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Effect of species-specific microbial communities on lima bean defense following simulated herbivory

Lima bean EFN number and nectar produced have been found to increase upon induced damage. We were interested in the net effect of the soil microbial community on the expression of EFNs. We planted lima bean in lima bean-cultivated soil and tomato-cultivated soil. Half of each soil type was sterilized to examine whether the microbial community has a net positive or negative effect on EFN production, and whether that effect was species-specific. A subset of plants in each soil type was subjected to simulated herbivory to see if expression of induced defenses was affected by soil microbes. We found that damage had no effect on the expression of EFNs. However, sterilization significantly increased EFN number in lima bean-cultivated soil, suggesting that the costs of species-specific soil pathogens outweighed the benefits of mutualists. This interaction was lost the following week, when we found no significant interaction.