How the diet influences lepidopteran reproduction: Morpho-functional, behavioral, and endocrine aspects

In insects, diet influences the accomplishment of physiological functions, such as reproduction. The study of interactions between diet and reproduction, which involve morpho-functional, behavioral, and endocrine aspects, is necessary for identifying the features of the adaptive strategies of insects in their natural environment. This review delves into the intricate relationship between nutrition and reproductive processes in female and male Lepidoptera. Indeed, nutrient-rich diets are crucial for reproductive success by accelerating ovarian and testicular development, egg maturation, sperm synthesis and migration, and accessory sex gland maturation. Moreover, such diets boost the biosynthesis and release of sex pheromones and promote pheromonal detection by the olfactory system, thus eliciting sexual displays. These physiological and behavioral changes increase fertilization rate and offspring production, highlighting the importance of balanced diets in sustaining insect populations. Then, the review explores the molecular mechanisms by which the evolutionary conserved insulin signaling pathway acts as a transducer of nutritional inputs in linking with the regulatory actions of a major reproductive hormone, namely juvenile hormone. Finally, this review provides a greater comprehensive and integrated understanding of adult diet influence on lepidopteran reproduction, and also opens up new research avenues in the fields of agricultural pest control and ecotoxicology.