Reduced avian predation on an ultraviolet-fluorescing caterpillar model

Many caterpillars exhibit patterns of ultraviolet (UV) fluorescence, although its purpose is unclear. We used realistic plasticine models of a fluorescing caterpillar species, the Polyphemus moth, Antheraea polyphemus (Lepidoptera; Saturniidae), adorned with fluorescent paint treatments and unpainted controls to quantify bird predation in two hardwood forested regions of New York State, United States of America. In separate field studies, significantly more birds struck deployed model caterpillars that had no UV fluorescence. More strikes on unpainted and clear paint treatments suggest paint itself did not impact predation, whereas similar predation attempts on bird and human-visible fluorescent dummies suggest that UV fluorescence and not UV reflectance was responsible for the observed effect. A second study found the dummy’s location on the tree was also important, but the low number of bird strikes limited analyses. Although our results do not identify a mechanism, fluorescence may function to deter or avoid predation. Our study contributes to a growing body of work investigating the importance of UV patterns in arthropods and highlights a potentially fruitful area of future research on predator–prey relations.

Fluorescent Paint before Day-Glo

The principles of fluorescence were discovered and worked out by the middle of the nineteenth century. Yet the discovery of fluorescent paint—at least according to internet sites and some books —did not occur until the 1930s. The Switzer brothers developed fluorescent paints while one of them had enforced inactivity while recuperating from an injury. This much is true, but surely, with all the facts of fluorescence available, someone must have made fluorescent paints before mthe SWitzers. This essay looks into those early efforts, and shows how what the Switzers did was different.

A Comparison of Flat White Aerosol and Rhodamine (R6G) Fluorescent Paints and Their Effect on the Results of Tomographic PIV Measurements

Methods for reducing surface reflections during PIV measurements are commonly discussed, but the effects of those surface reflections on PIV measurements are generally neglected. In this study, a comparison of light gathering characteristics of an experimental tomographic PIV system is made using a bluff body model that is coated: i) first, with a commercially available flat white aerosol paint and ii) second, with an airbrushed Rhodamine (R6G) fluorescent paint. For each coating, PIV measurements are compared from flow regions that are affected by either direct or indirect reflections. Measurements show that very little incident light is absorbed at white boundaries, producing strong light reflection; this effect, in turn: i) saturates the light signal from far-removed suspended particles and ii) greatly reduces the signal-to-noise ratio for particles situated even close to the receiving optics. By contrast, Rhodamine (R6G) fluorescent paint provides excellent surface reflection mitigation when paired with the 532 nm filters, producing a signal-to-noise ratio sufficient to allow uniform imaging of particles across the entire calibrated volume.

Carbon nanodot–ORMOSIL fluorescent paint and films

Room temperature synthesis of micelle-protected highly fluorescent carbon nanodots (CNDs) and fabrication of scratch-resistant CND–ORMOSIL films and paint.