MEALYBUGS AND OTHER SCALE INSECTS OF EARLY CRETACEOUS ANGIOSPERMS

Very little is known about feeding associations between the earliest angiosperms and their insect herbivores on megafloral material. One particular functional feeding group, piercer and suckers, consists of fluid–feeders representing an inconspicuous and underappreciated mode of herbivory that can provide new data on the evolution of deep-time ecological associations on particular clades while also indicating host-plant preferences of these insect herbivores. Studies of modern piercer and suckers on plants indicate that up to 50 percent of photosynthate is removed by Hemiptera such as cicadas, aphids, scale insects, whiteflies, planthoppers, and true bugs, indicating their ecological importance. While previous studies have documented fossil piercing-and-sucking herbivory, most were unable to identify culprit insect taxa. Nevertheless, evidence of scale-insect impression marks, and highly patterned punctures made by piercing-and-sucking insects, can indicate the systematic affinities and relationships of these insect herbivores. We report the earliest instances of piercing and sucking among the earliest angiosperms as evidenced by scale insect impression marks and covers, puncture patterns, and body fossils such as a mealybug from the Lower Cretaceous Rose Creek Flora (Dakota Formation, ca. 103 Ma) in southeastern Nebraska, USA. The mealybug, two other scale insect taxa – one identical to the Tuliptree Scale and the other identical to the Citricola Scale (both Coccidae) – and several distinctive damage types on laurel leaves and probable angiosperm stems document a diverse guild of piercing-and-sucking insects. The find of a phylogenetically early appearing female mealybug implies an early association with a laurel host (Lauraceae). These data provide direct evidence indicating that partitioning of tissues, co-associations, and possible coevolution with a diversity of piercing-and-sucking insects were present early in angiosperm history.