Abstract
Rising global temperatures are associated with increases in the geographic range, population size, and feeding voracity of insect herbivores. Although it is well established that the plant hormone jasmonate (JA) promotes durable resistance to many ectothermic herbivores, little is known about how JA-mediated defense is influenced by rising temperatures. Here, we used the Arabidopsis-Trichoplusia ni (cabbage looper) interaction to investigate the relative contribution of JA and elevated temperature to host resistance. Video monitoring of T. ni larval behavior showed that elevated temperature greatly enhanced defoliation by increasing the bite rate and total time spent feeding, whereas loss of resistance in a JA-deficient mutant did not strongly affect these behaviors. The acceleration of insect feeding at elevated temperature was not attributed to decreases in wound-induced JA biosynthesis, expression of JA-responsive genes, or the accumulation of defensive glucosinolates prior to insect challenge. Quantitative proteomic analysis of insect frass, however, provided evidence for a temperature-dependent increase in the production of T. ni digestive enzymes. Our results demonstrate that temperature-driven stimulation of T. ni feeding outweighs the protective effects of JA-mediated resistance in Arabidopsis, thus highlighting a potential threat to plant resilience in a warming world.
Highlights
In the coming decades, global climate change is expected to increase the severity of multiple stresses on plants and other members of terrestrial ecosystems [1,2]
The rate at which insect herbivores consume food depends on the metabolic needs of the herbivore and on the quality of host tissue and efficacy of defenses deployed by the plant host [9,10]
Plants grown under control temperature (CT) conditions for eight weeks were acclimated for 48 h to test temperatures (CT or elevated temperature (ET)) and challenged with neonate larvae
Summary
Global climate change is expected to increase the severity of multiple stresses on plants and other members of terrestrial ecosystems [1,2]. The rate at which insect herbivores consume food depends on the metabolic needs of the herbivore and on the quality of host tissue and efficacy of defenses deployed by the plant host [9,10]. Because both plants and phytophagous insects are ectothermic organisms, it is critical to disentangle the influence of temperature on plant defense pathways from the physiological effects of temperature on the herbivore
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