Attempting to predict the plant-mediated trophic effects of soil salinity: A mechanistic approach to supplementing insufficient information

Excessive soil salinity is a global and growing problem for agroecosystems. Changing weather patterns, land use patterns, and the use of salinized irrigation water are all exacerbating the threat of soil salinity. High concentrations of salts in the soils are well known for their (usually detrimental) effects on plants. However, very little is known about how those changes in plants will go on to affect the rest of the food web that relies on that host plant. In this review, we focus on how soil salinity may be altering plants and creating indirect (knock-on) effects on herbivorous insects, particularly those in agroecosystems. Our goal is to encourage research in this area and to determine if there are any general predictions to be made based on what is already known. Since the literature of salinity effects on herbivores in terrestrial systems is fairly scarce, we take an additional mechanistic approach to look at how saline soils affect plants and try to use that information to make predictions for herbivores and salinity. Specifically, we look at direct effects on plants and plant-mediated indirect effects of drought stress and heavy metals. While we were not able to determine any simple, generalizable predictions, we do use our review to develop several questions that could not only help produce new, insightful research, but may also help begin developing patterns in a seemingly unpredictable system.