The highest expressed and extremely male-biased gene Nasvi2EG017727 is a fatty acid desaturase responsible for male-derived sex pheromone synthesis. (A) IGV browser screenshot showing Nasonia adult female (Top) and male (male) RNA-seq coverage (on log scale), exon–exon junctions, and read alignments in Nasvi2EG017727 gene region. (B) Neighbor-joining phylogenetic tree for the fatty acid desaturase family in Nasonia (N. vitripennis, blue), honey bee (Apis mellifera, red), ant (Camponotus floridanus, green) and fly (D. melanogaster, black). Male- and female- biased genes with greater than fourfold sex differences in Nasonia were plotted with a blue/red box indicating the degree of sex-biased expression. (C–F) Barplot of RNA-seq expression level (log2FPKM) in N. vitripennis and N. giraulti males and females for selected Nasonia genes in fatty acid desaturase family: Nasvi2EG017727 (C), Nasvi2EG021420 (D), Nasvi2EG009037 (E), and Nasvi2EG002222 (F). Statistical significance was calculated using edgeR (ns: q-value > 0.05; ***q-value < 0.001).