Chemical Releasers of Social Behavior. VII. The Isolation of 2-Heptanone from Conomyrma pyramica (Hymenoptera: Formicidae: Dolichoderinae) and Its Modus Operandi as a Releaser of Alarm and Digging Behavior1

Abstract

The anal glands of Conomyrma pyramica (Roger) produce 2-heptanone. This alkanone is a strong releaser of alarm in this dolichoderine species. Typical alarm behavior is produced also by homologous 2-alkanones with a chain length of 6–9 carbon atoms. Movement of the carbonyl group toward the center of the heptanone chain causes only a slight diminution in alarm-releasing activity. 2-Heptanone is a powerful attractant for workers of C. pyramica at both low and high concentrations and can attract workers over distances exceeding 6 ft. Ants respond to this ketone with a peculiar lurching behavior which is particularly evident as workers approach the ketonic source. Workers are repelled when they approach centers of high ketone concentration and they will not enter their nest when a high concentration of 2-heptanone is applied to the nest opening. On the other hand, the introduction of lower concentrations of 2-heptanone into the nest can release escape behavior in workers of C. pyramica. In addition, this alkanone releases strong digging behavior in workers. The possibility that this alarm pheromone may function also in a defensive capacity and the suitability of fairly short-chain aliphatic ketones as releasers of alarm are discussed.