GUT PHYSICOCHEMISTRY OF GRASSLAND GRASSHOPPERS

We examined the pH and Eh of the digestive tract of 23 species of mixe d-grass prairie grasshoppers, and asked whether these traits were asso ciated with the species breadth and forb composition of their diets. W e report that the gut lumen of all grasshoppers was oxidizing and rang ed from slightly acid to neutral depending on the gut region and speci es. Although gut physicochemical conditions differed among species, th e differences were of small magnitude. Conditions were fairly uniform along the digestive tract, which suggests little or no regulation of p H or Eh. Gut conditions were independent of diet breadth and the perce ntage of forbs in the diet. These results suggest that physicochemical conditions of grasshopper guts are not highly regulated and are not i nfluenced by their most recent meal or by broad scale patterns of host -plant use. (C) 1998 Elsevier Science Ltd. All rights reserved.