Molecular perspectives on life-history evolution in Bruchinae seed beetles

Phytophagous beetles represent one of the largest groups of plant-feeding insects. With about 135,000 described species, they exploit seeds, leaves, stems, and wood. Within this diversity, the subfamily Bruchinae has a distinctive ecological niche: larvae develop inside legume seeds. These beetles are major agricultural pests, responsible for up to 20% losses in legume grain value. This yield loss represents a severe problem, as legumes provide essential dietary protein for roughly 75% of people in developing countries. Despite their importance, the molecular foundations of life-history traits facilitating Bruchinae adaptation to seeds have only recently begun to be explored, leaving current knowledge sparse and fragmented. This review synthesizes current knowledge of the molecular mechanisms underlying the nutritional and digestive challenges faced by beetles during seed infestation, reproduction, and development, as well as during host shifts to novel or unusual legumes. Drawing on well-established examples, it examines key processes involved in the co-evolutionary dynamics between phytophagous insects and their host plants, while highlighting recent genomic advances that are accelerating discovery in these fields. Collectively, the review integrates both historical and contemporary molecular perspectives on life-history evolution in Bruchinae seed beetles.