A new regime of herbivory from diverse plant-arthropod interactions from the Middle Jurassic of northeastern China

Qualitative and quantitative evaluation of insect herbivory is important for understanding the complex and diverse plant-insect associations in terrestrial ecosystems during the mid Mesozoic. We examined 2503 plant specimens from the Mid-Jurassic (Callovian, 165 Ma) Jiulongshan Formation, a gymnosperm-dominant, fern subdominant plant assemblage at Daohugou, northeastern China, where 149 species/morphotypes from 11 plant groups were identified. Based on the functional feeding group-damage type (FFG-DT) system, we detected a richness of 11 FFGs and 78 DTs, frequency of 2329 DTs, 8045 feeding event occurrences, and herbivory index of 3.27 %. Major consumption occurred on broad-leaved of bennettitaleans, accounting for half of all herbivory indicated by multiple indices, and ginkgoaleans, less so for narrow-leaved of conifers. The top-four feeding groups were margin feeding, piercing and sucking, oviposition, and galling; all groups displayed a pattern of narrow DT functional-breadth (22.22 %) and twofold increase of broad DT functional-breadth (48.15 %). Physical plant defenses were found on the most herbivorized plant host implying trade-offs between host physiology and insect herbivory. Compared with other gymnosperm-dominated assemblages, the elevated richness and intensity of Daohugou herbivory indicates a new regime of resource consumption that occurred by late Middle Jurassic time associated with predator and especially parasitoid diversification.