CENTRAL NERVOUS PROCESSING OF SEX-PHEROMONES IN 2 STRAINS OF THE EUROPEAN CORN-BORER OSTRINIA-NUBILALIS (LEPIDOPTERA, PYRALIDAE)

Antennal lobe neurones were investigated in the pyralid moth Ostrinia nubilalis using intracellular recording and staining techniques. Respo nse characteristics of antennal lobe neurones from males in the so-cal led E and Z strains, in Fl hybrids and in parental backcrosses were st udied. The antennal lobe of a male O. nubilalis comprises approximatel y 30 ordinary glomeruli and three enlarged glomeruli making up the mac roglomerular complex (MGC). Receptor neurones enter the antennal lobe via the antennal nerve and arborize in single glomeruli. Intracellular ly stained, pheromone-responding projection neurones in both parental strains arborized in different glomeruli within the MGC, irrespective of their response characteristics. Neurones were grouped according to their specificity to single pheromone components and to pheromone blen ds. Component-specific, blend-specific and generalist neurones were fo und. Specificity only occurred at low stimulus concentrations and disa ppeared as concentrations increased. Although all neuronal types were present in both pheromone strains and crossings, differences in abunda nce and sensitivity were found. In the parental strains, neurones resp onding to the major pheromone component and to the respective strain-s pecific blend were more abundant than neurones responding to the minor component and the blend produced by the other strain. Neurones invest igated in ZxE hybrids responded similarly to those of E-strain males, whereas neurones in EZxZ paternal backcrosses responded similarly to t hose of Z males. In the hybrids and paternal backcrosses, hybrid-blend -specific neurones were present that were not found in parental-strain males.