PARENT SESSION
Poster Session #55: Plant-Animal Interactions II.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Fungal infection in a native bunchgrass: effects on plant palatability.

Maas, Martha^*,1, Fowler, Norma¹, ¹ University of Texas, Austin

ABSTRACT- Nassella leucotricha is a native, perennial bunchgrass common in the grasslands and savannas of central Texas. Nassella is frequently infected by Atkinsonella texensis, an epiphytic fungus in the tribe Balansiae. Infection may reduce host plant palatability, thereby reducing the amount of tissue removed by insect herbivores. To test this hypothesis we conducted a field experiment at Pedernales Falls State Park in an area that contained both healthy and infected plants. Because infected plants were commonly found growing under tree canopies, we established plots beneath 40 randomly selected trees. We then randomly selected two or three infected plants in each plot and located each infected plant's nearest healthy neighbor. From May to August 2001, we examined plants to determine the proportion of leaves with evidence of insect herbivory. We then calculated the effect of infection status and plot (i.e., tree) on the proportion of leaves that were damaged. For each month, we found that infection did not reduce the amount of tissue removed by insect herbivores. However, plants differed significantly in the degree of herbivory among plots. Therefore, a plant's location was more important in determining tissue loss than its infection status. This is one of the first studies to examine the palatability of infected plants in a natural setting and to describe patterns of insect herbivory in this region.

KEY WORDS: nassella leucotricha, fungal infection, palatability, insect herbivory