Hi all
We all have observed honey bees collecting substances from odd sources, including carcasses, compost piles, manure, rank water, etc. and have thought: what are they after? A new study just out, the lead author of which is Vanessa Corby-Harris, summarizes what is and isn't known about honey bee foragers' ability to discern the value of collectable substances:
if nurses assessed the quality of pollen diets, choice experiments would indicate higher
consumption of the more nutritious pollens compared to the less nutritious pollens. We
therefore conducted a series of experiments in nurse-aged honey bees to explore the connection
between pollen nutrition and choice. We first catalogued the nutritive properties
and plant taxon richness for three different pollens collected by honey bees. We then tested
whether nurse bees chose more nutritious pollens over others. We also conducted similar
tests using supplemented pollen and liquid diets to further test whether nutrition plays a
role in choice. Although the nutritional value of the three pollens differed, nutrition did not
influence choice. This suggests that, although certain pollens provide a greater benefit per
unit of consumption, honey bee nurses either cannot or do not discriminate among pollens
based on nutrition.
ΒΆ
So, when bees aggregate on (to us) odd resources, the question is, what is the stimulus/response going on, if not protein or other nutrients? One interesting point is that the main source of food value of pollen lies inside the grains which cannot be accessed by foragers, and generally require digestion by nurse bees to be utilized.
Further, the nurses which presumably benefit from the protein content, cannot evaluate its relative merit either. Something on the outside of the pollen or other substances must be attractive to foragers and could be unrelated to its relative value as food.
For example, some flowers display bright colors which attracts pollinators but does not correlate at all to the actual reward. Some flowers even spoof pollinators and offer no rewards.
Corby-Harris states:
foraging for resources based on the chemical profile of the pollen surface could disconnect the
needs of the nurses from those of the foragers, as the nutrients most important to nurses are
more abundant on the inside of the grain.
But even the nurses seem to be unable to evaluate food quality. Corby-Harris concludes that: "nutritional value plays a minimal role in nurse bee diet choice."
SOURCE:
Corby-Harris V, Snyder L, Meador C, Ayotte T (2018) Honey bee (Apis mellifera) nurses do not consume pollens based on their nutritional quality. PLoS ONE 13(1): e0191050. https://doi.org/10.1371/journal.pone.0191050
***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software. For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html
|
