Exploring Megaspilidae (Hymenoptera: Ceraphronoidea) Through Morphology and More
Open Access
- Author:
- Trietsch, Carolyn
- Graduate Program:
- Entomology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 21, 2019
- Committee Members:
- Andrew Robert Deans, Dissertation Advisor/Co-Advisor
John Frazier Tooker, Committee Chair/Co-Chair
Istvan Miko, Committee Member
Heather M Hines, Committee Member
Benoit A Dayrat, Outside Member - Keywords:
- Ceraphronoidea
Megaspilidae
Ceraphronidae
Conostigmus
Dendrocerus
Megaspilius
Hymenoptera
Wasp
Taxonomy
Systematics
Morphology
Histology
Parasitoid
Insect
Entomology
Natural History - Abstract:
- Ceraphronoidea (Insecta: Hymenoptera) is a small but widespread superfamily of parasitoid wasps found on every continent except Antarctica. Ceraphronoids are some of the most commonly collected wasps in the world and include species that are important for agriculture, yet little is known about their life histories or even how many species there are. With habitat loss and extinction rates rising, it is crucial for taxonomists to describe and document these species before they are lost forever. My dissertation aims to accomplish this by providing a systematic exploration of the ceraphronoid family Megaspilidae, with a central focus on the genus Conostigmus Dahlbom in North America, North of Mexico. The first chapter introduces audiences to Ceraphronoidea, and the second and third chapters focus on describing and documenting the biodiversity of individual species of Megaspilidae. I redescribe Conostigmus albovarius Dodd, a unique species of Conostigmus with metallic coloration that was previously only known from a single female specimen. I report more female specimens and describe the male of the species for the first time, providing images of both male and female specimens so that others can easily identify them. I also describe a new species from Costa Rica, Dendrocerus scutellaris Trietsch and Mikό, characterized by a series of spines that could be used for sawing its way out of the host insects it parasitizes. This species is the only ceraphronoid known to have these structures, and it serves as an example of how morphology can be used to hypothesize life history traits. The morphological descriptions of both Conostigmus albovarius and Dendrocerus scutellaris are provided in semantic format for ease of data integration and computerized searches among datasets. The fourth chapter explores morphological structures shared by all Ceraphronoidea: pairs of translucent cuticle present on the dorsal and ventral surfaces of the metasoma, with the ventral translucent patches flanked by rows of bristles. By using a variety of histological techniques, I show that the patches of bristles are associated with glandular activity, whereas the patches of translucent cuticle could be associated with endocrine glands or extraocular photoreceptors. These structures have never been studied before, despite the fact that they are found in other types of wasps as well and could offer clues to how these distant are related and how they may have evolved. The fifth chapter is a photographic catalog of historical Ceraphronoidea specimens present in the collections of the Museum national d'Histoire naturelle (MNHN) in Paris, France. The majority of these specimens have never been imaged or illustrated before, impeding taxonomic work and identification efforts. I also report unpublished species notes from former Ceraphronoidea taxonomist Paul Dessart, as well as the discovery of the missing male holotype of Ceraphron testaceus (Risbec, 1953) (Hymenoptera: Ceraphronidae) and several potential types of Aphanogmus aphidi (Risbec, 1955) (Hymenoptera: Ceraphronidae). This chapter will serve as a valuable resource to help taxonomists and others identify and research these species in the future. The sixth chapter revises all Conostigmus species found in the Nearctic, which I define as North America, north of Mexico. I examine and redescribe 10 of the 32 species that were previously known from the Nearctic; the remaining 22 species remain uncertain due to limited, damaged or missing type material. I describe 12 new species and report the occurrence of two additional species that were previously thought only to exist in outside of the Nearctic. I also provide an annotated key for the identification of Nearctic Conostigmus species, complete with images of all species and their distinguishing characteristics. This work represents the first in-depth study and revision of Conostigmus species in the Nearctic. The seventh chapter takes a step back to explore a larger topic impacting all entomologists: the ethics of insect collecting. I provide the Insect Collector’s Code as a guide to ethical insect collecting for students and those training to become entomologists. In sharing this code with others, I hope to facilitate awareness and discussion of the ethics of insect collecting, and promote ethical and responsible collecting practices in the field of entomology. The appendices contain my contributions to other taxonomic work, including a revision of Malagasy species of Conostigmus and a description of a new species of Conostigmus fossilized in Eocene Baltic amber. I include a tribute to former Ceraphronoidea taxonomist Paul Dessart and discuss details of his life. Finally, I explore the lives of Penn State graduate students and discuss how, after tragically losing a fellow student, we started a craft-based social night to cope with the pressures of graduate school and build a supportive community. This work takes several steps forward in documenting the biodiversity of Ceraphronoidea and understanding the morphology and evolutionary relationships of the superfamily. As well as representing important taxonomic contributions to Hymenoptera research, this work also extends beyond the field of taxonomy to explore the ethics of insect collecting within the field of entomology, as well as looking into the lives of the scientists behind the science.