Category Archives: Papers

Bee-ophysics in the news – Ostroverkhova lab studies bee visual response

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The Ostroverkhova group’s work on bee vision had attracted a lot of attention!

Ostroverkhova et al examined responses of wild bees to traps designed to selectively stimulate either the blue or the green photoreceptor using sunlight-induced fluorescence in the 420-480 nm or 510-540 nm region. Image credit: Rebekka D.

KATU has an interview with Oksana Ostroverkhova at: https://katu.com/news/local/wild-bees-are-attracted-to-blue-fluorescent-light-oregon-state-university-research-finds

Sci-news has an article http://www.sci-news.com/biology/bees-blue-fluorescent-light-06121.html

and there is a press release to go with their recent paper in Journal of Comparative Physiology A. https://link.springer.com/article/10.1007/s00359-018-1269-x

CORVALLIS, Ore. – Researchers at Oregon State University have learned that a specific wavelength range of blue fluorescent light set bees abuzz.

The research is important because bees have a nearly $15 billion dollar impact on the U.S. economy – almost 100 commercial crops would vanish without bees to transfer the pollen grains needed for reproduction.

“The blue fluorescence just triggered a crazy response in the bees, told them they must go to it,” said the study’s corresponding author, Oksana Ostroverkhova. “It’s not just their vision, it’s something behavioral that drives them.”

The findings are a powerful tool for assessing and manipulating bee populations – such as, for example, if a farmer needed to attract large numbers of bees for a couple of weeks to get his or her crop pollinated.

“Blue is broad enough wavelength-wise that we needed to figure out if it mattered to the bees if the light emitted by the sunlight-illuminated trap was more toward the purple end or the green end, and yes, it mattered,” Ostroverkhova said. “What’s also important is now we’ve created traps ourselves using stage lighting filters and fluorescent paint – we’re not just reliant on whatever traps come in a box. We’ve learned how to use commercially available materials to create something that’s very deployable.”

Fluorescent light is what’s seen when a fluorescent substance absorbs ultraviolet rays or some other type of lower-wavelength radiation and then immediately emits it as higher-wavelength visible light – think about a poster whose ink glows when hit by the UV rays of a blacklight.

Like humans, bees have “trichromatic” vision: They have three types of photoreceptors in their eyes.

Both people and bees have blue and green receptors, but the third type for people is red while the third kind for bees is ultraviolet – electromagnetic energy of a lower wavelength that’s just outside the range of human vision.

Flowers’ vibrant colors and patterns – some of them detectable only with UV sight – are a way of helping pollinators like bees find nectar, a sugar-rich fluid produced by plants. Bees get energy from nectar and protein from pollen, and in the process of seeking food they transfer pollen from a flower’s male anther to its female stigma.

Building on her earlier research, Ostroverkhova, a physicist in OSU’s College of Science, set out to determine if green fluorescence, like blue, was attractive to bees. She also wanted to learn whether all wavelengths of blue fluorescence were equally attractive, or if the drawing power tended toward the green or violet edge of the blue range.

In field conditions that provided the opportunity to use wild bees of a variety of species – most bee-vision studies have been done in labs and used captive-reared honeybees – Ostroverkhova designed a collection of bee traps – some non-fluorescent, others fluorescent via sunlight – that her entomology collaborators set up in the field.

Under varying conditions with a diverse set of landscape background colors, blue fluorescent traps proved the most popular by a landslide.

Researchers examined responses to traps designed to selectively stimulate either the blue or the green photoreceptor using sunlight-induced fluorescence with wavelengths of 420 to 480 nanometers and 510 to 540 nanometers, respectively.

They found out that selective excitation of the green photoreceptor type was not attractive, in contrast to that of the blue.

“And when we selectively highlighted the blue photoreceptor type, we learned the bees preferred blue fluorescence in the 430- to 480-nanometer range over that in the 400-420 region,” Ostroverkhova said.

Findings were recently published in the Journal of Comparative Physiology A. The Agricultural Research Foundation and OSU supported this research.

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Editor’s note: Images are available at http://bit.ly/2JO7ypl and http://bit.ly/2MA4080

Paper Summaries: Simultaneous fluorescence and surface charge measurements on organic semiconductor-coated silica microspheres

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Rebecca Grollman, Graham Founds, Rick Wallace and  Oksana Ostroverkhova’s paper “Simultaneous fluorescence and surface charge measurements on organic semiconductor-coated silica microspheres” has been featured by Advances in Engineering  as a key scientific article contributing to excellence in science and engineering research.  See

https://advanceseng.com/simultaneous-fluorescence-surface-charge-measurements/

for a short summary of the paper and a short video highlighting the result.

Paper Summaries – To beam or not to beam: OSU research shows sign of a misaligned jet in the gravitational wave source GW170817

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Model predictions for flux vs time(solid lines) compared to observations (symbols).
GW170817, detected on August 17, 2017, was the first multi-messenger astronomical source, seen in gravitational waves and across the whole electromagnetic spectrum. Much of the physics of this source has been understood thanks to the high quality data collected for months after the initial detection. We now know that it was due to the collision between two neutron stars, a class of very massive and compact stars that were in orbit around each other and eventually merged forming a black hole. During the collision material was flung out in all directions. Most of the material was sent in the equatorial direction, where new atoms – such as gold and platinum – were formed through rapid neutron capture. Some material was sent in the polar direction, but exactly how much and with what energy is not known, since our observing geometry is far from the polar axis. For that reason, it had been impossible to ascertain whether a short gamma-ray burst also took place with the star collision.
Short gamma-ray bursts are some of the brightest explosions recorded in present day universe. They are produced when extremely fast outflows are sent in our direction by leftover material that accretes onto a newly formed black hole. Scientists believe they should be caused by a neutron star collision, but direct evidence is not yet available. When we detect  the burst directly, it is so bright that outshines all the signs of the neutron star collision. Groundbreaking research performed by the astrophysics group led by Dr. Lazzati and accepted for publication in Physical Review Letters, however, has shown that the unusual increase of the luminosity of GW170817 over time is a sign that a short GRB did happen right after the merger, albeit along a different direction. The figure displays the model predictions (solid lines) along with the observations (symbols), showing the excellent agreement of the model with the data.