Can aphids learn to cope with the pressure of endophytic fungi in their food plants?

Abstract

Plant-endophyte associations can have major impacts on the dynamics of consumer interaction-webs but long-term effects of mycotoxins and the ability of herbivores to adapt to these toxins have not been studied. To understand the potential of aphids to cope with mycotoxins, we compared the life-history parameters for aphids conditioned for several generations on endophyte-infected plants with those of endophyte-naïve aphids on both endophyteinfected and endophyte-free grasses. Aphids conditioned on endophyte-infected plants produced more offspring during the first days of adulthood than endophyte-naïve aphids independent of the endophyte infection of the test environment. However, the endophyte-conditioned aphids tended to have a shorter lifespan, which resulted in similar numbers of total offspring produced for endophyte-conditioned and endophyte-naïve aphids. The difference in life-history parameters caused by the conditioning environment suggests that the effects of endophytes on herbivore life-history traits may represent an adaptive change that should be considered in future studies of endophyte-herbivore interactions. Keywords: Rhopalosiphum padi, Neotyphodium lolii, Lolium perenne, common strain, adaptation, long-term effects, microbes, endosymbionts, reproductive strategy, life-history traits