TITLE:
Bluestem Gall Midge Annual Production Cycle and Effects on Grass Seed Production
AUTHORS:
Earle S. Raun, Robert B. Mitchell
KEYWORDS:
Life History, Seed Midge, Seed Predation, Stenodiplosis wattsii
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.9 No.10,
September
28,
2018
ABSTRACT: The
bluestem gall midge (Stenodiplosis
wattsii Gagné)
is native to the grasslands of North America. It feeds on the developing 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 in the USA. 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 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. Additionally, the warm-season prairie grasses were surveyed
in nine other counties in Nebraska and the bluestem gall midge was found in
each species surveyed from all nine counties. 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.