Octopamine and Tyramine Receptors in Insect Physiology and Behavior

Effect of tyramine (TA) and octopamine (OA) on insect behaviour such as sex-pheromone production, egg laying and metamorphosis is discussed in detail. TA inhibits pheromone production in vitro in a dose dependent manner and dopamine (DA) has a lower inhibitory activity than TA, whereas OA has no effect, suggesting that TA is a candidate for regulating pheromone production in the pheromone gland of Bombyx mori, although other factors could be responsible for the pheromonostatic function. The inhibition of progeny formation in Drosophila melanogaster could be due to inhibition of TA-beta-hydroxylase and/or DA-beta-hydroxylase. D. melanogaster tyramine-beta-hydroxylase (DmTBH) protein with 70 kDa was purified after the recombinant nucleopolyhedrovirus isolated from B. mori (BmNPV) containing TBH gene was injected into hemocoel of fifth instar larvae of d17 B. mori strain. TA is a causative agent in pupational programming of Tribolium freemani, by inducing an increase of juvenile hormone (JH)-esterase activity, thus decreasing JH titer followed by an increase of ecdysteroid level and accelerated pupation.