Tomato cultivar susceptibility to Egyptian cotton leafworm (Lepidoptera: Noctuidae) and Colorado potato beetle (Coleoptera: Chrysomelidae).

摘要

Commercial tomato (Lycopersicon esculentum) cv. Marmand, Edkawy, VF-145, GS-27, Pakmor-B, Floradade and UCX-281 grown under greenhouse conditions were evaluated for differences in mortality and feeding (leaf area ingested) of fourth-instar larvae ofSpodoptera littoralis and Leptinotarsa decemlineata. Floradade, GS-27, and Packmor-B plants sustained the most damage (more leaf area ingested) by S. littoralis while GS-27 and VF-145 sustained the most damage by L. decemlineata. Mortality of L. decemlineata was lowest on the F1 hybrid GS-27, indicating that GS-27 was the most susceptible cultivar to the pest. Variation in chemical and nutrient composition (reducing sugars, total sugars, ascorbic acid, total phenols and total protein content) of leavesexplained some of the observed differences in mortality and feeding among the tomato cultivars and insect species. The correlation coefficient of reducing sugars with leaf consumption was positive (0.758) for S. littoralis and negative (-0.485) for L. decemlineata. The correlation coefficients of ascorbic acid with insect mortality were negative (-0.389 for S. littoralis and -0.459 for L. decemlineata) indicating that they may require ascorbic acid for growth. Total phenols in tomato leaflets were positively correlated with mortality of S. littoralis. Edkawy, VF-145, and UCX-281 were the most resistant cultivars.