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Host‐specific aphid population responses to elevated CO 2 and increased N availability
Author(s) -
Sudderth Erika A.,
Stinson Kristina A.,
Bazzaz F. A.
Publication year - 2005
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2005.01006.x
Subject(s) - aphid , biology , population , botany , host (biology) , macrosiphum euphorbiae , biomass (ecology) , horticulture , agronomy , aphididae , ecology , homoptera , pest analysis , demography , sociology
Sap‐feeding insects such as aphids are the only insect herbivores that show positive responses to elevated CO 2 . Recent models predict that increased nitrogen will increase aphid population size under elevated CO 2 , but few experiments have tested this idea empirically. To determine whether soil nitrogen (N) availability modifies aphid responses to elevated CO 2 , we tested the performance of Macrosiphum euphorbiae feeding on two host plants; a C 3 plant ( Solanum dulcamara ), and a C 4 plant ( Amaranthus viridis ). We expected aphid population size to increase on plants in elevated CO 2 , with the degree of increase depending on the N availability. We found a significant CO 2 × N interaction for the response of population size for M. euphorbiae feeding on S. dulcamara : aphids feeding on plants grown in ambient CO 2 , low N conditions increased in response to either high N availability or elevated CO 2 . No population size responses were observed for aphids infesting A. viridis . Elevated CO 2 increased plant biomass, specific leaf weight, and C : N ratios of the C 3 plant, S. dulcamara but did not affect the C 4 plant, A. viridis . Increased N fertilization significantly increased plant biomass, leaf area, and the weight : height ratio in both experiments. Elevated CO 2 decreased leaf N in S. dulcamara and had no effect on A. viridis , while higher N availability increased leaf N in A. viridis and had no effect in S. dulcamara . Aphid infestation only affected the weight : height ratio of S. dulcamara . We only observed an increase in aphid population size in response to elevated CO 2 or increased N availability for aphids feeding on S. dulcamara grown under low N conditions. There appears to be a maximum population growth rate that M. euphorbiae aphids can attain, and we suggest that this response is because of intrinsic limits on development time and fecundity.