Aggregation response of T. infestans fifth instar nymphs to the epicuticular lipid extracts of specimens of the same population (same age and instar). The dotted line indicates values expected for a random distribution. At 0.1, 1, and 2 equivalent doses, the response was significantly different from a random distribution. The numbers of replicates were N = 8 (0.1 insect equivalent), N = 18 (1 insect equivalent) and N = 17 (2 insect equivalents). Bars show standard error.