The titres of lectins in the haemolymph of Lacanobia oleracea and the effects of parasitism by the ectoparasitoid wasp Eulophus penicornis

Serum from larvae of Lacanobia oleracea L. (Lepidoptera; Noctuidae) parasit ized by Eulophus pennicornis (Hymenoptera; Eulophidae) and from normal non- parasitized lan ae is capable of agglutinating rabbit, sheep, calf, goat, c hicken, horse and human erythrocytes, but not yeast. Studies with a range o f inhibitory carbohydrates showed that serum lectins(s) had specificity for sugars containing galactose and for rhamnose. and for the glycosubstances fetuin and asialofetuin. Lectin activity is heat-labile and is not dependen t on calcium. Parasitism by E. pennicornis caused an increase in the agglut ination titre of the serum from larvae of L. oleracea but not an increase i n specific activity (titre per mg protein per ml). However, when venom from the venom gland of female wasps was injected into L. oleracea larvae, both the agglutinating activity and the specific activity of the larval serum i ncreased. The possible causes of this increase are discussed. It is suggest ed that venom contains antigenic components which, when injected into the h aemocoel of the L. oleracea larva, may be increasing lectin synthesis and/o r release into the serum.