Aggregation response (mean ± S.E.) of T. infestans fifth instar nymphs to 1 equivalent of the epicuticular lipid fractions of specimens of same age and instar. DG: diacylglycerols, TG: triacylglycerols, W: waxes, FA: fatty alcohols, HC: hydrocarbons, FFA: free fatty acids. Asterisk indicates statistical significance. The number of replicates was N = 6, except for DG and TG (N = 7).