Insect odor transduction employs different mechanisms. In the fruitfly olfactory receptor (OR) olfactory coreceptor (Orco) tetramers underly both, an insensitive ionotropic and a sensitive metabotropic odor transduction pathway coupling to adenylyl cyclase. In hawkmoths Manduca sexta patch clamp recordings of primary cell cultures of antennal olfactory receptor neurons (ORNs) revealed that the first pheromone-dependent current to be elicited was a transient Ca2+ current that resembled IP3 -dependent Ca2+ currents, but not OR-Orco-based non-specific cation currents. Thus, we hypothesized that highly sensitive pheromone transduction in the hawkmoth employs G-protein-dependent activation of phospholipase Cβ. Furthermore, ELISAs measured diurnal oscillations of octopamine-dependent cAMP- and IP3 levels in hawkmoth antennae. Thus, here, in tip recordings of antennal pheromone-sensitive trichoid sensilla in vivo, we tested, whether pharmacological interference with antagonist of phospholipase C (U73122) and of various G proteins interferes with sensitive hawkmoth pheromone transduction. We found that U73122 reduced sensitivity and kinetics of pheromone transduction daytime-dependently. Infusion of Pasteurella multocida toxin that was described to cause declines of cAMP and increases of IP3 levels had variable, not significant effects. However, pertussis toxin that decreases IP3 and increased cAMP levels, and cholera toxin activating Gαs both decreased kinetics and sensitivity of pheromone responses at the end of the hawkmoth´s activity phase. We conclude that hawkmoth pheromone transduction involves G-protein-dependent activation of a phospholipase Cβ. Pheromone transduction cascades vary daytime-dependently, since a circadian clock in ORNs makes different cyclic nucleotide and Ca2+-dependent ion channels available for signal transduction during the sleep-wake cycle of the hawkmoth. [Supported by DFG grants STE531/20-1,2 to MS and GRK2749/1]