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Got wind?
A major component of my PhD is understanding how weather can impact bee foraging and behaviour. There are many studies examining how temperature can impact bee activity, however other major envrionmental variables have often been over looked. One prime example is wind. The studies that have examined wind highlight that bee activity is reduced on windy days however haven't delved much deeper into why that might be the case.
Enter me and my super high tech wind speed experiment.
My aim: identify how increasing wind speed influences honey bee foraging behaviour and success.
How did I achieve this?
Here is the super high tech part. I created artificial flowers using laminated 'star' designs with a cut out pipette tip to act as a nectary (part of the flower which holds the sweet sweet nectar) stuck in the middle with the whole flower head stuck on a plastic straw.
Now there are actually two parts to this experiment. Part 1, which is the focus of this blog, is examining the direct affect of wind on the bee. Part 2, which is yet to be completed, will be examining the indirect affect of wind. What I mean by this is that when the wind blows not only does it buffet the bee, but it also causes the flowers to move. So part 2 will involve no wind, and only flower movement, but I will get to that later.
So we have our flowers, we now need our wind. Now I know I've already shown you some pretty high tech stuff already, with the flowers, but you wait for this next part. To generate the wind we employed the use of... FANS.
Lots of fans. With these fans we managed to create three different wind speeds, with level one being the lowest at 1.6m/s and wind speed 3 reaching the highest speed of 3m/s. This might not seem all that high to you, but for a tiny bee that's quite a lot of headwind.
So we have our flowers, we have our fans, now we need our bees. To cut a very long process short, we eventually managed to train the honey bees from the neighboring hives to forage on our artificial flowers, allowing the experiment to begin.
So what did we actually do?
We set up our flowers facing the fans in a shed outside our lab. When a bee entered the shed the door was shut behind her (this was to prevent any external wind) and when she landed on her first flower the timer and camera (as we videoed all bees) was turned on. We would film each bee for 90s and the wind speed she experienced was chosen at random. When the 90s were up, we would catch her, weigh her and then mark her with a paint pen (don't worry, it doesn't harm them, and it makes them look all colorful). We mark them to make sure we don't film the same bee twice. And trust me, once they learn about our sweet sweet flowers (literally), they constantly want to come back for more.
So that's the 'field' work bit. Once we have our videos we actually need to start collecting some actual data. From the videos we were able to break down the behaviour of the bee to a frame by frame basis. The behaviours we eventually focused on were:
Number of flower visits
Time spent flying
Handling time
Time spent per flower
Hesitancy to take off
A little explanation. Handling time is the total amount of time a bee spent foraging on a plant (this accounts for her locating the nectar, foraging, and then deiciding to move on) where as time per plant takes this into account and the time it took the bee to travel between each plant (it was the total number of plants visited/90s). Hesitancy we calculated as the time between when the bee stops probing for nectar and when she actually takes off from the flower.
What did we find?
When compared to when there was no wind the number of flowers visited decreased as wind speed increased. They spent much less time flying at higher wind speeds, and when we arranged the flowers so the bees could walk between they didn't walk at all at wind speed 3! Handling time increased with increasing wind speed, however not when the flowers were touching and finally the time spent per plant... you guessed it, increased with wind speed. Bees were also much more hesitant when taking off in higher wind speeds, which is super interesting because some studies have looked at landing dynamics, others at during flight dynamics but none have looked at how taking off is influenced by wind, and it's just as important!
What does this all mean?
Essentially what this study has shown is that bees don't cope all that well with wind. They forage on fewer flowers and just generally take much longer to achieve a lesser goal. It's unsurprising then that studies that have examined how many bees are present in windy conditions show that their numbers decrease in higher winds, there just isn't any point in foraging.
What this project has also shown is that you don't need a really impressive expensive lab to conduct some pretty fun and interesting experiments. All you need is some plastic flowers, fans and most importantly, some bees.
The future
So we now know that the direct effects of wind on honey bee foraging is pretty significant, now to investigate the indirect effects! Watch this space...
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