Environmental conditions and host plant origin override endophyte effects on invertebrate communities

Systemic fungal endophytes of grasses can produce high concentrations of alkaloids that are known to deter invertebrate herbivores and reduce their abundance, especially in agronomic grasses. Grass endophytes may also influence invertebrate community diversity and composition. Here, we examined in a common garden experiment with wild tall fescue plants and the agronomic cultivar Kentucky 31, whether infection by Neotyphodium coenophialum, the genetic background (origin) of the host plant, abiotic factors, and their interactions affected the invertebrate communities living on tall fescue. We collected a total of 18650 invertebrates from the 480 tall fescue plants, identified them to 97 morphological taxa (mainly to family level) representing five feeding guilds (herbivores, detritivores, omnivores, predators and parasitoids). In contrast to past literature, endophyte infection did not affect abundances of any taxon or feeding guild, or taxonomic diversity and the composition of the invertebrate community. Instead, the invertebrate community of native tall fescue appears to be primarily driven by environmental conditions and niche differentiation among taxonomical groups of invertebrates. We propose that community approaches are required to understand of the role of endophytes on arthropod abundances and diversity in nature. Keywords Endophytic fungi. Tall fescue. Invertebrate diversity and community structure. Functional guild. Herbivory. Genetic variation