Sugarbeet Root Maggot Resistance of Hybrids with a Maggot Resistant Pollinator

Sugarheet root maggot (Tetanops inyopaeforinis) is a major insect pest of sugarheet (Beta vulgaris) throughout much of North America. Host plant resistance is a potential alternative to the few chemical insecticides currently being used to control the root maggot. Gerniplasm lines with root maggot resistance have been identified but only minimal information about the resistance of hybrids created by crossing these lines with a susceptible ems parental line is available. This study compared the performance of four hybrids with a maggot resistant pollinator. F1015, and a susceptible commercial hybrid, with and without insecticide. With insecticide, the yield of the susceptible commercial hybrid was 7.8 Mg ha' greater than the root yield without insecticide. In contrast, the average root yield increase attributable to the application of insecticide for the four hybrids with F1015 as the pollinator was only 0.8 Mg ha* With insecticide, the root yield of the susceptible hybrid was equal to or greater than the root yield of the four resistant hybrids with insecticide; however, without insecticide, the yield of the susceptible hybrid was significantly lower than all the hybrids except one that also had a relatively low yield when insecticide was applied. These root yield and similar sucrose yield patterns indicated that when F1015 was used as a pollinator the resulting hybrid would have substantial root maggot resistance. The results