The 118th Meidai Cafe ☕ "Why do insects give gifts? ~Mysterious insect behaviors and brain mechanisms~"
June 20, 2025 (Fri) we held the 118th Meidai Cafe "Why do insects give gifts? ~Mysterious insect behaviors and brain mechanisms~" online (Zoom) 🧐. Over 130 people who love insects and living creatures participated.
Our guest this time is T-GEx Fellow and Lecturer at the Graduate School of Science/Institute for Advanced Research, Nagoya University, |Ryoya Tanaka 🦟.
T-GEx (Tokai Pathways to Global Excellence) is a project promoted by the Tokai National Higher Education and Research System to "cultivate pioneers of knowledge who solve global issues," and is a program that trains young researchers to become world-class PIs.
Bottom: MC, Yoshikazu Hanada, External Relations, Matsuzakaya Nagoya Store
Top left: MC, Tomoe Tsuboi, URA, Academic Research & Industry-Academia-Government Collaboration, Nagoya University (the author 🤫.)
➤ The coffee served at the Meidai Cafe, as always, was provided by R ART OF COFFEE this time as well. This time it was "Honduras El Durazno Farm Coffee." It is characterized by a fragrant breeze, a sweetness like brown sugar, and a gentle acidity.
➤ Matsuzakaya The theme for summer 2025 gifts is "Connecting thoughts." Please check it out!
➤ Insect behavior is full of mysteries!
Mr. Tanaka has loved insects since he was a child. He says he was drawn into the world of insects from that "love," and began investigating their mysterious ecology and behavior ☺️. And, in order to unravel the question of why that behavior occurs, he is conducting research on brain neural mechanisms. He is investigating the mysterious courtship behavior of fruit flies and the mysterious behavior of crickets that live in ant nests. Insect behavior is full of mysteries, isn't it? This time, Mr. Tanaka talked to us about the mysterious courtship behavior of fruit flies and its neural circuits 🧐.
➤ What is animal courtship behavior?
When we humans express love to someone we like... there are methods such as dancing, singing, and giving gifts. So, what ways do animals have to express love?
Now, here is a quiz for everyone from Mr. Tanaka! Which of the following four animal courtship behaviors actually exist? (Multiple answers allowed.)
The answer is... please watch the video 🤗!
It seems that these courtship behaviors can be seen in various animals such as birds and insects. The way of expressing love is no different from humans 🤭. Such courtship behavior actually seems to be determined by genes.What kind of genes are at work, and what kind of brain neural circuits are they controlled by?To clarify this, Mr. Tanaka continues his research every day. This time, he taught us about fruit flies, which engage in the interesting courtship behavior of "giving gifts."
What kind of gift could it be... ??
The gift they give... is "the contents of their stomach." The male vomits up the contents of what he has eaten and presents it to the female 😮. That is a bit of a surprising gift 😅.
➤ How does the courtship behavior of fruit flies occur?
What kind of genes are at work in such gift-giving behavior? Through Mr. Tanaka's research, it has been found that the |fruitless (fru) gene plays an important role in the courtship behavior of giving gifts in the fruit fly brain.
Next, they investigated what kind of neural circuits lead to gift-giving behavior. As a result, it was found that forcibly activating the neural circuits that possess the fru gene led to the "vomiting" behavior of creating a gift.
➤ The circuit of the heart that gives, the mystery of the feeling of receiving
From these results, it was possible to clarify that the neural circuit possessing the fru gene plays an important role in gift-giving behavior. However, this neural circuit possessing the fru gene consists of about 2,000 nerve cells. It is said that it is not yet known how many of these cells are actually involved. The influence of a single gene is so great... I was surprised by that, but I am also surprised that there are 2,000 cells involved.
We have come to understand the mechanism by which males give gifts to females, but conversely, what about the brain activity of "happy 💖" or "dislike 💔" when a female receives a gift...? Actually, it seems it is not yet known. If it were a human, it might show on their face, but with insects, that is not the case... 😅 What kind of mechanism is there? Mr. Tanaka says he would like to continue his research in the future. I am looking forward to the day that mystery is solved.
➤ "It's interesting because it's easy to understand!" — Participant feedback and responses from Mr. Tanaka
There were also surprised comments from participants, such as, "I had no idea the brain mechanisms of fruit flies were understood in such detail!" Mr. Tanaka skillfully handles the brains of fruit flies, which are less than 1 mm in size. Many participants commented that they could feel the researcher's spirit in that work 🤗. Furthermore, we received happy comments saying, "Because it was easy to understand, I could understand it, and because I could understand it, it was interesting!"
Thank you all very much for your many comments and questions. Below are the responses from Mr. Tanaka regarding the advance questions and the questions and comments that could not be answered during the event.
Q. When a male gives a gift, does he find the female first and then look for a gift, or does he look for a female while carrying a gift? Also, if the gift is refused, does he look for another female? Or does he offer a different gift to the same female?
A. It varies by insect species, but I think all the patterns you asked about exist. In the case of fruit flies that give gifts, if a female is present, the male will court her even if he does not have a gift (is hungry).
Q. During the courtship period, do males suppress their appetite? Or do they ever eat the gift food themselves?
A. In the case of fruit flies that give gifts, the "contents of the gift" are also food for the male himself, so I think there are times when he eats it. It is very interesting how males allocate food resources (whether to use them as gifts or eat them themselves). I would definitely like to investigate this.
Q. How do insects understand the meaning of a gift?
A. This is a difficult question. When the gift is food, it is thought that nutritional value and the like are the deciding factors in the judgment. However, I think various other possibilities can also be considered.
Q. I am curious and puzzled by the fact that insects give fakes during nuptial gift-giving. Is there an intention to deceive? (Are females also somewhat happy? I am also curious about the wrapping that is wrapped around with silk.)
A. It is difficult to know what intentions insects have when they act, but perhaps it is a strategy to distract the female with a fake gift and attempt to mate while she is distracted.
Q. Does the act of insects giving gifts to each other have a connection to emotions through brain function?
A. In Drosophila melanogaster, it is known what kind of neural circuits are at work during courtship communication using sound. It is thought that something like emotion is generated by the functioning of such circuits. In the case of gifts, it is possible that similar circuits are at work, and some kind of emotion-like state is being generated.
Q. Is there a tendency for males who engage in more nuptial gift-giving behavior to have a higher mating success rate?
A. In fruit flies that give gifts, previous research has shown that males who engage in more nuptial gift-giving behavior have a higher mating success rate.
Q. Are there differences in intelligence among insects?
A. It is known that memory and other abilities differ between insect species. For example, among insects, bees that visit flowers to collect nectar are thought to firmly remember information about flowers. It may be that intelligence, including memory, differs depending on the life history (way of life?) of each insect species.
Q. Are there no individual differences in the behavior of flies?
A. It is known that there are individual differences in behavioral patterns and the like even in flies.
Q. Do fruit flies usually fly without making sound, or does the sound they make when flying have a special frequency for their song?
A. I believe they also make sounds when flying, but I suspect the type of sound produced is different from that during courtship.
Q. Is there a set pattern for the love songs of Drosophila melanogaster, or is it original to each individual?
A. While it varies slightly depending on the individual and environmental conditions, it is known that Drosophila melanogaster sings a love song with a rhythm specific to its species.
Q. Do you release the fruit flies with modified genetic information after observing them? Or do you dispose of them to prevent genetic contamination?
A. To ensure genetically modified organisms do not escape into the wild, we conduct observations in a properly equipped laboratory and freeze them to deactivate them after the experiment is finished.
Q. Are there any methods to activate the nerve cells of fruit flies other than light stimulation?
A. Besides light stimulation, there is also a method to activate nerve cells using heat.
Q. Some bird species form pairs; are there any insect species that form pairs?
A. There are indeed known insect species that form pairs and raise their young.
Q. Evolutionarily speaking, which appeared first: the courtship behavior of nuptial gifting or singing?
A. Given the fact that many Drosophila species court with songs while only a few species give gifts, I speculate that singing came first. However, it is not accurately known which came first evolutionarily.
Q. Do insects store the gifts they receive?
A. In the case of fruit flies that give gifts, they do not store them but eat them immediately.
➤ Finally, just a little bit... about the next step
Has Mr. Tanaka's talk today changed the way you look at insects a little? The world of insects, which perform very interesting behaviors despite their small size, is still full of mysteries 😊.
Currently, Mr. Tanaka is steadily conducting experiments to clarify which of the 2,000 nerve cells that control gift-giving behavior are important, and what kind of nerve cells they are.
Mr. Tanaka says that by understanding this courtship behavior, it might be possible to suppress the reproduction of specific insects in the future. He plans to continue his research with an eye toward the possibility that interesting courtship behaviors could lead to pest control. Perhaps there is a world where insects called pests and humans live happily in separate worlds.
We will continue to do our best to make the Nagoya University Cafe an even better event. Thank you all for your continued support 😊.Once the video distribution is ready, I will post the link below, so please wait a little longer.
➤ The video is now available!
Thank you very much for your patience! The video is ready 🤗. Please take a look via the YouTube link below!
As briefly mentioned during this event, Dr. Tanaka's latest research has been published. Please feel free to check it out below👇👇👇.
Report: Chie Tsuboi (Nagoya University URA)
➤Related Links
| Ryoya Tanaka (Mr.)
The Delicate Love Life of Fruit Flies | Ri philosophia online
Matsuzakaya Nagoya Store x Nagoya University Collaboration Site "Meidai Hakase's Magnifying Glass"
#Nagoya University Graduate School of Science