Antennal morphology and localization of a general odorant-binding protein in the great wax moth, Galleria mellonella (Lepidoptera: Pyralidae)

Abstract

The great wax moth, Galleria mellonella (L.), is a globally distributed pest for bee hives and, therefore, of significant importance for apiculture. In this study, the antennal morphology of G. mellonella was elucidated by light microscopy (LM) and scanning electron microscopy (SEM). Moreover, the putative function of the sensilla was studied by in situ hybridization of an odorant-binding protein (OBP)-encoding gene. Thus, an OBP subclass called general odorant-binding protein (GOBP) was used. Currently, GOBPs are related to the transport of sex pheromone and general volatiles in the sensilla of insects. Results indicate sexual dimorphism, with longer antennae for females than males. Sensilla morphology was similar to that reported in other moths, especially pyralids, with a total of seven types of sensilla, namely chaetica (SCH), trichodea (STR), coeloconica (SCO), styloconica (STY), auricilica (SAU), basiconica (SBA) and squamiformia (SSQ). Böhm’s bristles (BB) were also found. As expected due to the inverse sexual communication of G. mellonella, a higher abundance of pheromone-related STR subtype I, were determined in female compared to male antennae. More interestingly, we report the presence of a GOBP-encoding gene, found mainly in female STR and SCH. Therefore, the cross information between reported sensilla function and that of OBPs provides evidence to support not only the olfactory function of STR and SCH, but also the uncommon sexual communication that G. mellonella has developed.