Relationship between water-soluble carbohydrate composition of cabbage (Brassica oleracea L. var. capitata) and damage levels of onion thrips

The impact of water-soluble carbohydrate composition in relation to damage levels of onion thrips (Thrips tabaci Lindeman), were studied under field conditions at the Experimental Field of the Biotechnical Faculty in Ljubljana on 7 cabbage cultivar (Brassica oleracea L. var. capitata). Onion thrips showed weak preference on cabbage heads with high amount of total carbohydrate, fructose and glucose and higher preference on heads with high concentration of sucrose. While amount of total carbohydrate, fructose and glucose were negatively correlated with damage levels (r = -0.7667; r = -0.6947; r = -0.8263), sucrose amount was not. There was a strong positively relationship between sucrose amount and the level of plants infested (r = +0.7378). The cv.‘Hinova’, which had the highest amount of total carbohydrate, showed itself to be the most resistant to the onion thrips.