Innervation and neural regulation of the sex pheromone gland in female Heliothis moths.

TLDR

Female Heliothis moths produce a species‑specific sex pheromone during scotophase, a process stimulated by PBAN and modulated by central nervous system activity that depends on photoperiodic cues. Electrical stimulation of the ventral nerve cord or peripheral nerves, axonal innervation of the gland, and neurosecretory‑like nerve branches, together with octopamine acting similarly to PBAN, show that neural and hormonal signals can stimulate pheromone biosynthesis during photophase and that regulation is more complex than previously thought.

Abstract

Female Heliothis moths normally produce their species-specific male attractant (sex pheromone blend) during scotophase, and this production is stimulated by pheromone biosynthesis activating neuropeptide (PBAN), presumably carried in the hemolymph. Several lines of evidence indicate that the central nervous system plays another critical role in this regulation. Pheromone biosynthesis was induced during photophase by electrical stimulation of the ventral nerve cord or the peripheral nerves projecting from the terminal abdominal ganglion to the pheromone gland in the tip of the abdomen. Electron microscopy further revealed that axonal branches innervate the gland tissue. Nerve branches associated with pheromone gland cells are enwrapped in glia and contain dense-core vesicles, suggesting that the innervation of the gland might be neurosecretory. Finally, the biogenic monoamine octopamine was nearly as effective as purified Heliothis zea PBAN in stimulating pheromone biosynthesis when injected into intact females during mid-photophase. Furthermore, both octopamine and PBAN stimulated significant increases in the pheromone content of the glands in isolated abdomens lacking a ventral nerve cord but only when abdomens were treated at the onset of scotophase. These data suggest that the regulation of sex pheromone production in Heliothis is more complex than previously thought. Activation of the gland appears to be governed by both neural and hormonal mechanisms, and these control mechanisms depend on photoperiodic cues.