Distinctive leaf feeding patterns on oilseed rapes and related Brassicaceae by flea beetles, Phyllotreta cruciferae (Goeze) (Coleoptera: Chrysomelidae)

Abstract

Two distinctive leaf feeding patterns, termed "edge" and "random", by flea beetles, Phyllotreta cruciferae (Goeze) were identified in 38 Brassicaceae belonging to nine groups of known genomic composition. Edge feeding occurred in the monogenomic diploid Brassica oleracea group (cc genome) and the digenomic amphidiploid B. napus group (aacc genome). All other genomic groups were fed upon randomly. Experimental manipulation of the plant (by leaf edge removal and new edge creation) and the insect (by antennectomy) and paired feeding tests with plants selected for type of feeding pattern revealed some of the salient features of pattern feeding by P. cruciferae. Leaf edge feeding was correlated with a feeding rate one-tenth of that observed for random feeding, suggesting that edge feeding may be determined by physical and/or chemical factors that render the leaf unpalatable or difficult to feed upon or both.Key words: Insecta, Phyllotreta cruciferae, Brassicaceae, feeding pattern, feeding rate