Olfaction in the Anthropocene: NO3 negatively affects floral scent and nocturnal pollination.

There is growing concern about sensory pollutants affecting ecological communities. Anthropogenically enhanced oxidants [ozone (O3) and nitrate radicals (NO3)] rapidly degrade floral scents, potentially reducing pollinator attraction to flowers. However, the physiological and behavioral impacts on pollinators and plant fitness are unknown. Using a nocturnal flower-moth system, we found that atmospherically relevant concentrations of NO3 eliminate flower visitation by moths, and the reaction of NO3 with a subset of monoterpenes is what reduces the scent's attractiveness. Global atmospheric models of floral scent oxidation reveal that pollinators in certain urban areas may have a reduced ability to perceive and navigate to flowers. These results illustrate the impact of anthropogenic pollutants on an animal's olfactory ability and indicate that such pollutants may be critical regulators of global pollination.

A Fruitful Endeavor: Scent Cues and Echolocation Behavior Used by Carollia castanea to Find Fruit.

Frugivores have evolved sensory and behavioral adaptations that allow them to find ripe fruit effectively, but the relative importance of different senses in varying foraging scenarios is still poorly understood. Within Neotropical ecosystems, short-tailed fruit bats (Carollia: Phyllostomidae) are abundant nocturnal frugivores that rely primarily on Piper fruits as a food resource. Previous research has demonstrated that Carollia employs olfaction and echolocation to locate Piper fruit, but it is unknown how their sensory use and foraging decisions are influenced by the complex diversity of chemical cues that fruiting plants produce. Using free-ranging C. castanea and their preferred food, Piper sancti-felicis, we conducted behavioral experiments to test two main hypotheses: (1) foraging decisions in C. castanea are primarily driven by ripe fruit scent and secondarily by vegetation scent, and (2) C. castanea re-weights their sensory inputs to account for available environmental cues, with bats relying more heavily on echolocation in the absence of adequate scent cues. Our results suggest that C. castanea requires olfactory information and relies almost exclusively on ripe fruit scent to make foraging attempts. Piper sancti-felicis ripe fruit scent is chemically distinct from vegetation scent; it is dominated by 2-heptanol, which is absent from vegetation scent, and has a greater abundance of ß-caryophyllene, ß-ocimene, γ-elemene, and α-cubebene. Although variation in echolocation call parameters was independent of scent cue presence, bats emitted longer and more frequent echolocation calls in trials where fruit scent was absent. Altogether, these results highlight the adaptations and plasticity of the sensory system in neotropical fruit bats.

Los frugívoros han evolucionado adaptaciones sensoriales y conductuales que les permiten encontrar frutos maduros de manera efectiva, pero aún existe una falta de conocimiento sobre la importancia relativa de los diferentes sentidos que los frugívoros utilizan en diferentes escenarios de forrajeo. Dentro de los ecosistemas neotropicales, los murciélagos de cola corta (Carollia: Phyllostomidae) son frugívoros nocturnos abundantes que dependen principalmente de los frutos de Piper como recurso alimentario. Previamente se ha demostrado que Carollia emplea el olfato y la ecolocalización para encontrar frutos de Piper, pero se desconoce cómo su uso sensorial y decisiones de forrajeo están influenciados por la compleja diversidad de señales químicas producidas por las plantas. En este trabajo, utilizamos C. castanea y su especie de frutos preferida, Piper sancti-felicis, para llevar a cabo experimentos conductuales y probar dos hipótesis principales: (1) las decisiones de forrajeo de C. castanea son incitadas principalmente por el aroma del fruto maduro y, en segundo lugar, por el aroma de la vegetación, y (2) C. castanea modula el uso de sus sentidos de acuerdo a las señales ambientales disponibles y utiliza la ecolocalización en mayor grado en ausencia de señales olfativas adecuadas. Nuestros resultados sugieren que C. castanea requiere información olfativa y se basa casi exclusivamente en el aroma del fruto maduro para hacer intentos de forrajeo. El aroma del fruto maduro de P. sancti-felicis es químicamente distinto al aroma de su vegetación; está dominado por 2-heptanol, el cual está ausente del aroma de la vegetación, y tiene una mayor abundancia de ß-cariofileno, ß-ocimeno, γ-elemeno, y α-cubibeno. Aunque encontramos que la variación en los parámetros de llamadas de ecolocalización es independiente de la presencia de diferentes señales aromáticas, los murciélagos emitieron llamadas de ecolocalización más largas y frecuentes en los experimentos donde el aroma de fruto estaba ausente. Conjuntamente, estos resultados destacan las adaptaciones y plasticidad del sistema sensorial de los murciélagos frugívoros neotropicales.