Odor tracking in insects: a multisensory behavior

Insects rely on sophisticated odor-tracking mechanisms to locate mates and food sources, or follow conspecific trails, in both two (e.g. substrate-based tracking by ants and termites) and three (e.g. airborne pheromone plume tracking by flying insects) dimensions. These behaviors rely on the integration of multisensory information and understanding them requires us to draw upon principles from odor transport physics, odor chemistry and sensory ecology. Airborne odor plumes are typically heterogeneous and turbulent, delivering chemical cues in intermittent bursts, while ground-based odor trails are more stable and localized. Hence, insects employ fundamentally distinct strategies to navigate these environments, shaped by the physical and chemical properties of the odorants. Insect odor-tracking behavior is mediated by an array of sensory modalities, including chemosensory, visual, mechanosensory and thermal inputs. Experimental approaches in both laboratory and field settings have revealed how insects integrate these cues to successfully identify odor sources under complex environmental conditions. Comparative studies, such as those examining diurnal versus nocturnal tracking, highlight how sensory prioritization shifts with ecological context, revealing adaptive neural integration mechanisms. This article reviews the behavioral strategies insects use for odor tracking in air and on the ground, focusing on the role of multisensory integration and the vulnerability of these behaviors to sensory noise. Emerging research on environmental disruptions, such as artificial light at night and air pollution, highlights the ecological threats to odor-mediated behaviors. By synthesizing insights from diverse insect taxa, we examine how sensory noise and anthropogenic change can impair essential behaviors such as foraging and mating.