Host-mediated effects of feeding by winter moth on the survival of Euceraphis betulae

Abstract 1. A potential host‐mediated interaction between the birch‐feeding aphid Euceraphis betulae Koch (Homoptera: Aphididae) and Operophtera brumata L. (Geometridae: Lepidoptera) was investigated, by measuring survival and feeding preference responses of E. betulae to leaves damaged recently by O. brumata larvae. 2. Euceraphis betulae survival was considerably lower on damaged foliage than on undamaged foliage, both in field experiments using cages and on potted saplings in laboratory tests. 3. Euceraphis betulae did not avoid damaged foliage in field experiments although they did avoid damaged foliage in laboratory preference tests using individual leaves. A link between aphid preference and performance on damaged foliage could therefore be demonstrated in the greenhouse/laboratory but not in the field. Multiple factors may influence feeding preference in the more complex field environment. 4. These results suggest that host‐mediated competition may occur between O. brumata and E. betulae , especially in outbreak years when winter moth populations are very high.