Sodium is an essential element for all animal but not for plant life. This sets up a dynamic where animals that primarily consume plants have the potential to be sodium limited. Additionally, plants that uptake sodium may be subject to increased herbivory, but also have the potential to attract beneficial sodium-consuming partners. Anthropogenic activities have altered the sodium cycle, especially increasing sodium deposition through saline irrigation water and road salt. To test for the effects of sodium addition on herbivory, we conducted sodium press experiments in 5 North American grasslands.
Results/Conclusions
Sodium addition increased both soil and plant sodium at all sites. Grasses in sodium addition plots had significantly higher herbivore damage by leaf miners. Forbs with higher sodium concentration had significantly more chewing insect herbivore and fungal damage than those in control plots. These results highlight the potential of saline irrigation water to increase crop pest herbivory and the under-examined role of sodium as a limiting nutrient for plant consumers.