Pheromone gland development and monoterpenoid synthesis specific to oviparous females in the pea aphid.

Glandular tissues of scent plaque are differentiated from the fourth instar in sexual females, while parthenogenetic females lack the glandular cells. Only the downstream steps of the mevalonate pathway appear to occur in scent plaques on hind tibias of sexual females, although the upstream steps may occur somewhere in other body parts.