Evaluation of cucumber (Cucumis sativus L.) accessions (cultivars and lines) against the two-spotted spider mite (Tetranychus urticae Koch.) and kanzawa spider mite (T. kanzawai Kishida, Acari: Tetranychidae)

Abstract

Forty three cucumber (Cucumis sativus L.) accessions (cultivars and lines) were tested against the two-spotted spider mite (Tetranychus urticae Koch) and kanzawa spider mite (Tetranychus kanzawai Kishida). The highest number of T. urticae and T. kanzawai eggs /female/ day (5.98, and 6.23 respectively) was recorded on the cucumber genotype Blackish Green while the lowest eggs/female/day (2.95 and 3.31) was recorded on Winter Long Green (WLG) for T. urticae and T. kanzawai respectively. On a scale of 1 to 5, the highest visual damage rating was recorded on Blackish Green (4.75 for T. urticae and 4.78 for T. kanzawai) and the lowest damages rating of 1.50 and 1.70 were recorded on WLG for T. urticae and T. kanzawai respectively. Instead of distinct categories of resistance and/or susceptibility, an array of responses (number of eggs laid/female/ day and damage rating) was recorded on the tested cucumber accessions, suggesting two or more genes with additive effects. Based on our findings, Blackish Green was foud to be a susceptible cultivar and Winter Long Green proved to be a resistant one. These two cultivars could be used as a differential host in further studies. Among the Korean cucumber lines, K-4, K-6, and K-20 where found susceptible while K-1, K-2, K-13, and K-15 exhibited some type of resistance to the two mite species.

Keywords

• cucumber
• spider mites
• damage ratting
• resistance