Phloem phytochemistry and aphid responses to elevated CO2, nitrogen fertilization and endophyte infection. (7th April 2014)

• Record Type: Journal Article
• Authors: Ryan, Geraldine D.; Shukla, Kruti; Rasmussen, Susanne; Shelp, Barry J.; Newman, Jonathan A.
• Is Part Of: Agricultural and forest entomology. Volume 16:Number 3(2014:Aug.)
• Page Start: 273
• Page End: 283
• Publication Date: 2014-04-07
• Subjects: Insect pests -- Control -- Periodicals; Agricultural pests -- Control -- Periodicals; Forest insects -- Control -- Periodicals; 632.7
• DOI: 10.1111/afe.12055
• Languages: English
• ISSNs: 1461-9555

Abstract

<abstract abstract-type="main" id="afe12055-abs-0001"> <title>Abstract</title> <p id="afe12055-para-0001"> <list id="afe12055-list-0001" list-type="order"> <list-item id="afe12055-li-0001"> <p>Rising atmospheric CO<sub>2</sub> has been shown to alter plant nitrogen metabolism, growth and secondary chemistry. We hypothesized that altered aphid performance under elevated CO<sub>2</sub> is linked to phloem nitrogen chemistry.</p> </list-item> <list-item id="afe12055-li-0002"> <p> <italic>Rhopalosiphum padi</italic> performance on endophyte‐infected or uninfected tall fescue was examined under three levels of CO<sub>2</sub> (ambient, 800 and 1000 p.p.m.) and high and low nitrogen fertilization. Ethylenediaminetetracetic acid‐facilitated exudation was used to sample phloem sap, followed by quantification of relative amino acid concentrations using reverse‐phase high‐performance liquid chromatography.</p> </list-item> <list-item id="afe12055-li-0003"> <p>Aphid abundance was reduced at 800 p.p.m. relative to ambient CO<sub>2</sub> but returned to baseline at 1000 p.p.m. The density of aphids was reduced in both the elevated CO<sub>2</sub> treatments. Aphids were unsuccessful at colonizing endophyte‐infected plants, possibly as a result of the presence of loline alkaloids.</p> </list-item> <list-item id="afe12055-li-0004"> <p>Multivariate analysis showed that certain groups of phloem amino acids were altered by nitrogen fertilization and CO<sub>2</sub>. We found that four amino acids (valine, arginine, glutamine and aspartate) were correlated with aphid performance. These findings partially explained the effect of plant nitrogen fertilization and elevated CO<sub>2</sub> on aphids.</p> </list-item> <list-item id="afe12055-li-0005"> <p>The present study represents a first step toward providing a mechanistic explanation of the aphid performance changes that may result from rising atmospheric CO<sub>2</sub>.</p> </list-item> </list> </p> </abstract>