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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)


Plant Science

First Advisor

Paul J. Johnson


Native and introduced grass species, excluding grain crops, are an essential part of ecosystems in North America and recently have been a focus of research for biomass production for bioenergy (e.g. big bluestem, giant miscanthus, prairie cordgrass, switchgrass), historically few insect species on these grasses have been reported to have pest characteristics, however most insect associates still remain unknown or unstudied. Many of the characteristic and conspicuous grass species have host specific gall midges (Diptera: Cecidomyiidae). Grass feeding gall midges investigated feed on inflorescence structures ovules and immature caryopses, thus decreasing the reproductive success of their hosts. Native gall midges, i.e. Chilophaga virgati Gagné, and Stenodiplosis spartinae Gagné, have demonstrated impacts as pests on grasses grown for seed and cellulosic ethanol. The introduced S. bromicola Marikovskiy & Agafonova and S. geniculati Reuter reduce seed production and may provide previously unrecognized biological control activity on their invasive host grasses. Adult gall midges and parasitoids were field collected on host plants. Inflorescences and florets were sampled during 2014 and 2015, and adult gall midges and parasitoids reared for identification, confirmation of host associations, and life history compilations. Gall midge species-specific intraguild competition by parasitoids was found, revealing endoviii and ectoparasitoids affecting population dynamics and their subsequent impact on economic value of their host grasses.

Library of Congress Subject Headings

Gall midges--South Dakota
Parasitoids--Hosts--South Dakota
Grasses--South Dakota


Includes bibliographical references (pages 33-38)



Number of Pages



South Dakota State University


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