New plant cultivars are bred to optimise flower colour or size, foliage colour and density, and particular form. But could these selection preferences mean they’re not as good as a food source for pollinators?
Current research in California and Canada is comparing species native plants with native plant cultivars to see whether popular cultivars provide as much nutrition for their pollinators. Pollinators, such as different bee species, are adapted so that they emerge when their preferred food sources are flowering. However the availability of species plants is often reduced when a larger-flowering or more prolific cultivar comes on to the market and these cultivars are all cloned plants, which reduces genetic diversity. Is there an ecological impact from these plants, and do they compromise the forager’s food source?
Researchers at the Mt Cuba Centre (University of Delaware) are looking at both the diversity of foraging insect herbivores and also the nutritional value of various pollen sources. Dr Douglas Tallamy and his team are comparing species and cultivars of a range of woody plants to look at the number and diversity of insects that visit them. Dr Deborah Delaney is studying both species and cultivar plants of beebalm (Monarda species) and also tickseed (Coreopsis species) to see whether their individual ‘pollen kit’, the oily layer that contains bee attractants, is similar and whether each provides similar levels of carbohydrates and proteins. Although humans can’t smell the pollenkit, it is essential for bees to be able to locate those important food plants. It’s possible that although newer bred cultivars of native plants might look similar, they might have a pollenkit that’s different enough that it doesn’t attract local pollinating insects.