Untreated, but stunned by the poison of the bee wolf Animals spoiled after a few hours ( mold ). Due to this special treatment, the bees several days remain unspoiled.

In slightly inclined or horizontal ground after each visit to the nest for protection from nest predators, such as various beetles or parasitic wasps, closed this. In the vertical area of ​​the entrance is kept open.

From the subsequently laid eggs hatch white, made -shaped larvae. After eating of the bees pupate this so skillfully on a silk stem that they touch the floor or walls; this will also prevent the doll, favored by moisture, attacked by fungi is. Approximately mid-June then digs the new generation beewolves from their den in the ground.

Protection of larvae by antibiotics

Recent research also reveals that the beewolf cultivated Streptomyces bacteria. Female beewolves cultivate these bacteria in specialized antennal gland reservoirs and apply them to the ceiling of the brood cells. Beewolf larvae later take the bacteria on, they spin into their cocoons and thus increase the probability of survival of the larvae. The bacteria produce antibiotic substances that protect the bees Wolf offspring from fungal and bacterial infections.

Enemies

The bee wolf is parasitized by the wasp Hedychrum rutilans.