High soil moisture effects on pupation of sugarbeet root maggot, Tetanops myopaeformis (Roder) (Diptera: Otitidae).

The sugarbeet root maggot (SBRM), Tetanops myopaeformis Roder, is the most important insect pest of sugarbeet in the Red River Valley of Minnesota and North Dakota. During the flood year of 1997, the adult emergence model for this pest failed to predict a late, prolonged emergence of adults. Low soil moisture has previously been reported to prevent SBRM development. It was suspected, because of the high soil moisture resulting from the flood in 1997, that an upper threshold of soil moisture also may exist above which SBRM do not successfully complete development. Developmental trials were conducted in controlled environment chambers to characterize this threshold. SBRM had significantly greater pupal mortality in soils with greater than 45% soil moisture by weight. Soils ranging from 10% to 30% soil moisture by weight had no significant effect on SBRM pupal development.