Lanternflies (order Hemiptera, family Fulgoridae) and their closest planthopper relatives (family Dictyopharidae) constitute a strikingly diverse and exceedingly charismatic insect group, with some iconic species (such as the “peanut-headed bug” pictured below) ubiquitously used to exemplify tropical insect biodiversity and bizarre insect evolution. Together, these insect families include more than 1,000 described species that are distributed around the world, with the highest diversity occurring in the tropics. These insects are exclusively sap-feeding herbivores, and can cause damage to their host-plants. Additionally, the insects harbor within their digestive system multiple species of bacteria that provide to the insects essential nutrients that are not available in the insects’ plant-sap diet.
Despite the many interesting aspects of these insects, their evolutionary history is virtually unknown. The goal of this project is to reconstruct the evolutionary relationships within this group and to explore co-evolutionary trends between the insects and their bacterial endosymbionts. Analyses will be based on data integrating modern DNA sequencing technology and traditional comparative morphology. Products of this research will include not only the phylogenetic trees of the insects and their endosymbiotic bacteria, but also new internet-accessible tools to aid in the taxonomic identification of included species.
This research will provide an evolutionary framework for integrating other scientific studies conducted on the biology and ecology of individual planthopper species. The identification tools to be developed will be of considerable value to scientists studying these insects. Additionally, the cutting-edge evolutionary analyses carried out through this research will serve as a model for similar studies on other plant and animal groups. This project will provide training for several students at various academic levels, adding to the next generation of experts in systematic entomology.
Research Objectives, Goals, and Products:
This proposal integrates 4 major objectives into a large-scale phylogenetic investigation:
- Objective 1. Using Large-Scale Phylogenetic Reconstruction to Test and Revise the Classification of Fulgoridae and Dictyopharidae: This project design calls for the assembly of a combined-data matrix for phylogenetic inference, to include DNA nucleotide sequence data from 7 loci and coded morphological characters of adults (including external and genitalic features). Data will be generated from a taxonomic sample of 450 species representing 200 genera. The taxonomic sampling strategy is to maximize representation of all major described lineages (subfamilies, tribes, and genera), while allowing for the inclusion of multiple exemplar species per genus, when available; thus, any phylogeny-based revisions to the classification proposed will focus on higher rankings (subfamilies and tribes).
- Objective 2. Testing Hypotheses of Co-Diversification between Planthoppers and Endosymbionts: This project design calls for generation of DNA sequence data from 2 loci (16S rDNA and 23S rDNA) for each of 3 endosymbiotic bacterial species housed within the 450 Fulgoridae and Dictyopharidae specimens to be included in the phylogenetic analysis described in Objective 1 (above). These sequence data will allow us to detect and distinguish among the various bacterial endosymbionts present, and phylogenetic reconstructions of these endosymbiont lineages will allow us to test for codiversification between endosymbionts and their planthopper hosts (using the phylogenetic reconstruction of Fulgoridae + Dictyopharidae from Objective 1), and to estimate the age of the origins of these endosymbiont associations. We will use in-situ hybridization to obtain images of endosymbionts and to test for localization of endosymbionts to a bacteriome (characteristic of an ancient obligate association).
- Objective 3. Hypothesis Testing: Origins & Dispersal, Morphological Character Evolution:
The phylogenies of Fulgoridae, Dictyopharidae, and their endosymbiotic bacteria resulting from completion of Objectives 1 and 2 (above) will be used to evaluate evolutionary hypotheses concerning planthopper origins and subsequent biogeographic dispersal and morphological character evolution:
- A. Origins and Biogeographic Dispersal: The global distribution of extant Fulgoridae is distinctly different from that of Dictyopharidae; divergence date analysis of the phylogenies of both families, under ML with the software program r8s and Bayesian methods in BEAST will allow us to examine the chronologic and geographic origins of each family and compare alternative hypotheses of intercontinental dispersal between the two.
- B. Morphological Character Evolution. Fulgoridae are most renowned for their unusually elongate and ornamented head processes, as well as for their wax production, which in some species coats body segments and/or wings, and in others forms elaborate abdominal plumes that can equal or exceed the length of the insect. Many dictyopharid species do have elongate (although typically not ornate) head processes, but Dictyopharidae are not known to produce such cuticular wax. Characters associated with head process morphology, cuticular wax production, and other coded characters (e.g., pigmentation of the body, forewings, hindwings, host-plant associations, presence of as yet unidentified endosymbionts, etc.) will be mapped on resulting phylogenies to evaluate alternative hypotheses regarding the evolution of such features within the Fulgoridae + Dictyopharidae lineage. These characters will be investigated individually and as correlated character states, since we anticipate that multiple character systems may reflect similar adaptive utility (e.g., the hypotheses that head processes and/or male wax plume production are implicated in sexual selection), or may correlate with the presence of certain bacterial endosymbionts (e.g., the hypothesis that certain secondary bacterial endosymbionts of Fulgoridae, but not Dictyopharidae, are involved in cuticular wax production).
- Objective 4. Production of Website with Interactive Identification Keys: A website will be developed to disseminate research results and other relevant biological and systematic information; for example, the website will include an updated checklist of genera of Fulgoridae and Dictyopharidae – information not currently available in a single source – and geographic distributions of each included genus. This website will incorporate, as a central feature, interactive identification keys to major lineages within Fulgoridae and Dictyopharidae. Identification keys for most genera of Fulgoridae and Dictyopharidae do not exist; those that do are incomplete and difficult to obtain. Using LucID3 ver.3.4, an online, interactive identification key will be produced for world genera of Fulgoridae and Dictyopharidae, based on examination of type specimens from the major world collections and on the new phylogeny and classification developed through completion of Objective 1 (above). This key will be richly photo-documented with high-quality Automontage images of collected fulgorid specimens and taxonomically important characters. A dichotomous key for printed publication will be generated from the same data using LucID3.