Divergence in the Morphology and Energy Metabolism of Adult Polyphenism in the Cowpea Beetle Callosobruchus maculatus

Adult polyphenism is a prevalent form of adaptive evolution that enables insects to generate discrete phenotypes based on environmental factors. However, the morphology and molecular mechanisms underlying adult dimorphism in <i>Callosobruchus maculatus</i> (a global storage pest) remain elusive. Understanding these mechanisms is crucial for predicting the dispersal and population dynamics of <i>C. maculatus</i>. This knowledge can also provide a theoretical basis for biological control strategies. In this study, we compared the morphology of the hind wing and chest muscles, the transcriptional profiles, the energy metabolism substances, and the fecundity between the flight form and the normal form. The flight form displays a lighter overall appearance with small black spots, while the normal form lacks most flight muscles. Moreover, there are differences in the energy metabolism pathways between the two forms, including carbohydrate metabolism and oxidative phosphorylation. The flight form exhibits higher contents of carbohydrates, lipids, and mitochondrial energetic storage. The normal form exhibits better fertility but has lost its ability to fly. This is the first study to analyze the morphology and molecular characteristics of adult polyphenism in <i>C. maculatus</i> using morphological, physiological, and behavioral approaches, providing a foundational understanding of these aspects. Our study on <i>C. maculatus</i> also provides supporting evidence of a trade-off between dispersion and reproduction, where the flight form is capable of flying while the normal form has more reproductive benefits.