Sexual Dimorphism in the Antennal Lobe of the Parasitoid Wasp Nasonia vitripennis: the effect of silencing transformer on glomerular architecture

Male- and female-specific insect behaviours originate from differences in brain structure and morphology which are regulated by specific genes in the so called sex-determination pathway. One of the brain regions that differs between males and females is the odour-processing center, the antennal lobe, which contains multiple glomeruli. Here we studied the differences in brain structure in the parasitoid wasp, Nasonia vitripennis to see if males had different glomeruli numbers when compared to females. For this he had to dissect the brains from a 2 mm large (or rather small) wasp, and use specific staining techniques to see how the brains from males and females differed in glomeruli numbers. We found that females have ~40 glomeruli more than males. Subsequently we silenced one of the genes in the sex determination pathway using RNA interference to shift female developments towards male development and in this way create intersexes. We then recorded the changes in brain sexual differentiation by counting glomeruli numbers in these intersexes. In this way we hoped to understand the role of the different genes in the sex determination cascade on brain development. We observed that indeed in intersexes the brain is also a mix of male and female brain characteristics with glomeruli numbers that are in between those of males and females. In this way we can better understand which gene is most important in sex-specific brain development in insects.