It may be very variable in natural or semi-natural habitat, but what about intensively managed agricultural landscape? For example, in northern Germany there is almost nothing else than oilseed rape in some areas. Would honeybees (try to) maintain an almost variate pollen diet or would they increase the proportion of OSR pollen? What about the relation quality/quantity? Thank you.
Of course it depend on the availability of pollen source and diverisity in one hand. In the other hand the bees will invest lots of their time in securing pollens from different olant sources for couping harsh environmental seasons. by considering the previous issues you wll be able to judge about the pollen source and quantity
Hi Claudia, we hope that we can approach the topic you raised with our COLOSS "C.S.I. Pollen Study". We had a workshop last week focussing on this, and I think a very important parameter is also foraging range. It might be that in areas with low pollen availability bees need to fly further to receive their preffered amount of pollen. How this relates to pollen quality is, in my humble opinion, unclear at the moment.
The foraging distance for pollen collection is lower in complex habitats (1500 m) compared to more simple landscapes (1700 m) (Steffen-Dewenter & Kühn, 2003)
Thank you for your answers. Robert, any further information about this topic from the CSI Pollen group would be very interesting for me. Would be interesting also in the context of maize pollen, don't you think?
Claudia, there is some information available. I do not have all at hand but see:
Pohorecka et al., 2013: EFFECTS OF EXPOSURE OF HONEY BEE COLONIES TO NEONICOTINOID SEED–TREATED MAIZE CROPS.
In general I believe that maize pollen is not very attractive (and nutrient) for bees, but see also:
Darclet Teresinha Malerbo-Souza (2011) The corn pollen as a food source for honeybees
Dear Claudia, we provide georeferenced data of the pollen spectrum of honey samples for north-east Germany. The Institute for Bee Research Hohen Neuendorf provides the data, we do the georeferencing and mapping. There also data on landscape strukture in the agrarian landscape (biotop index). You can find maps and tables on http://geobee.jki.bund.de/index.php?id=12. I know, this tackes only part of your question... but it maybe a help Best Burkhard
An individual at the University of Guelph was developing/using a pollen library to identify nectar sources by identifying/quantifying pollen present in honey. It is possible they may have identified pollen sources as well; if not, they should be capable of producing a distribution of pollen types in a sample.
Thank you for all your answers, it seems that there is still work to do! Burkhard, great site! In fact it helps!
Dear Claudia, the best way for identifying the collected pollen species and for assessing the pollen species proportions is by installing pollen trap to the hive entrance. This device samples pollen loads of the worker bees returning to the hive. Since most pollen loads are building of a single plant species one can identify and sort them by this. For the identification you may use pollen catalog, or better (as I use to do) identify the visited flower species in the area around, collect these flowers' pollen and study it under the microscope. You'll find clear color differences among the pollen load species, which will ease the load sorting. For assessing the collected pollen species proportions install a pollen trap on an active hive for an hour, sort the pollen loads sampled according to species, count the number loads of each species and also weigh each species loads. The numbers of the species loads will give you the proportions of the flower species flight collections. The weight of the species' collected loads will give you the quantity proportions of the collected pollen species. You should check few hives on each location at a time, since each hive develops its own pollen preferences.
Hi Burkhard
The site you mentioned is not English. Are there some English articles?
Dear Gad, Thank you for your suggestion. We were thinking of general proportions, not of single hives. Something like "In an area with intense oilseed rape cultivation you still find 40% other crops. It was the question about the relationsship of quantity and quality of pollen, not as much the identification of single pollen types.
In my opinion and experience, you have to analyze the pollen flora of the place under study, then ,analyze the pollen charge of a number of individuals and finally analyze the cualitative- cuantitative pollen deposited in the nest.
The composition of the pollen flora in a determinate place depends on the species that are flowering and fluctuates between weeks in the same period of flowering. Generally the species in flower are represented in the pollen nests of the honey bees.
Dear Patricia. I don't understand what do you mean by "analyze the pollen charge of a number of individuals"? Do you mean sampling and identifying the plant species of few individual bees' pollen loads? But how could few bees' loads exhibit a representative sample of the field flower species? The pollen species preference differs among hives, hours of the day and days of the season. For an example see the attached graph of five hives' average pollen preference. This is included in my research from spring 1992 in Israel. The changes of pollen species percentages throughout the season represent both changes of the flower species bloom and bee preferences
I do not quite understand the main question Claudia. Pollen quality, in my humble opinion has to do with the food reward posed to bee, that is, its nutritional value. On the other hand, diversity of pollen and variety of sources of pollen environment hives, is what we are studying, as you say Robert in CSI Pollen (task he coordinates) and we have between the two tasks is enough to do. In terms of quantity, I had also understood, as happened to Gad, you meant the amount of pollen collected from each type is determined in the way he tells you. And again, from my point of view, all this must be taken into account, thus, needs to be done and I hope that gradually, within the CSI Pollen task, move forward on this.
The samples are made up loads of pollen in different colors, as they explain, each color usually corresponds to a unique composition of the same type of pollen, but the same color may correspond to different species and the same species have different colors.
On the other hand, as you said Robert, in our work and experience in agricultural fields, we see that corn is not attractive to bees.
Best wishes Claudia
It is possible, but you need a good sampling of pollen source of plants that surrounding the experiment. You also need a good sample of individuals, for calculate the average proportion of pollen, and thus you will have an average closer to the reality of the different plant species and how much pollen of each species is being carried by honey bees.
Best regards
Cristian
Dear all, thank you very much for the discussion. It seems that I didn't make the point clearly. My main question was about the relation between quantity and quality of pollen sources, not about the percentages of single colonies. That's why I wrote about maize, which has little nutritional value but is available in masses. And in beekeepers' discussions, at least in Germany, it is often referred to as a pollen source for bees.
The other example was the Oilseed Rape, which is better in quality but in some areas may be the only major source for pollen. So would bees try to maintain the variety of pollen sources or would they just stay on OSR?
Hope this is clearer now. Nonetheless, your answers gave me good feedback and points to consider. Thank you.
Helle dear Claudia, this is a good article for your question. In this paper the authors evaluating the diversity and quality of pollen and how it affect the healt of hones bees. I hope this article is interesting to you and will help you with your question. Regards.
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0072016
Cristian
Its been a while, but I found this, Claudia, that might be of interest for you:
https://www.researchgate.net/publication/259358621_How_far_do_honey_bees_fly_to_fields_of_Brassica_napus_oilseed_rape
Conference Paper How far do honey bees fly to fields of Brassica napus (oilseed rape)?
Thank you Robert! Very interesting, it helps actually for a study I am doing. Have a good time at the Spring Convention!
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