Early Permian insect folivory on a gigantopterid-dominated riparian flora from north-central Texas

Abstract

Quantitative analysis of 11,562 cm 2 of foliar surface area from an Early Permian flora from north-central Texas reveals that 2.6% was removed by insect folivores. Of the 1346 foliar items analyzed, 31.8% were attacked by insect folivores. This Permian insect herbivory approximated one-third the level in modern tropical to temperate forests. Three taxa of Gigantopteridaceae exhibited disproportionately high insect consumption levels, ranging from 3.1 to 4.4% of leaf area, and attack frequencies of 39.6 to 82.8% —levels comparable to taxon-specific values for modern woody dicotyledonous angiosperms. Qualitative analysis of folivory type also indicates that five of the eight categories of herbivore damage occurring on this flora were confined to or overwhelmingly represented on Gigantopteridaceae, suggesting preferential host specificity for Gigantopteridaceae by insect folivores. By contrast, other pteridophylls, conifers, cycadophytes, and two taxa of uncertain affinity, showed low levels of leaf area removal and attack frequencies. The Gigantopteridaceae, an enigmatic group of Permian plants with large, megaphyllous foliage, foreshadowed physiognomic attributes occurring in later angiosperms. Both groups had similar consumption patterns and intensities by insect folivores. In this moderately diverse Early Permian flora, insect folivory was significant, at least in one riparian environment outside the Euramerican coal-swamp ecosystem, indicating that modern modes and magnitudes of insect consumption of vascular plant tissue were in place during the Late Paleozoic.