Abstract
Dispersal flight is the most important and almost the only way for
primary aquatic insects to find new water habitats. During
a 30-week-long project, we monitored the flight dispersal
behaviour of aquatic beetles and bugs with using highly and horizontally
polarizing agricultural black plastic sheets laid onto the
ground. Based on the flight data of more than 45,000 individuals
and 92 species, we explored and described eight different
diel flight activity patterns. We found that seven of eight dispersal
patterns are consistent with the previous knowledge, while
three conspicuous mass dispersal periods can be identified as in
the mid morning and/or around noon and/or at nightfall. As
an exception, we found a ‘daytime’ pattern occurred exclusively
in spring, in which mass dispersal can be seen from mid
morning to late afternoon. In contrast to previous studies, we emphasize
here that the seasonality has to be considered in evaluation
of the diurnal flight activity. According to the seasons, a ‘three
code sign’ was proposed to indicate the diel dispersal
flight behaviour of a species for a year. Most of the species utilize
different diel activity patterns in different seasons. In
spring, the daytime pattern was the preferred type, but in summer
and autumn, the evening types were the most popular
patterns. We stated that the seasonal change of air temperature has a
crucial role in that a pattern could be manifested in a
given season or not and brings a need to change the diel dispersal
pattern among seasons.
Keywords
Aquatic insect dispersal
behaviour, Diel flight activity, Diurnal dispersal patterns, Pattern
shift among seasons, Air temperature dependency
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