Introduction

1. Invasive Plant-Pollinator Dynamics in Meadow NetworksOregon State UniversityEcoInformatic Summer Institute 2013Noelle Patterson

2. Introduction • Pollination Networks: A representation of the complex web of interactions between two distinct groups: plants and pollinators. • Pollination networks were studied in fifteen montane meadows in the HJ Andrews Experimental Forest region. • Pollination networks here include both native and invasive species. • Common invasive insect: Apismellifera(European honeybee) • Common invasive plant: Hypericumperforatum (St. John’s wort)

3. Study #1 Comparison of nonnative Apismellifera and native Bombylius major Apismellifera on Giliacapitata Bombylius major

4. -Apismellifera interactions reflect logistic growth. The %50 line corresponds with a G. capitata stem count of 333.6.-92.1% of Bombylius major interactions were with Giliacapitata; this is modeled in logistic regression poorly.

5. -In terms of Giliacapitata use, both Apis and Bombylius occupy the same niche.-However, Apismellifera pollinate in much higher numbers and have a broader overall diet than Bombylius.

6. Why so many honeybees? Apismellifera are a domesticated species whose population is supported by outside human help, giving them an advantage over competition. But- Bombylius major is a parasite of solitary ground nesting bees. Outside Apismellifera impacts… harmful or beneficial?

7. Study #2Hypericumperforatum and Bombus species • Hypericumperforatum (St. John’s wort) is a weedy plant native to Europe, W. Asia, and N. Africa which has become invasive in many areas including the Western Cascades. • Although many nonnative plants in the HJA are restricted to roadsides, H. perforatum was found in three meadows from the 2011 sites. • H. perforatum is a popular food source for bumblebees in the late summer season.

8. A strong correlation exists between the amount of H. perforatum in the meadows and the proportion of pollination visits Bombus made to H. perforatum. • Point: Bombus species appear to have a preference for invasive Hypericumperforatum

9. Good news: the variety of Bombus plant partners does not decrease due to H. perforatum presence. The percentage of available flower species pollinated by Bombus is found in each round as an average of meadows with H. perforatum and neighboring meadows without H. perforatum.

10. Bumblebees: following the flower? During rounds 4 and 5 when H. perforatum is abundant, significantly more Bombus are found in meadows containing or nearby H. perforatum.

15. Conclusion • Invasive species such as Apismellifera and Hypericumperforatum have important roles within the pollination networks at the HJ Andrews forest. • Apismellifera is an important pollinator, but its volume of interactions may present competition to insects with overlapping niches like Bombylius major. • Hypericumperforatum has become an significant part of late season Bombus diets and could affect their distribution and where they winter over. • Much work must still be done exploring the relationships between insects, plants, and the entire network to gain a better understanding of these rich ecosystems.

16. Thank you To the EISI mentors who made this summer possible and to my great pollinator crew!