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Goldenrod research season is underway

Posted: June 19, 2013

'Tis the season to study goldenrod-insect interactions.

Summer weather has finally arrived here in central Pennsylvania, which means much of the research in the Tooker lab has moved outside. This is a great chance for us ecologists to get a first-hand look at what’s really happening in our study systems and (not to mention get some vitamin D after being stuck inside the lab all winter).  Many of the students in our lab are working on projects related to sustainable agriculture, but a few of us have gone a different route and are lucky enough to belong to the goldenrod research team. This year Rosie and I are setting out to tackle some fun and challenging research questions about the chemical ecology of this perennial North American weed and its insect herbivores.

Tall goldenrod (Solidago altissima) is a fairly common plant with a diverse herbivore community, making it a popular study subject for many ecologists. In Pennsylvania, goldenrod sprouts emerge in late spring from an underground network of stems called rhizomes. Goldenrod plants are usually associated with old-field habitats and often grow in dense patches, sometimes growing to be several feet tall. In late summer, the plants produce the beautiful golden inflorescences, for which they are named. A common misconception about goldenrod is that its pollen is responsible for many people’s late-summer allergies. However, goldenrod plants are insect pollinated, and their pollen grains are too large and sticky to be carried by the wind.

Goldenrod plants host a diverse array of insect herbivores including several gall-inducing insects. Gall-inducing insects force their host plants to form novel, nutritive and protective tissues to house and or feed them. We still don’t know exactly how galling insects induce these plant galls but we hope to figure out the mechanisms someday. One of the goldenrod gallmakers we study in the Tooker lab is the goldenrod ball gall fly, Eurosta solidaginis. The gall fly adults emerge in the spring and the male flies perch on the tops of goldenrod plants producing a volatile emission to attract females. After mating, the female flies lay their eggs into the apical buds of the goldenrod plants and the developing larvae induce ball-shaped galls in the stems of the plants. Goldenrod plants have evolved a variety of both chemical and physical defense strategies against the gall flies. The Tooker lab’s goldenrod research team is working to better understand these defenses and the chemical interactions between the goldenrod and the flies. 

--Anjel Helms