2016 update: Aphid addition and exclusion

Ants tending Aphis echinaceae

Aphis echinaceae is a specialist aphid that is found only on Echinacea angustifolia. It feeds on sap in Echinacea leaves, and can also be found on flowering heads. This aphid also attracts “ant bodyguards”, which protect the aphids from predation, and in the process may also fend off other potential herbivores. Prior studies by Team Echinacea members have demonstrated that aphid presence does not lead to significant changes in plant fitness in observational studies, although in controlled experiments aphid presence does affect herbivore damage. Furthermore, inbred plants are more susceptible to aphid presence than outbred plants.

In 2011, Katherine Muller designated a sample of 100 plants in experimental plot 1 for aphid addition or removal. The presence or absence of these aphids is maintained by team members two to three times per week. In summer 2016, aphid levels were assessed and maintained 14 times on 70 of these plants (addition on 33, exclusion on 37) from early July until early August. In September, Amy Waananen recorded signs of senescence in the leaves of treatment plants. This data can be combined with data from our common garden measuring data to explore the richness of the Echinacea-aphid relationship.

Start year: 2011

Location: Experimental Plot 1

Overlaps with: Phenology and fitness in P1

Data collected:

• Aphid counts for each treatment plant on each observation day, on paper
• Leaf senescence data, recorded on paper
• Initial and final assessment of aphid counts on treatment plants, recorded on paper
• Paper records stored in ‘Aphids 2016’ binder, currently at Chicago Botanic Garden
• Aphid counts also included in p1 measuring data

Products:

• 2016 paper by Katherine Muller and Stuart on aphids and foliar herbivory damage on Echinacea
• 2015 paper by Ruth Shaw and Stuart on fitness and demographic consequences of aphid loads
• 2015 poster by Daniel Brown and Kyle Silverhus (Lake Forest College) on achene and seed set differences on treatment plants

You can read more about the aphid addition and exclusion experiment, as well as links to prior flog entries mentioning the experiment, on the background page for this experiment.