A supergene controls facultative diapause in the crop pest Helicoverpa armigera

Abstract

Summary: Many insect species, including the economically important pest Helicoverpa armigera, avoid unfavorable conditions by suspending development. This form of phenotypic plasticity—facultative diapause—is a complex trait, though its evolution and intricate genetic architecture remain poorly understood. To investigate how such a polygenic trait could be locally adapted, we explore its genetic architecture. We map a large-effect diapause-associated locus to the Z chromosome by crossing high- and low-latitude populations. By generating multiple chromosome-scale assemblies, we identify an ∼5.93-Mb chromosomal inversion that constitutes the locus. Within this inversion, 33 genes harbor divergent non-synonymous mutations, notably including three circadian rhythm genes: Period, Clock, and Cycle. CRISPR-Cas9 knockout experiments confirm that each gene is independently essential for pupal diapause. Thus, a diapause supergene arose within H. armigera via a Z chromosome inversion, enabling local climatic adaptation in this economically important crop pest.

Keywords

• CP: Developmental biology
• CP: Molecular biology