Assassin bugs: evolutionary history of the Reduvioidea, a diverse clade of predatory and hematophagous insects

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Evolutionary research explores processes that have shaped biodiversity. With close to 7,000 species known to science, assassin bugs are one of the largest evolutionary lineages of animals where the majority of species hunt other insects. The factors that have allowed assassin bugs to speciate at this scale are unknown, but specializations on certain prey organisms and transitions into a variety of terrestrial habitats are assumed to have contributed to this phenomenon. These hypotheses have largely remained untested, because comprehensive evolutionary trees are unavailable. Assassin bugs include beneficial species used to control plant pests, pollinator predators, and powerful human disease vectors that transmit the causative agent of Chagas disease. An international team led by researchers at the University of California, Riverside will investigate the evolutionary history of assassin bugs, tying together extensive genetic and morphological data with innovative approaches to gather natural history data. One postdoctoral researcher and one PhD student will be trained, several undergraduate researchers will engage in research and outreach, and two short courses on true bug biodiversity will train students, researchers, and others involved in agricultural and public health related research and monitoring. Existing phylogenies of the assassin bugs or Reduvioidea are inadequate to address many evolutionary questions, the paucity of well-described fossils has made it difficult to establish timelines for events including the transition from predatory to blood-feeding life styles, and the classification of Reduvioidea is in disarray. This project will: 1) test phylogenetic hypotheses with emphasis on the poorly resolved Higher Reduviidae and contentious relationships of the hematophagous Chagas disease vectors Triatominae, while maximizing taxonomic coverage and integrating transcriptomic, anchored hybrid enrichment, traditional molecular, and morphological datasets; 2) describe and redescribe fossil reduvioids to bridge taxonomic and geological gaps in the fossil record and test hypotheses on the timing of key biological events; 3) apply metabarcoding approaches to assassin bug gut contents to complement available prey data; 4) study diversification across Reduvioidea, focusing on hypotheses of diversification rate shifts and correlated key innovations, and morphological, physiological, and ecological traits involved in the transition between predation and blood-feeding; 5) use the phylogenetic information generated during this project to propose a new classification of Reduvioidea.