STRUCTURE AND FUNCTION OF ANTENNAL LOBE NEURONS IN THE MALE TURNIP MOTH, AGROTIS-SEGETUM (LEPIDOPTERA, NOCTUIDAE)

Interneurons with dendritic branches in the antennal lobe of the male turnip moth, Agrotis segetum (Schiff., Lepidoptera: Noctuidae), were i nvestigated with intracellular recording and staining methods. Sevente en projection neurons that transmit information from the antennal lobe to higher centers in the brain displayed dendritic arbors in the male specific macroglomerular complex (MCC) and responded to chemical comp onents of the female sex pheromone used in species-specific sexual com munication. Most of the projection neurons responded to several of the pheromone components tested, and a precise correlation between the lo cation of the dendritic arborization and the physiological response co uld not be demonstrated. One MGC-projection neuron fit the definition of ''blend specialist''. It did not respond to the individual componen ts of the behaviorally active pheromone blend, but showed a strong res ponse to the components when combined in the species-specific blend. S ome of the projection neurons also showed clear responses to phenylace taldehyde, a flower-produced compound and/or to (E)-2-hexenal, a commo n green-leaf volatile. In eight neurons, the axonal projection could b e followed to the calyces of the mushroom body, and subsequently to th e inferior lateral protocerebrum. Four local interneurons were charact erized both morphologically and physiologically. Each neuron arborized extensively throughout the antennal lobe, and each responded to one o r several of the pheromone compounds, and/or to one or both of the pla nt-produced compounds. One of the local interneurons responded exclusi vely to the pheromone blend, but not to the individual components,