The physiological action of pheromone biosynthesis activating neuropeptide (PBAN) on isolated pheromone glands of Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) was investigated with regard to the role of the Ca2 channel in stimulating pheromone biosynthesis. A dose–response profile indicated that the minimum level of PBAN stimulation was achieved at 10−11 M. PBAN activity requires the influx of extracellular Ca2 . A time delay of up to 7.5 min from receptor activation by PBAN and influx of extracellular Ca2 was determined. These results indicate that activation of the PBAN-receptor maintains the activation of a Ca2 channel for a period of time. Similar results were found using transfected Sf9 cells expressing the cloned PBAN-receptor. This indicates that the Sf9 cells have a Ca2 channel that is coupled to the receptor in a similar way as in the pheromone gland cells. To determine the type of Ca2 channel, isolated glands were incubated with PBAN and organic Ca2 channel blockers. L-type voltage-gated Ca2 or nonselective Ca2 channel blockers did not inhibit pheromone production. However, quinidine, a potassium channel blocker, inhibited pheromone production. These results indicate that the receptor-activated Ca2 channel in the pheromone gland may not be a voltage-activated Ca2 channel but rather a nonselective ion channel. Our results provide further insight into the action of PBAN with regard to the Ca2 channel in the signal transduction of pheromone biosynthesis in moths.
Annals of the Entomological Society of America
Vol. 99 • No. 5
Vol. 99 • No. 5
receptor signal transduction