Abstract
Changes in host plant quality, including foliar amino acid concentrations, resulting from global climate change and attack from multiple herbivores, have the potential to modify the pest status of insect herbivores. This study investigated how mechanically simulated root herbivory of lucerne (Medicago sativa) before and after aphid infestation affected the pea aphid (Acyrthosiphon pisum) under elevated temperature (eT) and carbon dioxide concentrations (eCO2). eT increased plant height and biomass, and eCO2 decreased root C:N. Foliar amino acid concentrations and aphid numbers increased in response to eCO2, but only at ambient temperatures, demonstrating the ability of eT to negate the effects of eCO2. Root damage reduced aboveground biomass, height, and root %N, and increased root %C and C:N, most probably via decreased biological nitrogen fixation. Total foliar amino acid concentrations and aphid colonization success were higher in plants with roots cut early (before aphid arrival) than those with roots cut late (after aphid arrival); however, this effect was counteracted by eT. These results demonstrate the importance of amino acid concentrations for aphids and identify individual amino acids as being potential factors underpinning aphid responses to eT, eCO2, and root damage in lucerne. Incorporating trophic complexity and multiple climatic factors into plant-herbivore studies enables greater insight into how plants and insects will interact in the future, with implications for sustainable pest control and future crop security.
Highlights
Host plant quality and suitability for herbivorous insects shapes the extent to which plants are attacked (Bernays and Chapman, 1994), and sudden improvements in host plant quality can lead to pest outbreaks (Barbosa et al, 2012)
This study investigated how mechanically simulated root herbivory of lucerne (Medicago sativa) before and after aphid infestation affected the pea aphid (Acyrthosiphon pisum) under elevated temperature and carbon dioxide concentrations. eT increased plant height and biomass, and eCO2 decreased root C:N
Aphids respond to changes in the amino acid quality of phloem sap, which has been shown to be affected by both global climate change (Harrington et al, 1995; Newman, 2003; Pritchard et al, 2007; Sun and Ge, 2011) and root herbivory (Johnson et al, 2012 2013)
Summary
Host plant quality and suitability for herbivorous insects shapes the extent to which plants are attacked (Bernays and Chapman, 1994), and sudden improvements in host plant quality can lead to pest outbreaks (Barbosa et al, 2012). Biotic and abiotic factors often induce changes in secondary metabolites that might deleteriously affect herbivores (Iason et al, 2012), but these can change the nutritional quality of plants, leading to increased susceptibility of plants to herbivores (White, 1984; Johnson et al, 2009). This is true for mobile herbivores that have short generation times and respond quickly to changes in host plant nutrition, such as aphids (Dixon, 1998; Douglas, 2003). Experiments were carried out to examine how elevated temperature (eT) and atmospheric carbon dioxide concentrations (eCO2), as well as simulated root herbivory, acted alone and together to affect foliar amino acids and plant susceptibility to aphids
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
