Evolution of a Unique Ovipositional Syndrome in the Leafhopper Tribe Proconiini (Hemiptera: Cicadellidae)

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DEB-0089671Christopher H. DietrichDr. Christopher Dietrich of the University of Illinois/Illinois Natural History Survey has been awarded a grant to study aspects of the evolution of reproductive behaviors in insects. This research should help explain the extraordinary success of this group of animals and may suggest improved methods for managing economically important species. Modern phylogenetic methods have greatly improved understanding of evolutionary processes at the level of genes and individual traits, but the processes by which multiple coordinated traits, or adaptive syndromes, evolve remain poorly understood. This project examines the evolution of several morphological, behavioral, and physiological traits related to the unique egg-laying (oviposition) syndrome of proconiine leafhoppers (Insecta: Hemiptera: Cicadellidae). Unlike most leafhoppers, which insert their eggs into plant tissue without coating the egg scars, certain proconiine species coat their egg scars with specialized secretory particles called brochosomes. In most leafhopper species, brochosomes are used primarily to provide a water-repellant coating on external surfaces of the body. In proconiines, brochosomes have assumed a new function in the protection of egg masses. Pregnant female proconiines store brochosomes in globs on their forewings and, after oviposition, scrape them off the wing and onto the egg scar using the hind legs. The brochosomes of ovipositing females differ from those of males and non-ovipositing females and corresponding modifications are found in the legs and forewings. By estimating the phylogenetic relationships among proconiine species using morphological and DNA sequence data, this project will address the question of whether the various traits related to the unique oviposition syndrome were acquired all at once or in a stepwise fashion. The project will provide training for a Ph.D. student and post-doctoral fellow in field sampling, data collection, morphological and molecular genetic methods. The project will also improve collaborative ties between U.S. and Brazilian researchers and will yield improved tools for identifying leafhopper species.