Abstract:
In tropical forests, herbivorous arthropods remove between 7% up to 48% of leaf area,
which has forced plants to evolve defense strategies. These strategies influence the palat-
ability of leaves. Palatability, which reflects a syndrome of leaf traits, in turn influences both
the abundance and the mean body mass not only of particular arthropod taxa but also of the
total communities. In this study, we tested two hypotheses: (H1) The abundance of two
important chewer guilds (‘leaf chewers’ and ‘rostrum chewers’), dominant components of
arthropod communities, is positively related to the palatability of host trees. (H2) Lower pal-
atability leads to an increased mean body mass of chewers (Jarman-Bell principle). Arthro-
pods were collected by fogging the canopies of 90 tropical trees representing 31 species in
three plots at 1000 m and three at 2000 m a.s.l. Palatability was assessed by measuring
several ‘leaf traits’ of each host tree and by conducting a feeding trial with the generalist her-
bivore Gryllus assimilis (Orthoptera, Gryllidae). Leaf traits provided partial support for H1, as
abundance of leaf chewers but not of rostrum chewers was positively affected by the experi-
mentally estimated palatability. There was no support for H2 as neither leaf traits nor experi-
mentally estimated palatability affected the mean body mass of leaf chewers. The mean
body mass of rostrum chewers was positively related to palatability. Thus, leaf traits and
experimentally estimated palatability influenced the abundance and mean body mass of
chewing arthropods on the community level. However, the data were not consistent with the
Jarman-Bell principle. Overall, our results suggest that the palatability of leaves is not
among the dominant factors influencing abundance and mean body mass of the community of chewing arthropod herbivores. If other factors, such as the microclimate, predation or fur-
ther (a-)biotic interactions are more important has to be analyzed in refined studies.
