Thursday, January 31, 2013

Biodiversity with Bees

It seems that many times, diversity in ability trumps raw talent, and it turns out that the trend holds in the area of ecosystem services as well.  Basically, the concept of ecosystem services is an attempt to quantify the good things nature provides for us so that they can be taken into account when calculating the true cost of a product or process.  Some examples of ecosystem services include clean air, soil nutrients for food production, and pollination of crops.  Brittain et al. looked at that last one in an article that appears in the most recent issue of the academic journal Proceedings of the Royal Society B: Biological Sciences. (Believe it or not, the Royal Society of London publishes journals with even longer names.)  It turns out that honeybees do a better job of pollinating almonds if other bee species are present (specifically, non-apis bees).  The authors were inspired to try almonds because it also works for sunflowers. 

In short, for crops like (commercial-scale) almonds, where the trees are planted in alternating rows of different varietals, honeybees tend to move more commonly up and down a row than between rows if left to their own devices.  The reasons for this behavior aren’t clear, but one hypothesis is that it happens because the next-nearest (good) flower tends to be in the same row.  In the case of almonds, that’s not good because you need the bees to fly between rows for successful pollination (and fruit set).  What the authors found was that the presence of other types of bees causes honeybees to change their flight patterns such that they fly between rows more often, thereby increasing pollination efficiency.  They suggest that when the non-apis bees are around (and visiting flowers themselves), two things happen because of the increased competition for nectar and pollen.  First, the next-nearest good flower for a honeybee might not be in the same row since a lot of the flowers have already been "emptied" by the non-honeybees.  Second, when the non-honeybees visit a flower, they might leave behind a chemical marker that the honeybees don’t like.  Both might contribute to the honeybees having to look farther for the next-nearest good flower, which is just as likely to be in the next row over as in the same row.  However, the authors aren’t completely sure about the causes.
This little guy, Osmia Lignaria, will tell your honeybees that it's OK to color outside the lines. Photo credit: Wikipedia 

It's important to note, however, the improved pollination would only be expected within certain man-made systems.  That is, if the trees weren’t planted in unnatural rows to begin with, the bees’ movement between trees would have been less biased even without the other bees (but the almonds would be harder to harvest mechanically).  

Isn’t it fascinating that honeybees’ flight pattern can be affected by the geometry of your garden and the presence of other kinds of bees?  Nature never ceases to amaze (me, anyway).  The article also points out another advantage of having other kinds of bees present—some species can forage at lower temperatures than honeybees, which means they can get to work earlier in the day, and also earlier in the season.  That can be especially important if you’re growing early-blooming fruits like apples and cherries in northern climates.

Since honeybees tend to go to the next tree in the line, planting your orchard like this might make your bees dizzy (but probably not).
The article doesn’t say anything about how the changes in movement affect honey production, but if it's pollination you're after, it looks like workplace diversity is important, even if your employees are insects!

Related links: the University of Arkansas has some advice on how to attract certain species of non-honeybees to your garden.


  1. If they are after cross pollination, why don't they alternate the trees in the rows when they plant the orchard, and then alternate the rows, kind of checkerboard style. Then it wouldn't matter which tree the bees go to next, as each tree would be next to one of a different variety.

    This isn't really a comment about the article, which is interesting...but I just used some of your honey yesterday and was amazed at how fruity it's flavor was! Must be some of the orchard flower flavors made their way in. Just had to mention it. And thanks for the honey, honey!

  2. That probably would work better for pollination. I think the orchards are designed pretty much for ease of harvest--so if the growers wanted to keep the varieties of almonds separate (I don't know if they do or not) and still use mechanized harvesting, the checkerboard pattern might complicate that.

    I notice the appl-ey flavor every time I taste the honey, too! I think the orchard flowers were probably one of their main sources of nectar for the few weeks they were in bloom. It's a shame the bees didn't make it through the winter, but I do like the honey. :-) Can't wait to start keeping bees again!