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Kas läiklehise pärna õienektar on mesilastele narkootilise toimega? Kui jah, kas siis ei tohiks antud liiki mesilastarude lähedusse istutada?

 

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läiklehise e. krimmi pärna nektar võib olla mesilastele kahjulik

Huvitav küsimus! Endal sellist kogemust ei ole, seepärast pöördusin Google poole. Leidsin selliseid seisukohti:

Tilia x Euchlora - toxic for bees:
http://www.righettiromano.it/file_pdf/scheda.665.pdf

Foorumi teema, kus on vastakaid arvamusi nii sellest, et läiklehine pärn on kahjulik kui ka sellest, et ei ole:
http://www.tree-care.info/uktc/archive/2003/msg04266

Põhjalik 1991. a uuring aadressilt www.apidologie.org, kus lk 8-9 on kirjas, et läiklehise e. krimmi pärna (Tilia x euchlora) nektar võib olla mesilastele kahjulik ja mõjuda surmavalt (vt tsitaadi lõpus olevat rõhutatud teksti):

Tsitaat:
Physiological, ethological and ecological
questions on the death of insects
visiting late flowering lime trees
The phenomenon of dead or dying bees
and bumblebees under late flowering lime
trees (such as the silver lime tree Tilia tomentosa
and the Crimean lime tree T x
euchlora) has been a subject of controversy
for several years. According to Madel
(1977) bee-toxic mannose, present in the
nectar of these lime trees, is responsible
for bee death. Until now, however, it has
not been conclusively proved that lime tree
nectar really contains mannose. To demonstrate
nectar toxicity, Madel fed 8 bumblebee
workers on 7 open flowers on a silver
lime tree branch for 12 h; no additional
food was offered. All bees died during the
experiment. As can be shown, they probably
died of hunger.

Assuming an optimal nectar production
by the 7 flowers, these flowers could only
have provided 1/20 of the chemical energy
required to keep 8 bumblebees alive for
12 h (Surholt et al, 1988). After a preliminary
paper-chromatographic analysis,
Madel then suggested that mannose was
present in the nectar of this lime tree. His
method, however, was not able to conclusively
identify mannose. Therefore, because
nearly all questions concerning this
phenomenon have been left open until
now, different groups of scientists from the
University of Münster and the Landwirtschaftskammer
Westfalen-Lippe initiated a
joint research program on this topic.
In July 1990 the death of bees under
lime trees was again observed at different
locations. This happened in particular under
solitary Tilia tomentosa and T x euchlora.
Here up to 200 dead insects were collected
per day per tree. Gas-liquid
chromatography techniques were first applied
to detect mannose in the nectar samples
from these lime trees. The separation
of mannose from other monosaccharides,
however, was far from satisfactory. A capillary
gas-liquid chromatography method
was therefore developed, which now allows
complete separation and determination.
The preliminary results were as follows:
no mannose was detected, a result
which was confirmed by enzymatic analysis.
Thus until now, no support has been
found for the "mannose toxicity theory".
There might, however, be special subspecies
or hybrids of Tilia tomentosa or T x
euchlora which are able to produce toxic
nectar. In addition, climatic and edaphic
factors should be taken into consideration;
but it seems probable that it is a very complex
combination of many different factors
that causes the death of the insects under
late flowering lime trees.