EVIDENCE OF AN AGGREGATION PHEROMONE IN THE FLEA BEETLE, PHYLLOTRETA-CRUCIFERAE (GOEZE) (COLEOPTERA, CHRYSOMELIDAE)

Laboratory olfactometer bioassays and field trapping experiments showed that the flea beetle, Phyllotreta cruciferae (Goeze), was highly attracted by oilseed rape (Brassica napus L.) when flea beetles were on the plant. This attraction was mediated by a flea beetle-produced aggregation pheromone based upon: (1) Oilseed rape damaged mechanically, or by P. cruciferae, or by diamondback moth, Plutella xylostella (L.), did not attract P. cruciferae. (2) Contact with the plants or feeding was required for the production of aggregation pheromone because oilseed rape alone was not attractive when separated from flea beetles by a screen. (3) Equal numbers of males and females were attracted.