Comparative tissue specific transcriptomes of Homalodisca vitripennis and Entylia carinata

We used RNA-Seq to test hypotheses for the origins of morphological novelty. Treehoppers (Hemiptera: Membracidae) are sap-sucking insects that fascinate naturalists due to their elaborate helmet, an enlarged projection of the 1st thoracic segment dorsal bodywall (the pronotum) that has been molded by natural selection into an array of structures aiding crypsis, mimicry, and/or aposematism. Members of their sister group, the leafhoppers (Cicadellidae), exhibit the plesiomorphic condition, having a flat, collar-like or shield-like pronotum. In recent literature morphologists and developmental biologists have held differing views of the developmental origin of the treehopper helmet. Evidence from gene expression in treehoppers, and RNA interference in other insects, suggest that co-option of genes in the wing patterning network may be involved, while evidence from anatomically similar beetle horns suggest the possibility of leg-patterning gene co-option. We tested these and other hypotheses with comparative transcriptomics to analyze gene expression in eight body regions of nymphal Entylia carinata (a treehopper) and Homalodisca vitripennis (a leafhopper).