• Urban lights keep insects awake at night

    From ScienceDaily@1:317/3 to All on Wed Aug 18 21:30:36 2021
    Urban lights keep insects awake at night
    Scientists reveal how the urban-related increase in nighttime light and
    heat postpones natural hibernation periods of flesh flies

    Date:
    August 18, 2021
    Source:
    Osaka City University
    Summary:
    New research sheds light on the effect urbanization has on the flesh
    fly species Sarcophaga similis. Through a series of laboratory and
    in-field experiments, scientists show that an increase in nighttime
    illumination and temperature, two of the major characteristics of
    urbanization, can postpone S. similis hibernation anywhere from
    3 weeks to a month.



    FULL STORY ==========================================================================
    A new study shows how an increase in nighttime lighting (light pollution)
    and heat from urban areas disturbs the hibernation periods of insects.


    ==========================================================================
    "The study looks at a species of flesh fly called Sarcophaga similis,
    but the results could be applicable to any animal species that relies on predictable environmental signals for biological processes like growth, reproductive behavior, sleep, and migration," said Assistant Professor
    Ayumu Mukai of Setsunan University and lead author of the study. In collaboration with Professor Shin Goto of Osaka City University, their
    findings were published in Royal Society Open Science.

    A common way of exploring the ecological effects of urbanization is
    to investigate changes in life cycles of species in the urban and
    surrounding area. Urban warming and artificial light at night are two
    of the most influential factors in this regard. As urban warming can
    increase surface temperatures anywhere between 5 -- 9DEGC, species with
    lower critical thermal optima, i.e. biological processes such as growth
    and development that occur at lower environmental temperatures, are disproportionately affected. Due to large fluctuations throughout the day
    and year, temperature can be an unreliable cue for species to determine
    when to sleep, breed, migrate, etc., rendering this cue supplemental to
    a biological response to seasonal changes by monitoring day length --
    an ability called photoperiodism. Increased nighttime light can throw
    off an insect's photoperiodism, yet few studies have focused on the
    effect urban warming and artificial light at night have had on insects
    in their natural habitat.

    "Recognizing the conditions urbanization brings upon insects where
    they actually live would be a great step forward in mitigating any
    negative effects," Shin Goto said. To understand this, the team
    conducted experiments indoors and outdoors. As S. similis typically
    enters hibernation during autumn, laboratory hibernation was induced
    in flies under two average October temperatures (20DEGC and 15DEGC),
    with varying levels of illuminance to mimic bright urban to dark rural
    areas. They found that the percentage of flies entering hibernation
    decreased as illumination increased and as the temperature increased
    from 15DEGC to 20DEGC -- suggesting the higher temperatures found in
    urban areas are associated with higher nighttime illumination.

    In the field, the team measured when the insects entered hibernation in
    two city locations: a site with nighttime lighting at around 0.2 lux (the brightness of a full moon in a clear sky), and another with nighttime
    lighting at around 6 lux, which is equivalent to a residential area or
    street at night.

    At sites with dark nights, most flies enter hibernation between October
    and November while at sites with increased nighttime light, they did
    not enter hibernation until after November. The team also compared
    urban areas with illumination of about 0.2 lux with rural areas of
    almost 0 lux. The percentages of flies entering hibernation in rural
    areas increased from late September, around 3 weeks earlier than their
    urban counterparts. Temperatures were also 2.5DEGC higher in the cities,
    which is thought to be the cause for the delay in hibernation.

    While these findings do suggest that nighttime lighting, which supports
    our daily lives, is disrupting the seasonality of insects, "urban
    environments are complex, with nighttime illumination and temperatures
    varying within the same neighborhood and between different cities," Ayumu
    Mukai pointed out, "and our work on a single flesh fly does not elucidate
    the photoperiodic response of other insects." To understand the extent to which our cultural life influences other organisms, Shin Goto continued, "Future studies with a variety of insect species at different sites,
    in cities with different climatic regions would clarify what levels
    of light pollution and urban warming affect insect seasonal adaptation" ========================================================================== Story Source: Materials provided by Osaka_City_University. Note: Content
    may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Ayumu Mukai, Koki Yamaguchi, Shin G. Goto. Urban warming and
    artificial
    light alter dormancy in the flesh fly. Royal Society Open Science,
    2021; 8 (7): 210866 DOI: 10.1098/rsos.210866 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2021/08/210818130525.htm

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