OLEFINIC ACETATES, DELTA-9, 11-14-OAC AND DELTA-7,9-12-OAC USED AS SEX-PHEROMONE COMPONENTS IN 3 GEOMETRID MOTHS, IDAEA-AVERSATA, IDAEA-STRAMINATA, AND IDAEA-BISELATA (GEOMETRIDAE, LEPIDOPTERA)

Pheromone compounds so far identified from most geometrid moths consis t of all-Z diene, triene, or tetraene hydrocarbons with chain lengths of C-17 to C-21, and their monoepoxide derivatives biosynthesized from linoleic and linolenic acids. The present study reports the occurrenc e of olefinic acetates as sex pheromones in three species of Geometrid ae. (Z,Z)-9,11-tetradecadienyl acetate and (Z,Z)-7,9-dodecadienyl acet ate found in female gland extracts of Idaea aversata elicited signific ant responses from conspecific male antennae in gas chromatography wit h electroantennographic detection (GC-EAD). In extracts of I. stramina ta, (Z,E)-7,9-dodecadienyl acetate, (E,Z)-7,9-dodecadienyl acetate, an d (Z,Z)-7,9-dodecadienyl acetate were found, and the synthetic compoun ds elicited strong responses from conspecific male antennae. In the th ird species, I. biselata, only (Z,Z)-7,9-dodecadienyl acetate was foun d in the female extracts, and this compound elicited a strong EAD resp onse from the conspecific male antenna. The identities of the pheromon e components in I. aversata and I. straminata were further confirmed a ccording to their characteristic ions after GC-MS analyses. Single sen sillum recordings from I. aversata showed two types of pheromone-detec ting sensilla present on the male antenna. One type contained two rece ptor neurons, one of which was specifically tuned to (Z,Z)-9,11-tetrad ecadienyl acetate, the other to (Z,E)-9,11-tetradecadienyl acetate. A second type contained one neuron responding to (Z,Z)-7,9-dodecadienyl acetate. The two types were clearly different also with respect to ext ernal morphology, the former being considerably longer and having a la rger base diameter. Also in I. straminata two physiological types of s ensilla could be distinguished. One type contained two neurons, one of which responded to (Z,Z)-7,9-dodecadienyl acetate, the other to (Z,E) -9,11-tetradecadienyl acetate. The second type contained one neuron, r esponding to (Z,Z)-7,9-dodecadienyl acetate. No correlation between ex ternal morphology and physiological response of the investigated sensi lla was observed in I. straminata. In field tests, a two-component ble nd containing (Z,Z)-9,11-tetradecadienyl acetate and (Z,Z)-7,9-dodecad ienyl acetate in a ratio of 10:1 was attractive to males of I. aversat a. This two-component blend was also attractive to males of I. stramin ata, but in a ratio of 1:1. High numbers of male I. biselata were caug ht in traps baited with (Z,Z)-7,9-dodecadienyl acetate alone. The inco rporation of deuterium labels into pheromone components after topical application of deuterium-labeled palmitic acid confirmed that the pher omone components of I. aversata could be synthesized from this precurs or, as has been previously observed for acetate pheromone components o f many other moth species. Our results suggest that an evolutionary re versal back to the production of palmitic acid-derived pheromone compo nents has occurred within the geometrid subfamily Sterrhinae.