Diffuse interactions between two herbivores and constraints on the evolution of resistance in horsenettle ( Solanum carolinense )

Author： Wise Michael

Publisher： Springer Publishing Company

ISSN： 1872-8855

Source： Arthropod-Plant Interactions, Vol.4, Iss.3, 2010-09, pp. : 159-164

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Abstract

Interactions between plants and herbivores are considered “diffuse” if the ecological interactions between two species, or their evolutionary responses, differ depending on the presence of a third species. I looked for evidence of diffuse interactions among horsenettle (Solanum carolinense</i>) and two common herbivores. Plants experimentally protected from lace bugs (Gargaphia solani</i>) were twice as susceptible to attack from flea beetles (Epitrix fuscula</i>) once transplanted into the field. Thus, the selective benefit to horsenettle of resistance against lace bugs in nature would likely be diminished by increased attack from flea beetles. Moreover, the relative rank among horsenettle genotypes for resistance against flea beetles was changed by prior exposure to lace bugs. Thus, the genetic expression of resistance to flea beetles would depend on the “lace bug environment.” By affecting selective pressures or response to selection, these sorts of diffuse interactions in a plant-herbivore community can slow the host plant's evolution of resistance to its herbivores.