June 29, 2022
Release Subtitle:
Researchers find that scorpionflies from different locations use varying mating and courtship tactics
Release Summary Text:
Alternative mating strategies of the Japanese scorpionfly have been
studied sparingly over the years, primarily focusing on individual
populations. Now, two scientists from Okayama University compare the
mating habits of male Japanese scorpionflies from two locations—Aichi
and Okayama—and reveal that the weaker males of these regional
populations adopt distinctly different mating tactics to attract female
scorpionflies after losing to the stronger males, possibly indicating a
genetic influence in their mating behavior.
Full text of release:
Owing to the high competition and the prevalence of natural selection,
many male insects must develop alternative tactics to mate with a
female. Weaker males who lose in a competition (or loser males) may
resort to hovering or sneaking around in order to find a mate. Recent
studies have also shown that alternative mating behavior is influenced
by environmental factors such as food availability, predation, and
population density. For example, scorpionflies—which are often used to
study the mating behavior of insects—use three alternative mating
tactics—gifting nutritious saliva, gifting food, and forced mating—to
obtain a mate. Male Japanese scorpionflies also employ feeding mating
(i.e., mating while females feed without gifting them anything or
releasing pheromones).
Previous studies looking at alternative mating tactics in scorpionflies
have shown that the weaker males of closely-related species employ
varying methods to procreate, however no research has been done to find
the alternative mating tactics of males within the same species from
different geographical locations. To this end, Dr. Ryo Ishihara (who is
affiliated to the School of Agriculture and a recipient of the Special
Educational and Research Fellowship) and Professor Takahisa Miyatake
(from the Faculty of Environmental and Life Science) of Okayama
University, Japan, published a study in the Journal of Ethology
on 15 June 2022. This study details the differences in alternative
mating tactics of Japanese scorpionflies hailing from two different
places—Aichi and Okayama prefectures in Japan.
“A recent study among scorpionflies from
Okayama reported their mating behavior and I noticed the results were
very different from those reported in previous studies among
scorpionflies from Aichi. This piqued my curiosity, and I wanted to
verify whether behavioral differences were really occurring between the
two regions,” said Dr. Ishihara, who takes an avid interest in entomology.
The researchers observed mating behaviors in a total of 25 males in
Aichi, and 30 males almost 300 km away in Okayama, over a period of six
hours in designated feeding areas. They noticed that one of the first
behaviors in both the populations of loser males was waiting.
The loser males of Okayama resorted to ‘sneaking’ back into the feeding
area, where they positioned themselves near the food offered by the
winner male as a nuptial gift and waited till another female arrived.
They would then present the food as a nuptial gift and attempt to mate
with this female. Of the 28 loser males who employing this tactic, 24
successfully mated. On the other hand, 17 males among the scorpionflies
in Aichi ran away, seven were found ‘sneaking’ (though even these
scorpionflies left after one or two failed attempts at mating), and one
attempted to forcefully mate with visiting females.
A significant number of defeated male scorpionflies from the Aichi
population, the researchers concluded, chose to leave the feeding area
while a majority of Okayama males preferred ‘sneaking’ and trying to
mate again. It was also noticed that the defeated males from Okayama
waited longer than the ones from Aichi.
Why was this so?
“Well, there are certain factors that
are thought to influence alternative mating in Japanese scorpionflies.
One of these is the frequency and number of females visiting the feeding
areas,” Dr. Ishihara explains. Females in Okayama appeared more
frequently and in greater numbers in feeding areas. As a result,
defeated males waited longer and used ‘sneaking’ tactics for successful
mating with visiting females. The females in Aichi visited the feeding
areas less frequently, leading to defeated males who looked for other
feeding areas, or resorted to attempts at forceful mating.
The findings in the wild were corroborated with laboratory experiments.
From these results, the researchers inferred that there is also a
genetic component that influences alternative mating and courtship
habits.
Dr Ishihara emphasized the importance of the study and said, “This
is the first example of two regionally different populations of the
same species of scorpionfly showing variations in alternative mating
tactics. Our research may be used to understand the long-term
environmental indicators of habitat, predict the strength and direction
of sexual selection, and identify early factors in the evolution of
mating tactics.”
Release URL:
https://www.eurekalert.org/news-releases/957073
Reference:
Differences in mating tactics performed by males of two local populations of the Japanese scorpionfly Panorpa japonica
Journal: Journal of Ethology
DOI:10.1007/s10164-022-00753-2
Contact Person:Ryo Ishihara
Dr. Ryo Ishihara is a Fellow of the Special Educational and Research
Fellowship and is affiliated to the School of Agriculture at the Okayama
University in Japan. He has a total of eight publications to his name
with his primary focus being ethology and animal behavior. His most
recent works include mating tactics of scorpionfly, death feigning in
beetles, and swarming behavior of mayfly.
https://www.okayama-u.ac.jp/eng/research_highlights/index_id163.html
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