Functional Characterization of Abdominal-A in the Pine Caterpillar Moth, Dendrolimus punctatus

Hox genes, specifically the bithorax complex (ubx, abdominal-a, and abdominal-b), play a crucial role in specifying posterior abdominal development and serve as key regulators of germline gene development in insects. However, the function of the bithorax complex in the pine caterpillar moth, Dendrolimus punctatus, a major pine tree defoliator in China, remains largely unknown. Specifically, Abdominal-A (Abd-a) controls regional variation in abdominal segmentation in model insects such as Drosophila and Tribolium; however, its role in D. Punctatus remains unexplored. In this study, CRISPR/Cas9 was used to functionally characterize Abd-a in D. punctatus. Two target sites were selected, and the genotypes and phenotypes of the G0 and G1 generations were evaluated. Our findings indicate that knocking out Abd-a led to an abnormality in the posterior segments A2–A7, as well as the loss of appendages, mainly prolegs, and affected the thoracic T3 segmentation as well as wing development. Moreover, mutation in Abd-a also impacted anal and reproductive development. Taken together, these results demonstrate that DpAbd-a is essential for embryonic and reproductive development in D. punctatus and could be a promising target for genetic control of this devastating conifer defoliator.