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Exotic herbivores on a shared native host: tissue quality after individual, simultaneous, and sequential attack.
Sara Gómez1, Colin M Orians, Evan L Preisser
1Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA. sara.gomez@tufts.edu
Oecologia
|February 8, 2012
Summary
Two invasive insects impact eastern hemlock quality differently. Hemlock woolly adelgid (HWA) significantly increased amino acids, while elongate hemlock scale (EHS) had minimal effect, suggesting complex interactions in forest decline.
Area of Science:
- Ecology
- Plant Physiology
- Forest Science
Background:
- Eastern hemlock (Tsuga canadensis) is declining due to invasive herbivores.
- The combined effects of multiple herbivores on host plant quality are not fully understood.
- Invasive species interactions can have unpredictable impacts on ecosystem health.
Purpose of the Study:
- To investigate how hemlock woolly adelgid (HWA) and elongate hemlock scale (EHS) individually and jointly affect eastern hemlock's amino acid concentration and composition.
- To determine if HWA or EHS feeding alters host plant quality.
- To explore potential interactions between HWA and EHS on host plant physiology.
Main Methods:
- Eastern hemlock trees were infested with HWA and EHS, individually and jointly (simultaneously and sequentially).
- Foliage was analyzed for amino acid concentration and composition after one year.
- Plant quality was assessed by measuring changes in free amino acid profiles.
Main Results:
- HWA infestation dramatically increased total amino acid concentration by 330% after one year.
- EHS feeding alone had a negligible effect on host plant quality.
- A significant interaction indicated EHS may mitigate HWA's impact on foliage quality when co-occurring.
Conclusions:
- HWA significantly alters eastern hemlock's nutritional quality, contrary to expectations of resource depletion.
- The interaction between HWA and EHS suggests complex ecological dynamics influencing host plant response.
- Understanding these interactions is vital for predicting forest mortality and managing invasive species impacts.
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