Everyone knows about the birds and the bees but what most people don’t know is when plant-pollinator relationships are abused by pollinators, plants can create their own signature blend of toxin-infused nectar.
In 2017, Barlow and her team of researchers discovered that the story of plants and pollinators was more complex than a simple tale of two parties providing a service for each other. They found that nectar robbers forced Aconitum sp., to create the perfect blend of nectar and toxic alkaloids, where nectar robbers are deterred but not mutualistic pollinators that are essential for plant reproduction.
Mutualistic pollinators include long-tongued bumblebees, like Bombus hortorum, who have acquired resistance to the toxic nectar of Aconitum sp. over evolutionary time. This is a direct result of both species evolving in tandem to each other or co-evolving (Barlow et al., 2017) But just how toxic is this nectar and are seemingly alkaloid resistant bumblebees actually immune or does Aconitum sp. harm its pollinators in the name of self-defence? Is this desperate measure all in vain? Barlow and her team set-forth to find out.
Barlow spent two years at the Royal Botanic Gardens, Kew in the United Kingdom, observing the visitors for two species of Aconitum flowers, A.napellus and A.lycoctonum. Over the years, the team noticed visits from B.hortorum, the long-tongued pollinator, held true to our typical pollinator story by always making contact with the flower’s stamen or stigma when collecting nectar. However, a short-tongued bumblebee, known as Bombus terrestris, never once contacted the flowers of any two species. Instead B.terrestris used its mandibles to rip open the galea of the flower. Once pried open, this helmet-like structure oozed out the desired nectar (Barlow et al., 2017).