Insect herbivory immediately before the eclipse of the gymnosperms:The Dawangzhangzi plant assemblage of Northeastern China

The Early Cretaceous terrestrial revolution involved global shifts from gymnosperm-to angiosperm-dominated floras.However,responses of insect herbivores to these changes remain unexamined.We evaluated 2176 highly sampled plant specimens representing 62 species/morphotypes from the 126 Ma Dawangzhangzi plant assemblage of Northeastern China.Our study consisted of horsetails,ferns,ginkgoaleans,czekanowskialeans,conifers,and an angiosperm.Their herbivory was evaluated by the functional feeding groups of hole feeding,margin feeding,and surface feeding(ectophytic feeders);piercer and suckers,and ovipositing insects(ectoendophytic feeders);mining,galling,and borings(endophytic feeders);and pathogens,collectively constituting 65 damage types(DTs).The plant assemblage was assessed for herbivory richness by DT richness,component community structure,and DT specialization on plant hosts;for herbivory intensity,it was evaluated for DT frequency,herbivorized surface area,and feeding event occurrences.Using feeding event occurrences,the data supported seven species/morphotypes as most intensely herbivorized:Liaoningocladus boii(76.6%),Czekanowskia sp.1(8.4%),Czekanowskia rigida(4.10%),Lindleycladus lanceolatus(3.5%),Ginkgoites sp.2(2.0%),Podozamites sp.1(1.1%),and Solenites sp.1(0.9%).The most herbivorized taxa were pinaleans(conifers),then czekanowskialeans,and lastly ginkgoaleans;the monodominant component community was the conifer Liaoningocladus boii.DT host specialization levels were low.The plant assemblage had an overall low 0.86%of foliage removed by herbivores,explained by physical and chemical antiherbivore defenses,and parasitoid attack.Although Paleozoic,gymnosperm-dominated assemblages had greater herbivory,component community structure of the three most herbivorized taxa are more similar to modern bracken fern and willow than modern gymnosperm taxa.

Cretaceous ants shed new light on the origins of worker polymorphism

Dear editor,Polymorphism refers to two or more clearly different phenotypes coexisting in the population of a species. It has been observed and studied among ants, bees, wasps, termites,dung beetles and stag beetles (Trible and Kronauer, 2017;Zhao et al., 2019). Size and shape variation of these holometabolic insects, especially ants, usually happen in larval development rather than adult stage.