Selection response of the Colorado potato beetle for adaptation to the resistant potato, Solanum berthaultii

Thirty cohorts of the Colorado potato beetle (CPB) were reared for ten consecutive generations on the cultivated potato, Solanum tuberosum, and on two accessions (PI 473331 and PI 473334) of the resistant wild species, S. berthaultii. At each generation, selection was imposed for increased survival, decreased development time, and for increased fecundity. Although several parameters responded to selection, net replacement rate (R₀) on S. berthaultii was consistently less than 1/3 that on cultivated potato. At the tenth generation, each S. tuberosum strain female replaced herself with 110 daughters, whereas females from strains reared on PI 473334 and PI 473331 produced an average of 30 and 7 daughters, respectively. Slopes of the R₀ regression lines for populations reared on S. tuberosum and S. berthaultii did not differ from zero, indicating no significant response to selection. Our findings suggest that populations of the Colorado potato beetle may have genetic variability in some performance traits for adaptation to S. berthaultii, but that adaptation is unlikely to occur as rapidly as previously reported. 1994 The Netherlands Entomological Society