Rodents versus endophytic fungi: do mice and voles recognize infected food in cafeteria tests?

This study aimed to examine the potential influence of toxic alkaloids produced by endophytic fungi, Epichloë typhina , on food selectivity of rodents from different trophic groups: the granivorous striped field mouse, Apodemus agrarius , the herbivorous common vole, Microtus arvalis , and the omnivorous house mouse Mus musculus . The fungal mycelium of endophytes can infest the seeds and vegetative parts of the plant to varying extents. Consequently, the alkaloids may be contained in both, causing toxicosis of differing intensity among herbivores from different trophic groups. Hypothesizing that these rodents avoid feeding on different parts of fungus-infected grasses to varying degrees, the following predictions were verified: (1) striped field mice prefer eating seeds over the green parts of plants, whereas common voles prefer eating the green parts over seeds; (2) striped field mice show a stronger preference for uninfected food when selecting among seeds than when choosing among green plant materials; (3) common voles exhibit greater preference for uninfected food when consuming the leaves than when consuming the seeds; (4) house mice show less differentiated responses. A total of 69 individuals from the three aforementioned species were tested in cafeteria tests. During 2 h trials, the animals could freely choose between seeds infected and uninfected with an endophytic fungus and the green parts of weeping alkaligrass, Puccinellia distans . Analyses revealed significant differences in food preferences and avoidance among the tested rodents, consistent with the above-mentioned predictions. Studying these interactions in wild rodent models provides valuable insights for basic research (understanding mechanisms and dependencies). Moreover, the findings of this study contribute to our knowledge about the mechanism by which fungal alkaloids in different food sources influences small wild mammals from various trophic groups, potentially affecting their foraging behaviour and dietary choices at the individual level. • Rodent species exhibit trophic-specific responses to endophytic fungal infection. • Endophytic fungi significantly modulate rodent foraging and food selection. • Apodemus agrarius (granivore) strongly avoids seeds infected with Epichloë typhina . • Microtus arvalis (herbivore) prefers uninfected leaf tissues over infected ones. • Mus musculus (omnivore) shows low discrimination for fungus-infected plant parts.