PARENT SESSION
Poster Session # 9: Herbivory.

Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Latitudinal variation in herbivore densities and damage to plants in coastal salt marshes.

Ho, Chuan-Kai ^*,1, Salgado, Cristiano ^*,1, Dave, Nilam ^*,1, Pennings, Steven ¹, ¹ University of Houston, Houston, TX

ABSTRACT- Biogeographic theory predicts that plant-herbivore interactions are more intense at low versus high latitudes. Salt marshes along the Atlantic coast of the U.S. provide an ideal system to examine this theory because similar plant and animal communities occur across a wide latitudinal range from Maine to Florida. We tested two hypotheses: 1) herbivores are more abundant at low versus high latitudes, and 2) damage to plants by herbivores is greater at low versus high latitudes. Sampling was conducted monthly from June to September, 2002, at ten high-latitude sites (ME, MA, RI, CT) and ten low-latitude sites (SC, GA, FL). We measured herbivore damage to four plant species (Iva, Juncus, Solidago, Spartina) that occurred in both geographic regions, and measured herbivore densities (aphids, beetles, crabs, acridid grasshoppers, tettigoniid grasshoppers, hemiptera, snails) on each plant species. Results showed that 1) as predicted, herbivores were more abundant at low versus high latitudes for most plant species (Solidago was the exception), and 2) as predicted, damage by herbivores to plants was more intense at low versus high latitudes, for all four plant species. These results support the biogeographic theory that plant-herbivore interactions are stronger at low versus high latitudes.

Key words: latitude, saltmarsh, plant-animal interaction, herbivory