Use of a detached leaf screening method for segregating Colorado potato beetle (Leptinotarsa decemlineata Say) resistant Solanum hybrid lines

A diploid segregating population for resistance to Colorado potato beetle (CPB) was developed by crossing the resistant Mexican species Solanum pinnatisectum (S. pnt., 2n = 2x = 24) with the susceptible S. cardiophyllum (S. cph., 2n = 2x = 24). A resistant hybrid plant from this cross was selected and backcrossed as a female to S. cph in order to generate a backcross family. A beetle feeding preference test bioassay was developed to examine segregation for CPB resistance in 345 backcross progeny. A screening method that optimized the length of the feeding period allowed the quantification of CPB resistance in the backcross progeny. Percent resistance of the test lines over the susceptible control was determined using the formula R = 100 × [C/(C + L)]