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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Publications at this Location » Publication #210380
Title: Bluestem gall midge annual production cycle and effects on grass seed production

Author
item RAUN, EARLE - PEST MANAGEMENT CO.
item Mitchell, Robert - Rob

Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2018
Publication Date: 9/28/2018
Citation: Raun, E.S., Mitchell, R. 2018. Bluestem gall midge annual production cycle and effects on grass seed production. American Journal of Plant Sciences. 9(10):2077-2085. https://doi.org/10.4236/ajps.2018.910151.
DOI: https://doi.org/10.4236/ajps.2018.910151

Interpretive Summary: The bluestem gall midge is an insect native to the grasslands of North America. It feeds on the developing seeds of warm-season grasses and reduces seed production, but little is known about the insect. We investigated the presence of the bluestem gall midge in big bluestem, sand bluestem, little bluestem, and indiangrass commercial seed production fields in 2001, 2002, 2003, and 2004. Our objectives were to determine the annual production cycle of the bluestem gall midge, the range of the infestation in Nebraska, and estimate its impact on seed production. The midge goes through four generations per year and overwinters in seeds and emerges in mid-June of the following year. The bluestem gall midge was found in five species of warm-season prairie grasses from nine counties in Nebraska, and likely occurs in most places where these grass species exist. The bluestem gall midge damaged a large number of seed from each species, and reduced average seed production by 54% in eastern Nebraska. This study is the first to document the negative effects of the bluestem gall midge on the production of viable seed in sand bluestem and indiangrass.

Technical Abstract: The bluestem gall midge (Stenodiplosis wattsii Gagné) is native to the grasslands of North America. It feeds on the developing caryopses (hereafter referred to as seeds) of warm-season grasses during a portion of its lifecycle, but little is known of the biology and extent of gall midge infestations in native warm-season grasses. We investigated the infestations of the bluestem gall midge in big bluestem (Andropogon gerardii Vitman), sand bluestem (Andropogon gerardii var paucipilus), little bluestem [Schizachyrium scoparium (Michx.) Nash], and indiangrass [Sorghastrum nutans (L.) Nash] commercial seed production fields during 2001 through 2004. Our objectives were to determine the annual production cycle of the bluestem gall midge, the range of the infestation in Nebraska, and estimate its impact on seed production. In eastern Nebraska, the midge goes through four generations with the fourth entering a larval diapause, overwintering in seeds and emerging in mid-June of the following year. The bluestem gall midge was found in warm-season prairie grasses from nine counties in Nebraska. The bluestem gall midge damaged from 31% of the little bluestem seed to 67% of the big bluestem seed, and, on average, reduced the production of viable seed by 54% across the four grass species in eastern Nebraska. This study is the first to document the negative effects of the bluestem gall midge on the production of viable seed in sand bluestem and indiangrass.