Abstract
Cross-reaction tests with cornicle droplets as the pheromone source were conducted using the five species: Aulacorthum solani Kaltenbach, Myzus persicae Sulzer, Macrosiphum euphorbiae Thomas, Aphis rumicis Linné, Aphis craccivora Koch. The degree of response was estimated using the index of dispersion of the clusters, which were mainly composed of adults apterous virginopara or old nymphs. A. solani and A. craccivora were highly responsive to the cornicle droplets from the other species.
M. persicae was little responsive to the droplets from the other species, and the degree of response to droplets from the same species was low. The cornicle secretion of M. persicae elicited excellent alarm response from the other aphid species, but the cornicle secretion from the other species responded differently to each species. Other observations in these tests include: A. solani began to respond at a constant 10-15 sec following exposure to cornicle droplets from the conspecies, and responded violently at 35-45 sec after exposure. The interval until response of A. solani to the secretion from other species varied, being 10-15 sec for M. euphorbiae and 4-5 sec for M. persicae.
