Honeydew

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Bark lice of the genus Cinara that produce honeydew on the perennial wood of the common spruce

Honeydew is a sugary excretion product of various Schnabelkerfe (Hemiptera), especially the aphids (Aphidina), scale insects (Coccina), leaf fleas (Psyllina) and whiteflies (Aleyrodina) as well as various cicadas (Auchenorrhyncha). These insects feed on the sap from the sieve tubes of various plants. Due to the high pressure in these tubes, the animals absorb a lot of liquid and release it again in the form of honeydew.

Honeydew is also known under the name Meltau , not to be confused with powdery mildew .

A liquid similar to honeydew can escape from cereal grains infected by the ergot fungus .

Food for insects

An ant takes a Honigtautropfen at a bark louse on

Honeydew is a popular food source for various insects that feed on the sweet juice or use it as complementary foods. It is known that ants (Formicidae) beg for honeydew , which keep aphids like dairy cows and also protect them from predators. Most other insects, such as many Diptera (Diptera) and Hymenoptera (Hymenoptera), lick from the honeydew of leaves or needles, where it can form a thick and sticky film.

If insects do not harvest it, the sugary juice is rapidly from Rußtaupilzen populated. These fungi do not damage the plant directly, but can hinder photosynthesis .

Even on vehicles parked under trees that are heavily populated by aphids in the warm season, honeydew can be seen as a sticky film after a few hours.

However, since many crops with pesticides are treated, the honeydew could also for insects dying contribute.

Analysis of the components

For a reliable qualitative and quantitative determination of the constituents of honeydew place after an appropriate sample preparation the HPLC and the coupling of gas chromatography with mass spectrometry application. When fresh, honeydew is clear. It is rich in sugars, especially fruit , grape and normal sugar ( sucrose ), as well as maltose , fructomaltose and melezitose as well as other oligosaccharides in smaller quantities. In addition, the honeydew contains ferments , organic acids, vitamins and adenosine phosphates .

Certain Honigtaue contain bienenunverträgliche or toxic components that are not contagious Black Addiction ( honeydew disease trigger), which is manifested by hair loss in bees is black whereby the body of the bee, which can be treated by laying of hives to a pollen-rich site.

Honeydew and forest honey

Uncovering a honeycomb with dark honey made from honeydew

Honey bees occasionally collect honeydew instead of nectar . This then forms the basis for various types of honey , which are known as leaf, fir or forest honey . The color and aroma of these honeys vary greatly depending on their origin, especially with forest honeys from fir and spruce trees . Some species of bumblebee also collect honeydew.

The forest honey always contains a certain amount of the sugar type melezitose . This depends on the metabolism of the host tree ( phloem sap ) and the fermentation by the various species of bark lice . So stands z. B. the spotted larch bark aphid ( Cinara laricis ) suspected of producing a lot of melezitosis. If the proportion of this triple sugar exceeds 10 to 12 percent, the honey will already candy in the honey chamber of the beehive (from the bottom of the honeycomb cell). So it can no longer be harvested or only partially and with significantly increased effort. Such honey is then also known as melezitose honey or cement honey.

literature

  • Edmund Herold, Karl Weiß: New beekeeping school. Theoretical and practical basic knowledge. Ehrenwirth, 1995, ISBN 3-431-02739-3 , pp. 318-324.
  • Gerhard Liebig: The forest costume. Origin - observation - prognosis. Self-published, Stuttgart 1999, OCLC 868211160 .
  • Heinz Ruppertshofen: The humming forest. Forest beekeeping and forest hygiene. Combined biological forest protection. Ehrenwirth, Stuttgart 1995, ISBN 3-431-02280-4 , pp. 160-230.

Web links

Commons : Honeydew  - album with pictures, videos and audio files
Wiktionary: honeydew  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ Ant milks aphid. In: gfoe.org . Retrieved August 12, 2019 .
  2. ↑ Stephanie Kusma: Pesticides in honeydew can endanger beneficial insects. In: nzz.ch . August 11, 2019, accessed August 12, 2019 .
  3. ↑ Miguel Calvo-Agudo, Joel González-Cabrera, Yolanda Picó, Pau Calatayud-Vernich, Alberto Urbaneja, Marcel Dicke, Alejandro Tena: Neonicotinoids in excretion product of phloem-feeding insects kill beneficial insects. In: Proceedings of the National Academy of Sciences. 2019, doi : 10.1073 / pnas.1904298116 .
  4. ↑ C. Ni, B. Zhu, N. Wang, M. Wang, S. Chen, J. Zhang, Y. Zhu: Simple column-switching ion chromatography method for determining eight monosaccharides and oligosaccharides in honeydew and nectar. In: Food Chem. 194, Mar 1, 2016, pp. 555-560. PMID 26471592
  5. ↑ MK Dhami, R. Gardner-Gee, J. Van Houtte, SG Villas-Bôas, JR Beggs: Species-specific chemical signatures in scale insect honeydew. In: J Chem Ecol. 37 (11), Nov 2011, pp. 1231-1241. PMID 22089823
  6. ^ Friedrich Pohl : Bee diseases. 2nd Edition. Kosmos, Stuttgart 2005, ISBN 3-440-10407-9 , p. 135 f.
  7. ↑ Black addiction. Bayer Vital GmbH, archived from the original on October 19, 2016 ; accessed on November 17, 2017 .