The Roles of the Various Forms of Communication Used By Butterflies

From Animal Communication 2020

Butterfly communication is a complex process that does not receive as much attention as other species. Butterflies belong in the order Lepidoptera translated from Greek, Lepidos means scales and ptera means wing. There are over 28,000 species of butterfly being the second largest group of insects worldwide (Ch 2014). The laws of natural selection apply to butterflies as they do all other biological organisms, therefore, certain forms of communication may have different purposes and be more useful in different areas. Butterflies are a good indicator of a local environment since they pollinate plants, provide population control for some insects, and are a large food source for some predators (Korpella 2018). Learning their communication patterns can allow humans to better understand when and why butterfly species are thriving or hurting, which can be a sign of a healthy or unbalanced ecosystem.

When discussing butterfly communication, there are a few distinct methods butterflies prefer when sending and receiving signals. Those are acoustically through wing vibrations, which only a small number of butterflies use to communicate, visually through UV reflection, and chemically through odours and pheromones. There are mechanisms that butterflies have adapted along with their chosen communication form that aid in species and sex recognition, mating behavior, predator avoidance, and territorial dominance. Certain types of communication are more effective in specific situations while others are more effective in other situations. Some butterfly species use all forms of communication while some strictly use one as this is how some species have adapted for the best form of communication. Butterflies are unique in that they have multiple ways they can exchange information and some species have learned which method works best for them. Depending on what info they’re searching for, they will use a different method.

Necessary Anatomy Parts of a Butterfly during Communication

Sound Communication

Many butterflies use sound as their primary form of communication. There are blue and white long winged butterflies that emit the tiniest clicks when they are near other butterflies (Lockette 2004 par. 2). Another handful of studies have analyzed this type of sound communication (Barbero et. al. 2009, Travassos & Pierce 1999, Yong 2018). It has also been found that larvae, juveniles, and adults communicate using a few types of sound (Travassos & Pierce 1999). This behavior was first spotted when the blue and white long winged butterflies chased another butterfly species out of their territories while clicking. They found the butterflies also clicking to their own species. They primarily clicked while fighting or during rest when they congregated at night. When researchers investigated the clicking recordings further, they realized that the clicks were most apparent in times of aggression or territoriality. Charles Darwin discovered another genus of butterflies in 1874, Hamadryas, who used clicking noises to attract possible mates (Lockette par. 12). It’s been discovered that certain species of butterfly possess ear-like organs that feel or pick up clicks from other butterflies, which is another finding that supports the idea that sound is a viable form of communication in butterflies. Interestingly, it has even been thought that using butterflies’ ears could be of potential use for human hearing aids because they can be used as “miniature microphones,” which puts into perspective how powerful their hearing is (Lockette par. 4).

In another study conducted by Professor Yack from Carleton University, it was discovered that butterflies in the species nymphalids like monarchs, morphos, emperors, and admirals actually have ears at the base of the wings, which supports that some species of butterfly can hear and produce sounds (Yong 2018 par. 2). Their ears consist of membranes that are tightly pulled over ovular holes that vibrate when sounds come into contact with them which then release electrical signals into the butterfly’s nerves. Yack also noticed that another group of nymphalids called Satyrinae have odd veins on the tops of their wings, which are common in all butterflies. She suggested that maybe veins help butterflies hear better since they lie so close to the Satyrines’ ears. When they conducted the experiment to reveal whether the veins aided in their hearing, they found that they are part of the ears. The veins act as another tool that gathers sounds and brings them closer to the ears at the base of their wings like how the outer ear on humans works or like a hearing aid. These researchers hypothesized the ears were used for predator recognition and location, which is better for their overall survival. They can hear the same frequencies as other small prey organisms like rabbits and lizards.

In another study done on larval and juvenile butterflies from Australia, Jalmenus evagoras, Mark Travassos and Naomi Pierce from Harvard University discovered that they produce substrate-borne vibration signals from pupal and larval butterflies. The pupae stridulate when there are conspecific larvae around. These stridulent sounds are important for mutualism in ant guards on the protection of the imperial butterfly’s larvae. This form of communication in unrelated species is quite rare to capture in a study. In pupae there possess a file of teeth on the front of one of the abdominal segmented grates against the opposite plate on the back side of the fifth abdominal segment. These plates could be made up of tubercles or ridges to produce the sound. This study found that pupae of J. evagoras occur in three different situations, while resting, when disturbed, and in the presence of attendant ants and larvae. The calls were important in attracting ants to attend the larvae. The larvae used sound by grunting, hissing and drumming. The calls of the imperial blue butterfly pupae and larvae are significant in the survival of the species through mutualism with a species of ant.

A study conducted by Barbero and his research team focused on the mimicking of queen ants by a species of butterfly, Maculinea rebeli. This form of communication works in favor of the butterfly as a parasite in search of a host for larvae. The larvae are fed by ant workers which in turn allows the next generation of butterflies to live on. The sounds mimicked from the queen ants elicited higher amounts of protection and care for the butterfly larvae. This mechanism developed over time by this species of butterfly and ensures the safety of their young. It has been shown that sound communication helps the survival of butterfly species through predator deterrents, interspecies mutualism, mate attraction or even mimicry of sounds from parasitic butterflies for potential hosts.

Visual Communication

In visual communication among butterflies, they rely on their color for courting, mating or protection. Adult butterflies primarily use two different signals, one is used for protection against predators and the other is used for intraspecific communication. Two common ways for butterflies to interact and mate is through visual communication or ultraviolet communication. Both of these prove useful and include a receiver and a sender. While butterflies are quite “pretty” to view, there are more reasons behind the impressive coloration. Butterflies are incapable of protecting themselves physically, therefore the colors on their wings help protect them against predators as it stands for a sign of toxicity.

According to a journal article on Royal Society, “their low divergence in color patterns contrasts with great differentiation in the chemistry of their scent-organ volatiles.” The color and patterns on the butterflies aid in camouflage, mate attraction and can be interpreted as a warning signal to some predators. Charles Darwin proposed that the ventral wing is displayed as a perched posture is an effect for protection from predators (Hirose, 2002). When it comes to courting, males are actually the elegant, showy ones because they have to do the pursuers in the courtship. Males are able to distinguish if the butterfly is male or female, by looking at the wing size and colors. Males will rely more on cues to locate and identify females (Silberglied 1978). Visual cues come into a big part of the beginning part of courtship, especially the chase.

It is known that butterflies have extreme color sight. They are able to see ultraviolet light and can see moving objects faster than humans. According to the article, butterflies have many different types of photoreceptors, that it allows the colors to be much more vibrant. (Fukuda er al., 1984) This helps butterflies mate, because they are able to see different variations in colors, and males can spot their rivals even if the rival is flying within the blue sky. Visual communication is so important in butterflies since it allows one to defend or hide itself, or even find their rival.

Chemical Communication

Chemical communication can be described as the use of odorants or other substances to transmit information between two individuals and is omnipresent in sexual communication in the majority of living organisms (Johansson 2007). Pheromones are typically the chemicals released and are involved in information exchange between species. Evidence of pheromones as indicators of mate quality and assessment can be broken down into levels. Those levels being species recognition, mate recognition, and mate assessment (Johansson 2007). Sometimes colored butterflies have issues distinguishing one another by sight alone, so chemicals are crucial for them to find potential mates.

“Signaling by adult butterflies serves two major functions: protection and intraspecific communication” (Vane-Wright 1993). The most common signaling method in a butterfly’s intraspecific communication includes the use of chemical signaling. Butterflies are often seen chasing after the wrong species, the same sex, or anything that resembles another butterfly to mate with, so they often release pheromones. Mainly males have complex exocrine glands to release pheromones and often release these pheromones in an attempt to attract a female mate (Myers 1972). Chemicals released by butterflies not only convey species and sex but can also display age and mating status (Vane-Wright 1993).

Not only do butterflies release the pheromones for courtship, they also use pheromones to repel other males from a butterfly that was recently mated. During mating, an anti-aphrodisiac pheromone is transferred to the female which decreases her attractiveness and helps fend off male competition and increases the time the female has to lay eggs (Mozuraitis 2019). Unfortunately, the use of an anti-aphrodisiac pheromone is susceptible to interception by potential predators. Parasitic wasps can eavesdrop on the intraspecific chemical communications and when they detect this pheromone, they follow her to her egg-laying site and “parasitize” the freshly laid eggs (Fatouros 2005).

The main uses for chemical communication are for identifying species and sex for mating opportunities, making it a very important component in communication. “Chemical stimuli and behavior patterns have more species cues and are important for species identification,” (Myers 1972). Some drawbacks for chemical communication is that “after a proper sequence of visual, tactile, and chemical stimuli, the male butterfly would attempt to mate with any object that was substituted for the female” (Myers 1972). A study by Lederer (1970) on the species Limenitis Camilla shows a male trying to mate with a dummy female butterfly. Even when the dummy began to fall apart, the male was still determined to copulate. Chemical communication plays the main role in reproduction but has its drawbacks. Unfortunately, many studies haven’t been done for butterflies and their capabilities of the chemicals they release. Moths typically receive more attention from chemists (Myers 1972).

Effective Communication

Butterflies are unique in their ability to communicate through visual, chemical, auditory, and other methods. This poses the question of which form of communication is the most effective for butterflies? While each form of communication is used differently, butterflies thrive by communicating visually in ways that attract mates through color signaling and pattern design. This form of communication allows us to gain a further understanding of how these butterflies utilize their appearance for successful mating and attraction.

Since butterflies’ wings are very visible, their wings serve several functions that are crucial to their ability to communicate. The patterns on their wings are able to function as more

than just aesthetic purposes. The function of their wing coloration is important for survival, but also those colors are important for communication and their involvement in sexual selection. The spectral range of butterflies is the broadest visible spectrum known in the animal kingdom (Silberglied 1979). This is especially useful during courtship. Courtship involves multiple forms of communication (ie; visual, chemical, etc.), however visual communication plays a primary role in is. Visual stimuli from females is what ultimately draws in males to seek out a mate. The color of these females is one of their most important qualities, as the males are not as interested in their shape but rather their attractiveness. Once the butterflies are drawn to their appearance they proceed to communicate with olfactory messages. After this, they continue with more visual cues used to deem the mate worthy. These cues involve different types of flight in females for the male to see and express their interest. Expressing their disinterest involves projecting visual cues known as ‘rejection postures’ which lets the male understand the female does not want to mate (Silberglied 1984). While specific colors of the females can be used to attract males, some colors may also be a deterrent to males in which they avoid those particular females. Research has found with Pieris bryoniae that yellow females are deemed less attractive than white females. It is also concluded that in Argynnis paphia, darker females were not as attractive to their male counterparts. Every butterfly species differs in which colors they are more drawn to for a mate, but overall wing coloration plays a huge role in visual cues during sexual selection.

The ultraviolet colors present in the wing patterns of butterflies are important for species recognition. This color influences both intraspecific and interspecific communication through mimicry, crypsis, and species recognition. In the Brunton 1995 study, they concluded that the UV reflectance levels of butterflies are important in mate recognition. Different species are represented through different UV patterns and coloration, so this identification through their UV reflectance is crucial for communication. Butterflies are able to successfully discriminate colors through a wide range on their visible spectrum, despite differences in light and contrast. As they are able to detect various levels of coloration, they use color and UV levels to identify and possibly seek out their mates through sexual selection. Overall, the variation in UV reflectance in male Pierid butterflies is influenced by mate choice between males and females (Brunton 1995). By assessing how the patterns and coloration of butterfly wings impacts their success in sexual selection, we are able to see how this will play a role in the evolutionary processes of butterflies in the future and further influence their behavior in communication.

Conclusion

While butterflies are not as popular of a subject when studying communication, it is important to understand the ways they communicate. In-depth research on their communication helps us gain a better understanding of their behavior and why they act the way they do. This research can reveal patterns of migration, sexual selection, courtship behavior, and other responses to their environments to shape future research on the species. We looked into the various forms of communication in butterflies, and evaluated how each form is unique to them. Starting with sound communication, we found that butterflies utilize clicking sounds to express feelings in instances of aggression and territoriality (Lockette 2004 par. 2). We also found butterflies that have ears attached to the top of their wings. These ears aid the butterflies in communicating using vibrational methods in their wings and allow them to hear and process auditory signals better. Using chemical communication, butterflies release pheromones to assist with courtship, and use chemical stimuli as cues used for identifying others (Johansson 2007). In visual communication, butterflies express visuals through their coloring in mating rituals, courtship, and predatory instances. The pigmentation of their wings allows for identifying mates and predators. Each of these forms of communication is uniquely utilized, as they each have their own specific purpose. However, visual communication could be considered the most effective form of communication within butterflies. This is because their appearance in their wing design and UV pigmentation aid them in successfully communicating with mates, as well as allowing them to identify others easier (Silberglied 1979). Since butterflies are able to discriminate colors on such a wide range of the visual spectrum, visual cues found in wing patterns and UV pigmentations are important indicators in sexual selection. Butterfly communication is a complex concept that involves a variety of forms. Butterflies utilize each of these forms as each one serves a different purpose and motive when communicating. This study allowed us to dive deeper into the world of communication for butterflies, and reveal how each form of communication is unique to their species and how it's used. Further research could find patterns in this behavior and see how it influences behavior in other areas. One example of further research could include finding out how these forms of communications during seuxal selection influences their migration patterns. By gaining a better understanding of the reasons for their choice in communication methods and actions, we can shape further studies and have more knowledge about their communication patterns influencing their behavior and the ecosystems that they inhabit.

Citations:

1. Barbero, F., Thomas, J. A., Bonelli, S., Balletto, E., Schönrogge, K. (2009). Queen Ants Make Distinctive Sounds That Are Mimicked by a Butterfly Social Parasite. Science Magazine, 323 (5915), 782-785. doi:10.1126/science.1163583

2. Brunton, C. F., & Majerus, M. E. (1995, May 22). Ultraviolet colours in butterflies: intra- or inter-specific communication? The Royal Society, 260(1358). https://www.jstor.org/stable/50073

3. Fatouros, N. E., Huigens, M. E., Loon, J. J., Dicke, M., & Hilker, M. (2005). Butterfly anti-aphrodisiac lures parasitic wasps. Nature, 433 (7027), 704-704. doi:10.1038/433704a

4. Johansson, B. G., & Jones, T. M. (2007). The role of chemical communication in mate choice. Biological Reviews, 82(2), 265-289. doi:10.1111/j.1469-185x.2007.00009.x

5. Korpella, R. (2018). What do Butterflies do for the Environment? Sciencing. https://sciencing.com/what-do-butterflies-do-environment-4580181.html

6. Lockette, T. (2004). Butterflies Can "Talk," UF Research Suggests. University of Florida. https://news.ufl.edu/archive/2004/07/butterflies-can-talk-uf-research-suggests-1.html

7. Michio Imafuku, Yukihiro Hirose, Tsuyoshi Takeuchi. (2002) Wing Colors of Chrysozephyrus Butterflies: Ultraviolet Reflection by Males. Zoologic Science, 19(2), 175-183 (2002). doi.org/10.21o8/rsj.19.175

8. Mozuraitis, R., Murtazina, R., Zurita, J., Pei, Y., Ilag, L., Wiklund, C., & Karlson, A. K. (2019). Anti-aphrodisiac pheromone, a renewable signal in adult butterflies. Scientific Reports, 9(1). doi:10.1038/s41598-019-50838-1

9. Myers, J. (1972). Pheromones and Courtship Behavior in Butterflies. American Zoologist, 12(3), 545-551. doi:10.1093/icb/12.3.545

10. Robert E. Silberglied & Orley R. Taylor Jr. (1978) Ultraviolet reflection and its behavioral role in the courtship. Behavioral Ecology and Sociobiology, 203-243 (1978). doi.org/10.1007/BF00296311

11. Silberglied, R. E. (1984). Visual communication and sexual selection among butterflies. Symposium of the Royal Entomological Society of London, 11, 207-223. ISSN:0080-4363

12. Travassos, M. A., Pierce, N. E. (1999). Acoustics, context and function of vibrational signalling in a lycaenid butterfly–ant mutualism. Museum of Comparative Zoology, Harvard University, 60 (1), 13-26. doi: 10.1006/anbe.1999.1364

13. Vane-Wight, R., & Boppré, M. (1993). Visual and chemical signalling in butterflies: Functional and phylogenetic perspectives. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 340(1292), 197-205. doi:10.1098/rstb.1993.0058

14. Yong, E. (2018). The Butterflies That Hear With Their Wings. The Atlantic. https://www.theatlantic.com/science/archive/2018/10/butterflies-hear-their-wings/573193/