How day- and night-biting mosquitoes respond differently to colors of
light and time of day
Discovery may lead to innovation in harmful insect control

Date:
July 27, 2020
Source:
University of California - Irvine
Summary:
In a new study, researchers found that night- versus day-biting
species of mosquitoes are behaviorally attracted and repelled by
different colors of light at different times of day. Mosquitoes are
among major disease vectors impacting humans and animals around
the world and the findings have important implications for using
light to control them.



FULL STORY ==========================================================================
In a new study, researchers found that night- versus day-biting species
of mosquitoes are behaviorally attracted and repelled by different colors
of light at different times of day. Mosquitoes are among major disease
vectors impacting humans and animals around the world and the findings
have important implications for using light to control them.


==========================================================================
The University of California, Irvine School of Medicine-led team studied mosquito species that bite in the daytime (Aedes aegypti, aka the Yellow
Fever mosquito) and those that bite at night (Anopheles coluzzi, a member
of the Anopheles gambiae family, the major vector for malaria). They
found distinct responses to ultraviolet light and other colors of light
between the two species. Researchers also found light preference is
dependent on the mosquito's sex and species, the time of day and the
color of the light.

"Conventional wisdom has been that insects are non-specifically attracted
to ultraviolet light, hence the widespread use of ultraviolet light
"bug zappers" for insect control. We find that day-biting mosquitoes are attracted to a wide range of light spectra during the daytime, whereas night-biting mosquitoes are strongly photophobic to short-wavelength
light during the daytime," said principal investigator Todd C. Holmes,
PhD, a professor in the Department of Physiology and Biophysics at the
UCI School of Medicine. "Our results show that timing and light spectra
are critical for species-specific light control of harmful mosquitoes."
The new study titled, "Circadian Regulation of Light-Evoked Attraction
and Avoidance Behaviors in Daytime- versus Nighttime-Biting Mosquitoes,"
is published in Current Biology. Lisa S. Baik, a UCI School of Medicine graduate student researcher who recently completed her PhD work, is
first author.

Mosquitoes pose widespread threats to humans and other animals as
disease vectors. It is estimated historically that diseases spread
by mosquitoes have contributed to the deaths of half of all humans
ever to have lived. The new work shows that day-biting mosquitoes,
particularly females that require blood meals for their fertilized eggs,
are attracted to light during the day regardless of spectra. In contrast, night-biting mosquitoes specifically avoid ultraviolet (UV) and blue
light during the day. Previous work in the Holmes lab using fruit flies
(which are related to mosquitoes) has determined the light sensors and circadian molecular mechanisms for light mediated attraction/ avoidance behaviors. Accordingly, molecular disruption of the circadian clock
severely interferes with light-evoked attraction and avoidance behaviors
in mosquitoes. At present, light-based insect controls do not take into consideration the day versus night behavioral profiles that change with
daily light and dark cycles.

"Light is the primary regulator of circadian rhythms and evokes a wide
range of time-of-day specific behaviors," said Holmes. "By gaining an understanding of how insects respond to short wavelength light in a species-specific manner, we can develop new, environmentally friendly alternatives to controlling harmful insects more effectively and reduce
the need for environmentally damaging toxic pesticides."

========================================================================== Story Source: Materials provided by
University_of_California_-_Irvine. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Lisa S. Baik, Ceazar Nave, David D. Au, Tom Guda, Joshua A. Chevez,
Anandasankar Ray, Todd C. Holmes. Circadian Regulation of
Light-Evoked Attraction and Avoidance Behaviors in Daytime-
versus Nighttime-Biting Mosquitoes. Current Biology, 2020; DOI:
10.1016/j.cub.2020.06.010 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200727194703.htm

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