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Ocellar adaptations for dim light vision in a nocturnal bee

Berry, Richard P.; Wcislo, William T. and Warrant, Eric LU (2011) In Journal of Experimental Biology 214(8). p.1283-1293
Abstract
Growing evidence indicates that insect ocelli are strongly adapted to meet the specific functional requirements in the environment in which that insect lives. We investigated how the ocelli of the nocturnal bee Megalopta genalis are adapted to life in the dim understory of a tropical rainforest. Using a combination of light microscopy and three-dimensional reconstruction, we found that the retinae contain bar-shaped rhabdoms loosely arranged in a radial pattern around multi-layered lenses, and that both lenses and retinae form complex non-spherical shapes reminiscent of those described in other ocelli. Intracellular electrophysiology revealed that the photoreceptors have high absolute sensitivity, but that the threshold location varied... (More)
Growing evidence indicates that insect ocelli are strongly adapted to meet the specific functional requirements in the environment in which that insect lives. We investigated how the ocelli of the nocturnal bee Megalopta genalis are adapted to life in the dim understory of a tropical rainforest. Using a combination of light microscopy and three-dimensional reconstruction, we found that the retinae contain bar-shaped rhabdoms loosely arranged in a radial pattern around multi-layered lenses, and that both lenses and retinae form complex non-spherical shapes reminiscent of those described in other ocelli. Intracellular electrophysiology revealed that the photoreceptors have high absolute sensitivity, but that the threshold location varied widely between 109 and 10(11) photons cm(-2) s(-1). Higher sensitivity and greater visual reliability may be obtained at the expense of temporal resolution: the corner frequencies of dark-adapted ocellar photoreceptors were just 4-11 Hz. Spectral sensitivity profiles consistently peaked at 500 nm. Unlike the ocelli of other flying insects, we did not detect UV-sensitive visual pigments in M. genalis, which may be attributable to a scarcity of UV photons under the rainforest canopy at night. In contrast to earlier predictions based on anatomy, the photoreceptors are not sensitive to the e-vector of polarised light. Megalopta genalis ocellar photoreceptors possess a number of unusual properties, including inherently high response variability and the ability to produce spike-like potentials. These properties bear similarities to photoreceptors in the compound eye of the cockroach, and we suggest that the two insects share physiological characteristics optimised for vision in dim light. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
ocelli, bee, nocturnal vision, sensitivity, polarisation sensitivity, spectral sensitivity, response dynamics
in
Journal of Experimental Biology
volume
214
issue
8
pages
1283 - 1293
publisher
The Company of Biologists Ltd
external identifiers
  • wos:000288696500014
  • scopus:79954986207
ISSN
1477-9145
DOI
10.1242/jeb.050427
language
English
LU publication?
yes
id
2bd55778-89b5-4716-a853-bdf9f9a2a5e7 (old id 1925835)
date added to LUP
2011-05-03 12:18:15
date last changed
2017-10-22 03:05:11
@article{2bd55778-89b5-4716-a853-bdf9f9a2a5e7,
  abstract     = {Growing evidence indicates that insect ocelli are strongly adapted to meet the specific functional requirements in the environment in which that insect lives. We investigated how the ocelli of the nocturnal bee Megalopta genalis are adapted to life in the dim understory of a tropical rainforest. Using a combination of light microscopy and three-dimensional reconstruction, we found that the retinae contain bar-shaped rhabdoms loosely arranged in a radial pattern around multi-layered lenses, and that both lenses and retinae form complex non-spherical shapes reminiscent of those described in other ocelli. Intracellular electrophysiology revealed that the photoreceptors have high absolute sensitivity, but that the threshold location varied widely between 109 and 10(11) photons cm(-2) s(-1). Higher sensitivity and greater visual reliability may be obtained at the expense of temporal resolution: the corner frequencies of dark-adapted ocellar photoreceptors were just 4-11 Hz. Spectral sensitivity profiles consistently peaked at 500 nm. Unlike the ocelli of other flying insects, we did not detect UV-sensitive visual pigments in M. genalis, which may be attributable to a scarcity of UV photons under the rainforest canopy at night. In contrast to earlier predictions based on anatomy, the photoreceptors are not sensitive to the e-vector of polarised light. Megalopta genalis ocellar photoreceptors possess a number of unusual properties, including inherently high response variability and the ability to produce spike-like potentials. These properties bear similarities to photoreceptors in the compound eye of the cockroach, and we suggest that the two insects share physiological characteristics optimised for vision in dim light.},
  author       = {Berry, Richard P. and Wcislo, William T. and Warrant, Eric},
  issn         = {1477-9145},
  keyword      = {ocelli,bee,nocturnal vision,sensitivity,polarisation sensitivity,spectral sensitivity,response dynamics},
  language     = {eng},
  number       = {8},
  pages        = {1283--1293},
  publisher    = {The Company of Biologists Ltd},
  series       = {Journal of Experimental Biology},
  title        = {Ocellar adaptations for dim light vision in a nocturnal bee},
  url          = {http://dx.doi.org/10.1242/jeb.050427},
  volume       = {214},
  year         = {2011},
}