Chemical ecology in conservation biological control: status and emerging challenges

Over the past decade, chemical ecology has become increasingly integrated into the development of biological control programs, particularly Conservation Biological Control (CBC). Conservation Biological Control exploits a set of habitat manipulation practices to maintain and enhance the reproduction, survival, and efficacy of arthropod natural enemies that prey upon or parasitize insect pests. Specifically, chemical cues that convey information between living organisms, named semiochemicals, can enhance the management of herbivore populations by mediating interactions among plants, herbivores, predators, parasitoids, and their surrounding habitats. Nevertheless, translating mechanistic knowledge of chemically mediated interactions into reliable control of pest insect populations remains a major challenge. A central constraint is the persistent gap between results obtained under simplified laboratory conditions and outcomes observed in dynamic agroecosystems, where background odors, meteorological conditions, crop phenology, and multispecies interactions can modify semiochemical production and transmission, receiver responses, and ultimately, biological control agent efficacy. Additional priorities include moving from the study of individual compounds to ecologically realistic blends of bioactive volatiles; identifying nontarget and food-web effects; integrating semiochemical-based interventions with habitat management and selective crop-protection practices; and developing standardized field metrics that connect natural enemy recruitment with predation, parasitism, herbivore population control, and reduction in crop damage. Progress will therefore require multiscale experimentation, closer integration of analytical chemistry with behavioral and field ecology that balance efficacy, ecological safety, and operational feasibility. From this perspective, CBC involves more than enhancing the abundance or activity of arthropod natural enemies: it requires the deliberate management of information flow across multitrophic levels to establish a more predictive and mechanistically grounded framework for biological herbivore population control. Here, are reviewed the principal issues that chemical ecology should address to advance CBC, focusing on how semiochemical production, transmission, and perception vary across plant genotypes, herbivore communities, natural-enemy guilds, microbiomes, agricultural practices, and landscape contexts.