Antibiosis effects of 20 potato cultivars to the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Col. Chrysomelidae)

The Colorado potato beetle, Leptinotarsa decemlineata (Say), is a serious pest of potato, Solanum tuberosum L. worldwide. In this study, to determine the probable antibiotic effects of 20 potato cultivars on L. decemlineata, life predestination of neonate larvae were investigated until emergence of adults on studied cultivars. Tubers of different cultivars were planted in pots in a greenhouse. After the emergence of the plants, one sleeve cage was set on each pot and 15 neonate larvae were released and reared. Weight of larvae on 12(th) day after release, developmental time of larvae and pupae and mortalities of these stages were determined as antibiosis indices of the cultivars. Data was analyzed with SAS statistical software and comparison of means was performed with Tukey's HSD procedure in 5% level. It was found that reciprocal effect of cultivar x year was significant for all of the studied indices (P<0.001). The comparison of means showed that the least weight of larvae on 12(th) day after releasing was observed on the Carlita, Delikat and Raja cultivars in 2007 and on the Delikat, Bright and Carlita cultivars in 2008. The highest larval mortalities were observed on Delikat and Carlita cultivars in 2007 and on the Carlita, Sinja and Delikat cultivars in 2008. The longest developmental time in 2007 was observed on the Morene, Romina and Carlita and in 2008 this time was observed on the Carlita, Aparret and Bridjet. With cluster analysis on the basis of mortalities of immature stages and developmental period by using UPGMA procedure based on Euclidean distance, 20 studied cultivars were grouped in 5 distance clusters.