Image: The butterfly European Skipper (Thymelicus lineola), photo by Ole Martin.
A group from Aarhus University, Denmark discovered that insects leave DNA traces on the plants that they visit. Their discovery opens up a whole new way of identifying insect-plant interactions, tracking pollinators – especially endangered ones, and managing pest species.
Doctors Philip Thomsen and Eva Sigsgaard discovered that flowers can act as passive DNA collectors that store data about their visitors. The two had suspected that DNA is probably more common in the environment than already known, but were surprised by the amount of information they were able to glean from the flowers they studied. From the seven flower species they sampled, the researchers found traces of 135 different species of butterflies, moths, bees, flies, beetles, aphids, plant bugs, spiders and more.
Hundreds of insect species visit flower-rich habitats like meadows, but tracking which insects visit which flowers poses a considerable challenge.
“I have worked with DNA from water and soil samples for several years and have often thought that DNA is probably much more common in the environment than would initially imagine. With this study we wanted to test if eDNA from flowers can reveal which insects the flowers have interacted with”, says Thomsen, who heads a research group focusing on eDNA; the DNA found in the environment.
This method opens up completely new possibilities of studying the interactions between specific plants and insects.
Their method also holds promise in the management of endangered species like wild pollinators, which is an urgent task in the face of sharply declining insect populations. Several wild bees and butterflies populations, for instance, have decreased significantly in recent decades and many species have even become locally extinct (sometimes for rather surprising reasons).
“The eDNA method might provide a comprehensive overview of the insects involved in the pollination of various plants. Earlier the focus has almost entirely been on bees, butterflies and hoverflies, but we have found DNA from a wide range of other insects such as moths and beetles that may in fact also be important pollinators” says Thomsen.