The Buzz on Insect Sound

Anybody who has walked outside on a hot summer day and heard the cacophonous ticks, rattles and clicks of insect calls could imagine that there must be something being communicated in all that clatter. While insects produce sounds through their normal activities, such as the buzz of wings in flight or mandibles chewing, often specific behaviors produce sounds that signal a variety of information to the surrounding area. Insects can create sounds through various methods whether they be stridulation (rubbing the body, as in cricket and grasshopper calls), percussion, vibration, click mechanisms or air expulsion. In fact, the level of sophistication in these sounds can be rather surprising.

Waggle dance, describing the direction of a food source to other members of a colony (Image: Wikimedia Commons, CC BY-SA 3.0)

Take for instance the way in which a honeybee (Apis mellifera) forager is able to describe the direction, distance and aspects of the quality of found food sources to other members of the hive based on the sounds, vibrations and length/direction of its “waggle dance”.

Chorthippus parallelus, meadow grasshopper (Image: Peter O’Connor, CC BY-SA 2.0)

 

Many insect sounds often serve as signals to other members of the same species, as in mating calls. The purpose of the calls, besides providing location, is to relay information regarding the sender’s readiness/quality as a mate. Female fruit flies tend to prefer males that produce short song pulses with high carrier frequency. These high frequency pulses have been shown to positively correlate with the survival rate of offspring. Males announcing their location to potential female mates can also serve the purpose of telling other males where they are not welcome. However, in some species of bush crickets, cicadas and grasshoppers, males have a habit of aggregating in large groups and producing sounds in a chorus. By gathering together, these males can increase the effective range of their calls and decrease the individual chance of predation.

Ridges on the inside of the hind femur produce the grasshopper song as the legs are rubbed against hard forewings (image: Gilles San Martin, CC BY-SA 2.0)

While many kinds of sound are used for interspecific communication, some sounds exist to signal to other animals. Startle sounds are a kind of acoustic produced when insects try to confuse predators. The Peacock butterfly (Inachis io) generates an ultrasonic click that confuses the ability of bat predators to echolocate their prey. Mating calls can also be exploited by crafty mimics. An Australian bush cricket (Chlorobalius leucoviridis) is able to imitate species-specific responses of female cicadas to male mating calls. As the unfortunate suitor hears the correct sound response to know it is time to seek his lady, he finds himself on a someone’s dinner plate instead. Mutualistic relationships benefit from sound communication as well. Some insects, such as treehoppers (Publilia concava), develop in association with tending ants. The ants protect the treehoppers from predators while harvesting the sugary excretions (honeydew) of these homopterans. When a treehopper is threatened, the insect produces a specific vibration that travels through substrates and rouses the ants as well as any alarm call.

Treehopper nymphs being tended by ants (image: Pavel Kirillov, CC BY-SA 2.0)

The full diversity and complexity of communication through sound and vibration that insects employ is quite staggering. As researchers seeks to unravel these intricacies, evidence is being compiled that humans are effecting the arthropod world with our own noise pollution. Anthropogenic noise can impair communication between insects, distorting their ability to detect prey and predators or successfully find mates. In a recent article published in Ecology & Evolution, a group of scientists sought to investigate how the presence of broadband noise (sound that is distributed widely across audible ranges) produced by natural gas extractors influenced the surrounding arthropod communities.

Natural gas extraction site (image: anita_starzycka, CC0 Public Domain)

The researchers set up their experiment in the San Juan Basin of New Mexico, the second largest gas basin in the United States. This area has seen quite a lot of anthropogenic disturbance since the discovery of natural gas there in 1921. By placing pitfall traps near well pads both with and without gas compressors, the researchers were able to compare how noise affected arthropods across 10 sites. The scientists found that various groups of arthropods responded to background noise in different ways. All but one group surveyed were less abundant at sites that had higher levels of noise or featured gas compressors. Oddly, collected insects of the leafhopper family Cicadellidae seemed to be more abundant at sites with high compressor and background noise. Possible explanations for this occurrence could be that the leafhoppers are attracted to the noise, with the compressors acting as a sensory trap. Another explanation is that the high levels of noise could deter bats due to their reliance on echolocation, with the high noise level acting as a predator shield. Fortunately, the results of the study showed that community turnover was not occurring at either family or genus level, but the researchers put forth the idea that finer scale measurements and more collections were necessary to determine if species composition was changing.

One thing is for certain: the response to noise pollution in an arthropod group is unique to that group’s evolution and more research is needed to deduce what kind of adverse effect, if any, humans are having on these communities. The potential for species to be deterred from an area can vast unforeseen consequences. Arthropods serve a multitude of ecosystem functions, acting as pollinators, seed dispersers, herbivores, decomposers and prey. If the arthropod community changes drastically, the complex suite of interactions among prey, predators and mutualists may not survive the transition.

Literature Cited

Bunkley, J. P., McClure, C. J. W., Kawahara, A.W., Francis, C. D. and Barber, J. R. (2017), Anthropogenic Noise Changes Arthropod Abundances.” Ecology and Evolution 7, no. 9: 2977–85. doi:10.1002/ece3.2698.

Chapman, R. F. The Insects: Structure and Function. Cambridge University Press, 2012.

Further Reading:

Biology of Insect Songs

 

 

Star Wars and the Naming of Things

Wockia chewbacca, named after the famous furry companion of Han Solo (public domain).

Choosing a name for a newfound species or group of organisms can be a rather daunting task. It should be no surprise that taxonomists and other scientists are sometimes heavily influenced by literature and popular culture when deciding on the perfect name for their research subject. In fact, the website curioustaxonomy.net specializes in documenting the various instances in which scientific nomenclature (the system of names and naming) has honored famous figures in history, mythology and even important places. In honor of Star Wars Day, which is celebrated on May 4th to allow for a fantastic pun, a link to an article listing animals that were named after characters or creatures in the Star Wars universe can be found here. And, as always, May the Fourth be with you!

The pit made by the spider Aptostichus sarlacc recalled the one housing the monster from Return of the Jedi (photo, Marshal Hedin, 2009, CC BY 2.0)

Springing to Life

Crocus (photo: Dave Angelini, 2017, CC-BY-SA 4.0)

It’s late April and Spring has already reached many places, but it’s just getting to us here in Maine. In fact yesterday was one of the first really nice, warm days. There’s still snow in some spots, but everything is springing to life. People are coming out of their houses (putting away their skis) and getting back into the streets, parks and gardens. I spent a little time in my backyard yesterday, and I thought I’d give a tour of the insects I found crawling out from under rocks, literally and metaphorically.

Continue reading Springing to Life

Damselfly in distress: How sexual conflict shapes behavior

As the days grow longer and the temperature rises, the first vestiges of animal and plant life have begun to shake off the trappings of winter. Tender buds break open to reveal tightly packed profusions of floral color. Bird song greets the early morning sun and small animals stir from their dens. Insects begin to hatch from overwintered eggs or stretch their legs/wings after a long diapause. As the natural world awakens from winter quiescence, much of this activity takes the form of ensuring the continuation of the next generation.

Rambur’s forktail: Male (top) and brightly colored andromorph female (bottom). (photo by Bob Peterson CC BY 2.0)

In that spirit, let’s examine some surprising recent findings on the mating system of a damselfly, known as Ischnura ramburii, or Rambur’s forktail.  While much emphasis is placed on biodiversity in the sense of density of species on the planet, there is often just as much diversity exhibited in the way species approach the ubiquitous problems of life, such as resource acquisition and reproduction. Particularly, conflict between the sexes of a species can influence mating systems, speciation and population dynamics. A mating system is the collection of behaviors individuals in a species use during reproduction. A recent study, conducted by Dr. Eben Gering, looked into how a specific trait, male mimicry in females, evolved due to the unique pressures experienced by Rambur’s forktail damselfly.

Continue reading Damselfly in distress: How sexual conflict shapes behavior

Sporadic Spider Crickets

Cricket
Cricket, probably Ceuthophilus (photo by Thegreenj, CC BY-SA 3.0)

Spider crickets, camel crickets, cave crickets–whatever you call them, they scare the life out of me!

Spider crickets come from the family Rhaphidophoridae, and from a distance they look like spiders. If you take a closer look at one of them, you can see its long antennae, large hind legs, and shrimp-like body.

Spider crickets can often be found in caves or other cool, dark, and damp areas. However, you may have to watch out, because spider crickets can also be found in the basements of suburban houses, sewers, and even stacks of firewood. They shelter in dark areas because their vision is poor, and they rely on their antennae to feel around for food. The diet of a spider cricket consists of organic compost, but these creatures are also known to eat each other (cannibal crickets?).

When something is near, spider crickets bounce around rapidly with expectations of scaring away any potential enemies. I had a personal encounter with one bout a year ago. A few of these creatures took up residence in my mother’s house, which is back in Oklahoma. Nearly every time I went in the bathroom, I saw one start hopping around the room.

Though these creatures are intimidating, they are harmless. So, if you see one around…RUN! Well, you don’t have to run, but I will.

If you want to know more, check out this article from the Washington Post.

Wondering in Winter: Where did the bugs all go?

“Winter Scene in Victoria Park, London, Ontario.” (photo by Lisa Birtch, CC BY-SA 2.0, https://goo.gl/A65a6F)

Here in the Northern part of the US, the blustery winds of winter are well upon us. The cold climate forces us to bundle up in warm layers clothes if we choose to brave the frozen world outside our well-heated, insulated homes. With so much of our response to the cold being behavioral, the question may arise as to how other animals endure the harshest time of the year. Some of us may be familiar with the hibernation of other mammals, but how do the creatures that don’t produce their own body heat (ectotherms) manage to survive? Insects have the additional concern of losing heat rapidly due to their diminutive size and small surface area. Most insects, much like members of the plant kingdom, have to survive while remaining in thermal equilibrium with the frozen world outside.

Continue reading Wondering in Winter: Where did the bugs all go?

Is it a Groundhog or Woodchuck?

How much wood could a woodchuck chuck if a woodchuck could chuck wood? 

 While they are herbivores, Woodchucks, also known as Groundhogs, Land-Beavers, and Whistle-Pigs, prefer the same fruits and vegetables we eat at home. The amount of carrots, apples, beans, peas, and any flowers groundhogs consume adds up to about a 1/3 of their entire body weight, per day!

When they are not eating, woodchucks are probably burrowing, or using their long, sharp claws to dig. These are not your common holes though. Groundhogs are able to build connected multi-chamber burrows, sometimes they even make a bathroom. Located across North America in areas where woodlands meet open spaces, their fanciful homes are put to good use in the winter, when they hibernate. Continue reading Is it a Groundhog or Woodchuck?

What is a True Fly?

Common housefly, Musca domestica (image: Wikimedia Commons, CC-BY-2.0)
Common housefly, Musca domestica (image: Wikimedia Commons, CC-BY-2.0)

Anything that is small, bug-like, and has wings is a fly, right? Wrong! There are only about 120,000 flies that belong to the order Diptera, or “true” flies.  Dipterans include not only commonly known flies such as houseflies and fruit flies, but also mosquitoes, midges, and craneflies.

These true flies have only one pair of wings. They are also characterized by containing a pair of balancing organs on the base of their wings, called halteres. Halteres vibrate during flight and help flies maintain their balance. Not all dipterans can fly, though. Some flies, such as parasites or those inhabiting islands and alpine areas, don’t have any wings.

The immature stage of flies are called maggots. Maggots absolutely love being in wet environments: most live in water or some other moist environment, such as rotting plant or animal tissue. Those that live in water often have some type of breathing tube or gills to obtain air. There are also some true flies out there that feed only on living plants or animals.

Haustellate mouthpart on a mosquito (Wikipedia, CC-BY-3.0)
Haustellate mouthpart on a mosquito (Wikipedia, CC-BY-3.0)

Adult flies have a wide range of habitat preferences and lifestyles. They can live anywhere on earth with the exception of Antarctica and extremely dry deserts.  Many true flies are found in environments such as hot springs, stagnant water, tree holes, and streams. As for obtaining food, most species have haustellate mouthparts,  which are long and tube-like, allowing flies to suck up food in liquid form.  These mouthparts are incredibly diverse, ranging from mouths that are adapted to lapping and those that can pierce through tissues of a host, such as mosquitoes and deer flies.

Fly (resembling a wasp) sitting on a flower (Image: Wikimedia Commons, public domain)
Fly (resembling a wasp) sitting on a flower (Image: Wikimedia Commons, public domain)

Many dipterans are beneficial to humans. Flies that visit flowers aid in the pollination of flowering plants and flies that feed on parasites help reduce pest species such as moth caterpillars, beetle grubs, and garden pests.  There are also flies that are harmful to humans. Some flies are able to transmit destructive diseases, such as malaria and yellow fever. The common house fly is a carrier of some harmful diseases, such as anthrax and typhoid fever.

So, next time you think you see a fly, try to see if it has two wings and halteres attached to it!

 

 

The Death Watch Beetle

You would probably find the deathwatch beetle in a house like this...(Image: Wikimedia Commons, CC-BY-SA-2.0)
You would probably find the deathwatch beetle in a house like this…(Image: Wikimedia Commons, CC-BY-SA-2.0)

If you hear a strange ticking noise at night, don’t be too alarmed! It’s not some ghost trying to haunt you…it’s likely the deathwatch beetle  hanging out in your old wooden furniture! Continue reading The Death Watch Beetle

Urban Beekeeping in the Big Apple

 

A honey bee in Toronto (Image: Wikipedia, CC 4.0)
A honey bee in Toronto (Image: Wikipedia, CC by 4.0)

As the world and its cities continue to grow (over half of the world’s population lives in cities!), more and more urban areas are making it possible to raise and care for honey bees in city environments. In 2010, beekeeping became legal in New York City- a great step in advancing the city toward more environmental (and economic!) benefits. Continue reading Urban Beekeeping in the Big Apple

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