Epicuticular wax content in the leaves of cabbage (Brassica oleracea L. var. capitata) as a mechanical barrier against three insect pests

Abstract

Flea beetles (Phyllotreta spp.), cabbage stink bugs (Eurydema ventrale) and onion thrips (Thrips tabaci) cause significant economic problems to cabbage growers in Slovenia. The aim of our study was to assess the potential effect of the epicuticular wax on leaves as defence mechanism against these three cabbage pests. The impact of epicuticular wax content in relation to damage levels of cabbage pests was studied under field conditions at the Experimental Field of the Biotechnical Faculty in Ljubljana on 12 cabbage cultivars (Brassica oleracea L. var. capitata). These insect pests showed weak preference on cabbage heads with high epicuticular wax. There was a strong negative relationship between epicuticular wax content and the level of plants infested (r2 = -0.8399 for flea beetles, r2 = -0.7413 for cabbage stink bugs and r2 = -0.7042 for onion thrips). The cv.'Holandsko pozno rdeče', showed itself to be the most resistant to the cabbage stink bugs and onion thrips, while cv. 'Red Dinasty' was the most resistant against flea beetles.