Performance of the legume-feeding herbivore, Colias philodice (Lepidoptera: Pieridae) is not Affected by Elevated CO2

Abstract

Presumably due to their association with nitrogen-fixing bacteria, the nutritional quality of legumes decreases less than that of non-legume C 3 plants when grown under elevated atmospheric CO 2 . Therefore, it seems likely that legume-feeding herbivores will be less adversely affected than herbivores of non-legume C 3 plants by anthropogenic increases in atmospheric CO 2 . When the legumes Medicago sativa (alfalfa), Trifolium repens (white clover), and Lotus corniculatus (birdsfoot trefoil) were grown under elevated (756 ppm) CO 2 , leaf nitrogen remained the same or increased, and C:N ratio did not change. Unlike most insects fed non-legume C 3 plants, Colias philodice (sulfur butterfly) larvae fed elevatedgrown M. sativa and T. repens did not exhibit reduced relative growth rate (RGR), and larvae fed elevated-grown L. corniculatus exhibited a nearly significant 37% increase in RGR. Pupal weight was unaffected by growth of host plants under elevated CO 2 . Relative nitrogen growth rate (RGRN) did not change for larvae fed elevated-grown M. sativa or T. repens, but increased by 34% for larvae fed elevated-grown L. corniculatus. These results suggest that legume-feeding herbivores will be relatively buffered against the adverse effects of elevated CO 2 typically experienced by herbivores of non-legume C 3 plants.

Pea aphid promotes amino acid metabolism both in Medicago truncatula and bacteriocytes to favor aphid population growth under elevated CO2

“…Typically, elevated CO 2 increases nodule number (+33%), nodule mass (+39%), and nitrogenase activity in legumes (+37%), and eventually leads to a 38% increase in N fixed from the atmosphere (Lam et al ., ). The enhanced biological N fixation (BNF) can compensate for decreases in plant N under elevated CO 2 and maintain the equivalent C/N of those plants under ambient CO 2 , which partially or even completely counteracts the adverse effect of elevated CO 2 on leaf‐chewing insects (Karowe, ; Karowe & Migliaccio, ). Thus, compared with those on nonlegume plants, enhanced BNF is favorable to leaf‐chewing insects fed on legume plants under elevated CO 2 .…”

Elevated CO2 decreases the response of the ethylene signaling pathway in Medicago truncatula and increases the abundance of the pea aphid

“…Elevated CO 2 reduces the nutritional quality of some nonleguminous C 3 plants by decreasing the N concentration (Ainsworth & Long, ; Ainsworth & Rogers, ), which may consequently increase the developmental time and reduce the fecundity and fitness of leaf‐chewing insects (Coll & Hughes, ). However, N concentrations in legumes were rarely affected by elevated CO 2 because of the enhancement of biological N fixation (BNF), which counteracts the adverse effect of elevated CO 2 on leaf‐chewing insects (Karowe, ; Taub & Wang, ; Karowe & Migliaccio, ). For a sap‐sucking insect like the pea aphid ( Acyrthosiphon pisum ), the increased BNF in legumes under elevated CO 2 increases available N and thereby increases aphid numbers (Guo et al ., ).…”

Responses of Insect Pests and Plant Diseases to Changing and Variable Climate: A Review

“…Phloem and xylem feeding insects such as the Hemipterans may be less affected by elevated CO 2 levels because they feed on plant sap, which is low in defensive compounds (Furstenberg-Hagg et al, 2013). Insect pests that feed on seeds also may be less affected by increased CO 2 levels because they maintain high levels of nitrogen in their reproductive system and hence have no need to acquire more nitrogen from the crops (Karowe & Migliaccio, 2011).…”