Male moths detect female-released sex pheromones with extraordinary sensitivity. The remarkable sensory ability is based on a cooperative interplay of pheromone binding proteins in the lymph of hair-like sensilla trichodea and pheromone receptors in the dendrites of sensory neurones. Here we examined whether in Heliothis virescens the so-called 'sensory neurone membrane protein 1' (SNMP1) may contribute to responsiveness to the pheromone component, (Z)-11-hexadecenal (Z11-16:Ald). By means of immunohistochemistry and in situ hybridization we demonstrated that SNMP1 is in fact present in cells expressing the Z11-16:Ald receptor HR13 and the dendrites of sensory neurones. To assess a possible function of SNMP1 we monitored the responsiveness of cell lines that expressed HR13 alone or the combination SNMP1/HR13 to stimulation with Z11-16:Ald by calcium imaging. It was found that SNMP1/HR13 cells were 1000-fold more sensitive to pheromone stimulation compared with HR13 cells. In contrast, cells that expressed HR13 and the non-neuronal SNMP2-type showed no change in pheromone sensitivity. Overall, our reconstitution experiments demonstrate that the presence of SNMP1 significantly increases the HR13-based responsiveness of cells to Z11-16:Ald, suggesting that SNMP1 also contributes to the response of the antennal neurones and thus to the remarkable sensitivity of the pheromone detection system.

We studied the formation of protein synthesis-dependent long-term memory (LTM) in the parasitic wasp Nasonia vitripennis Walker (Hymenoptera: Pteromalidae), a parasitoid of fly pupae. Female wasps were trained in one of five different training procedures in the presence of hosts and the odour cinnamon. Six days later the reaction of the wasps towards the odour was tested in a static four-chamber olfactometer. When wasps were trained by a single drilling experience we could not find any reaction to cinnamon after 6 days. In contrast, when wasps were trained either via drilling plus host feeding, three drilling events (spaced training), 1 h training, or 24 h training including oviposition, they significantly preferred cinnamon 6 days later. Wasps which were injected the transcription inhibitor actinomycin D after a 1-h training to block protein synthesis showed normal memory retention up to 3 days, but did not react to cinnamon after 4 and 6 days. Control experiments showed no influence of actinomycin D on the natural behaviour and the general odour discrimination ability of N. vitripennis. This demonstrates that protein synthesis-dependent LTM has been formed. To our knowledge this is the first time that LTM formation after drilling plus host feeding but without oviposition is demonstrated in a parasitic wasp. These results were combined with additional findings about anaesthesia-sensitive memory, anaesthesia-resistant memory, and intermediate memory to develop a multiphase model of memory dynamics in N. vitripennis and to discuss ecological adaptations of memory formation in N. vitripennis and other parasitic wasp species.