Submitted to: American Society of Sugarbeet Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 11/13/2000
Publication Date: N/A
Technical Abstract: Sugarbeet root maggot is a major insect pest of sugarbeet The primary control method has been the use of insecticides to reduce larval populations in sugarbeet fields. The almost exclusive use of organophosphate insecticides (chlorpyrifos and terbufos) is conducive to the development of insecticide resistant root maggot. Possible alternatives to these insecticides include the use of biological control agents and the development of germplasm with host plant resistance. Two resistant germplasm lines, F1015 and F1016, have been developed by ARS. A comparison of hybrid performance with and without chlorpyrifos, four experimental hybrids with F1015 as the pollen parent and no insecticide produced between 133 and 584 pounds recoverable per acre less than the same hybrids with chlorpyrifos applied at planting. In contrast, not applying chlorpyrifos to a commercial hybrid reduced recoverable sugar yield by 1096 pounds. Among the biological agents that have been evaluated for root maggot control, the entomopathogenic fungus Metarhizium appears to have the most promise. Under moderate root maggot infestations (1995-1999), the highest yielding Metarhizium treatment produced 24.8 tons per acre, compared with 24.9 tons per acre from the chlorpyrifos treatment and 22.7 tons when no insecticide was used. Current research with Metarhizium will focus on development of commercially useful application techniques and evaluations in diverse environments.