Protein and transcript abundance in juvenile leaf beetles. (a) Proteins in defensive exudates separated by one-dimensional SDS–PAGE. left: 1 mg secretions of C. populi (C.p.), silver stained, box marks CpopSAO; right: 0.65 mg secretions of P. cochleariae (P.c.), Coomassie stained, box marks PcTo-like. (b) Expression pattern of CpopSAO ±s.d. in different C. populi tissues, n = 3. (c) Expression pattern of PcTo-like ±s.d. in different P. cochleariae tissues, n = 2. Both y-axes are in log10 scale.