Now that the energy transition is being accelerated due to current conditions, the need to switch to other light sources has suddenly become much more urgent. Great strides have already been made in researching the light spectra and light intensity and how they affect plant growth.
However, for crops in which pollination plays a crucial role in good yield and quality, knowledge about the functioning of pollinating insects under certain light conditions is still lacking, even though they can play an essential role in the dark winter months.
Within the project 'LEDs pollinate,' funded by 'Kas als Energiebron,' researchers have looked at how bumblebees and experimental hoverflies behave under different light spectra in a background of limited daylight such as on a Dutch winter day. It became clear that the bumblebees strongly prefer the spectrum with a lower proportion of red light. Approximately 70% of the bumblebees flew to the greenhouse section with less red light in the spectrum. In contrast, there was no preference for a greenhouse section under natural light conditions, and they flew around randomly.
In the cage experiment with six different light spectra, the bumblebees foraged only under the spectrum that mimicked daylight (B:G:R:FR 22:26:26). The hoverflies suitable for pollinating soft fruit crops did not distinguish between the different spectra and foraged under all light conditions. With these initial results, growers can already gain insight into the requirements they should set for their new lighting plans.