Abstract: 【Aim】 To characterize the function and morphology of major pheromone tuned olfactory receptor neurons and their central projection to the brain in the cotton bollworm, Helicoverpa armigera. 【Methods】 Single sensillum recording was used to record the response of major pheromone tuned olfactory receptor neurons to sex pheromones, and staining with a fluorescent dye used to label the neurons. Immunohistochemistry was used to label the antennal lobe glomeruli. Laser scanning confocal microscope was used to acquire the images of antennal lobes with stained neurons, and the image software ZEN and Amira 4.1.1 was used to analyze the data. 【Results】 Obvious electrophysiological responses of trichoidea sensilla on the antennae of male adults of H. armigera to the major pheromone component Z11-16∶Ald were recorded, and the olfactory receptor neurons housed in the sensilla were successfully labeled by staining. Two olfactory receptor neurons were observed in Z11-16∶Ald-responsive sensllium. The axons of these two olfactory receptor neurons project via the antennal nerve to the cumulus and an ordinary glomerulus in the antennal lobe, respectively. 【Conclusion】 The combination of single sensillum recording and staining with the fluorescent dye can be applied in the identification of the function and morphology of olfactory receptor neurons housed in the antennal sensilla of insects and their central projection pathway to the antennal lobe glomeruli. Compared with the cobalt-lysine, the staining with fluorescent dye is more practical and facilitates the image acquisition and three-dimensional reconstruction. Such method provides technical support for the investigation on the projection pathway of other olfactory receptor neurons of H. armigera to determine the relationship between the peripheral odor receptor perception and the central nervous system.

Key words: Helicoverpa armigera, olfactory receptor neuron, glomerulus, antennal lobe; single sensillum recording and staining