Symbiotic fungal endophytes control insect host-parasite interaction webs

OMACINI M; CHANETON, EJ; GHERSA, C.M.; MULLER,CB

NATURE

NATURE PUBLISHING GROUP

Lugar: Londres; Año: 2001 p. 78 - 81

0028-0836

Symbiotic microorganisms that live intimately associated withterrestrial plants affect both the quantity and quality ofresources1,2, and thus the energy supply to consumer populationsat higher levels in the food chain. Empirical evidence on resourcelimitation of food webs points to primary productivity as a majordeterminant of consumer abundance and trophic structure3±6.Prey quality plays a critical role in community regulation7,8. Plantsinfected by endophytic fungi are known to be chemically protectedagainst herbivore consumption9±11. However, the in¯uenceof this microbe±plant association on multi-trophic interactionsremains largely unexplored. Here we present the effects of fungalendophytes on insect food webs that re¯ect limited energytransfer to consumers as a result of low plant quality, ratherthan low productivity. Herbivore±parasite webs on endophytefreegrasses show enhanced insect abundance at alternate trophiclevels, higher rates of parasitism, and increased dominance by afew trophic links. These results mirror predicted effects ofincreased productivity on food-web dynamics12. Thus `hidden´microbial symbionts can have community-wide impacts on thepattern and strength of resource±consumer interactions.