Skip to main content
eScholarship
Open Access Publications from the University of California

Scholarly Works (2 results)

  • Thesis
  • Peer Reviewed
UC Riverside Electronic Theses and Dissertations (2017)

While modern methods have helped to advance our understanding of biodiversity, large gaps in our knowledge remain, particularly with respect to non-model and tropical lineages. My research interests focus on the integration of evolutionary studies with modern methods for study of the biology of the diverse Heteroptera. In my first chapter, I used taxon-specific primers to assay the gut contents of the putatively strictly termitophagous Salyavatinae corroborating that these cryptic tropical predators appear to feed only on members of the family Termitidae. Next, I conducted a comprehensive taxonomic revision of this group of 107 previously described species, describing 15 new species and revising its classification based on a combined morphological and molecular phylogeny of this group and its close relative Sphaeridopinae. In studying the blood-feeding Triatominae, I combed the extensive literature and recorded known sylvatic host associations and added several new sets of observations using PCR on triatomine gut contents with vertebrate specific primers. I assembled and annotated the transcriptomes of 20 species of reduvioid including Triatoma protracta, in an effort to infer the evolutionary forces that acted on proteins which have been heavily modified from their ancestral form in the blood-feeding Triatominae to and aid in hematophagy. I next assessed the microbial associates of a variety of different Triatominae finding that symbiont identity in these insects varies much more widely than has been previously assumed. I also surveyed the microbiomes of two other groups of Heteroptera, Largidae and Miroidea, finding that Largidae reacquire a specific group of Burkholderia symbionts from the environment every generation while the herbivorous members of Miroidea seem to be able to circumvent the nutrient limitations of their plant diet without a symbiotic association with bacteria. These studies illustrate the use of modern molecular methods and archival specimens to understand not just evolutionary history and species diversity of groups of understudied organisms but to infer aspects of their biology such as their biotic interactions with prey or symbiotic bacteria.

  • 3 supplemental videos
  • 5 supplemental files
Cover page: Natural History, Systematics, and Taxonomy of the Termite Assassin Bugs (Reduviidae: Salyavatinae), Host Associations, Salivary Protein Evolution and Bacterial Symbionts of Kissing Bugs (Reduviidae: Triatominae) and Evolutionary Analysis of Microbiota of Miroidea and Largidae
  • Article
  • Peer Reviewed
UC Riverside Previously Published Works (2016)
The insect order Hemiptera, one of the best-studied insect lineages with respect to bacterial symbioses, still contains major branches that lack comprehensive characterization of associated bacterial symbionts. The Pyrrhocoroidea (Largidae [220 species] and Pyrrhocoridae [∼300 species]) is a clade of the hemipteran infraorder Pentatomomorpha. Studies on bacterial symbionts of this group have focused on members of Pyrrhocoridae, but recent examination of species of two genera of Largidae demonstrated divergent symbiotic complexes in these putative sister families. We surveyed the associated bacterial diversity of this group using paired-end Illumina sequencing and targeted Sanger sequencing of bacterial 16S rRNA amplicons of 30 pyrrhocoroid taxa, including 17 species of Largidae, in order to determine bacterial associates and the similarity of associated microbial communities among species. We also used molecular data (4,800 bp in 5 loci, for 57 ingroup and 12 outgroup taxa) to infer a phylogeny of the host superfamily, in order to trace the evolution of symbiotic complexes among Pentatomomorpha species. We undertook multiple lines of investigation (i.e., experimental rearing, fluorescence in situ hybridization microscopy, and phylogenetic and coevolutionary analyses) to elucidate potential transmission routes for largid symbionts. We found a prevalent and specific association of Largidae with Burkholderia strains of the plant-associated beneficial and environmental clade, housed in midgut tubules. As in other distantly related Heteroptera, symbiotic bacteria seem to be acquired from the environment every generation. We review the current understanding of symbiotic complexes within Pentatomomorpha and discuss means to further investigate the evolution and function of these symbioses.

Importance

Obligate symbioses with bacteria are common in insects, particularly Hemiptera, in which various forms of symbiosis occur. However, knowledge regarding symbionts remains incomplete for major hemipteran lineages. Thus, an accurate understanding of how these partnerships evolved and changed over millions of years is not yet achievable. We contribute to our understanding of the evolution of symbiotic complexes in Hemiptera by characterizing bacterial associates of Pyrrhocoroidea, focusing on the family Largidae. Members of Largidae are associated with specific symbiotic Burkholderia strains from a different clade than Burkholderia symbionts in other Burkholderia-associated Hemiptera. Evidence suggests that species of Largidae reacquire specific symbiotic bacteria from the environment every generation, which is a rare strategy for insects, with potentially volatile evolutionary ramifications, but one that must have persisted in Largidae and related lineages since their origin in the Cretaceous Period.
    Cover page: Phylogenetic Evidence for Ancient and Persistent Environmental Symbiont Reacquisition in Largidae (Hemiptera: Heteroptera)
    Top