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Knowledge center Crop protection & disinfection Bumble bees How to protect bumblebees from heat How to protect bumblebees from heat
Written by Kevin van Kester | Last update: 18-6-2021
When the sun is very strong, the temperature in the greenhouse increases. This can cause the bumblebees in the crop to overheat. This has a negative effect on pollination and, in the worst-case scenario, bumblebees can die. Therefore, when using bumblebees during a warm period, a few points should be considered to prevent pollination problems. We list these points and give tips.
Avoid full sun
Make sure that bumblebees are not exposed to the sun when it's hot. Heat causes the bumblebees to tire more quickly. At a temperature between 28 and 32°C, they are less active and therefore pollination takes place less. At a temperature of 32°C or higher, they even stop flying.
Positioning bumblebee boxes lower
If you place the bumblebee boxes lower in the crop during a warm period, less sunlight can reach the bumblebee boxes. This creates more pleasant conditions for the bumblebees, making it less difficult for them during warm days.
Shade
Place bumblebee boxes on the shady side of the path to prevent overheating. If the crop does not provide sufficient shade, create shade yourself. Use a Styrofoam plate, for example, or place the bumblebee boxes in crates.
Avoid sources of heat
Avoid sources of heat on hot days and check that bumblebee boxes are not too close to heaters or other sources of heat. Also seal off the CO2 hoses that are in a radius of two meters around the bumblebee boxes.
Using extra bumblebees
At temperatures between 28°C and 32°C, bumblebees become less active, as indicated above. By using extra bumblebees, you will ensure that you still achieve the desired pollination effect by these temperatures.
Compensate for loss
The last point is not related to overheating, but it can cause pollination problems. In spring, the area outside the greenhouse is in bloom. Some of the bumblebee will therefore leave the greenhouse and will no longer return to the bumblebee hive. To compensate for this loss, use more bumblebees from April onwards.