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

The sugarbeet root maggot (SBRM), Tetanops myopaeformis Roder, is tbe most important insect pest of sugarbeet in the Red River Valley of Minnesota and North Dakota. During the flood year of 1997, tbe adult emer gence model for tbis pest failed to predict a late, prolonged emergence of adults. Low soil moisture bas previously been reported to prevent SBRM development. It was sus pected, because of the high soil moisture resulting from tbe flood in 1997, tbat an upper thresbold of soil moisture also may exist above whicb SBRM do not successfully com plete development. Developmental trials were conducted in controlled environment cbambers to characterize tbis tbreshold. SBRM had significantly greater pupal mortal ity in soils with greater tban 45% soil moisture by weigbt. Soils ranging from 10% to 30% soil moisture by weight had no significant effect on SBRM pupal development.