The adult body plan of insects is highly conserved but the developmental processes underlying its formation can vary greatly between different species. Liu and Kaufman report that hunchback, a gap gene involved in the subdivision of the blastoderm in Drosophila, has two separate roles in Oncopeltus fasciatus, the milkweed bug (see ). In Drosophila, a long germband insect, all of the body segments are specified simultaneously during the blastoderm stage. In Oncopeltus,an intermediate germband insect, only the anterior segments are proportionally represented in the blastoderm fate map; posterior segments are specified later, during germband elongation. In RNAi-based experiments, the researchers show that Oncopeltus hunchback both suppresses abdominal identity at the blastoderm stage and is required for germband growth and segmentation. Thus, although hunchback-depleted Oncopeltus and Drosophila both have a relatively normal head followed immediately by abdominal segments, the developmental events underlying this phenotype are very different.
