MEASURING RESISTANCE TO THE COLORADO POTATO BEETLE (COLEOPTERA: CHRYSOMELIDAE) IN POTATO

A sensitive test was sought that could be used to detect small differences in resistance to the Colorado potato beetle (CPB) in Solanum species. Three tests were evaluated and compared. One test compared adult CPB foliage consumption of leaf disks from a susceptible potato cv, S. tuberosum, with disks from two S. chacoense clones. The second test compared weight gain on foliage from the three plants by 4th instar larvae and the third test compared larval development rate and mortality. With sufficient replication all three of the tests could detect significant differences between each of the test clones. The most sensitive test measured the stage of development of neonate larvae after feeding on test plants four days. This test required only four replicates to detect a 50% difference from the overall mean assuming an alpha level of 0.05 and a beta level of 0.10.