Cricket Biology Archives

Okay, so this might not seem to be  about “cricket biology”, but in many ways it is related!  After all, the reason that cricket protein works as an alternative protein for humans (yes I said humans!), comes down to the biological make up of the insect.

chapul cricket bar

The world’s first cricket bar…

1/2013

A new type of energy bar is being sold in the United States now.  Chapul Bars are the first of their kind in world. What makes them so unique?  They contain a special kind of flour that is made primarily with ground up crickets.  :-0.

Pat Crowley, the founder of Chapul Bars, was initially inspired to start the business because of environmental issues.  Troubled by the environmental consequences of the over-consumption of water and grains in the U.S, Pat began seeking a lasting solution.  It was not until he heard Dr.Marcel Dicke’s bug-eating lecture, that he seriously considered insects as an answer to the problem.

It was then that he discovered that insects are 10 times more efficient at  converting grains into protein, than cows and other farm animals.  Additionally, crickets are low in fat and high in omega-3 fatty acids. What better ingredient for a healthy energy bar?

Pat says that since 80% of the world’s population already consumes insects as a regular part of their diet, why not North America and Europe too?   It is foreseeable that in a few years, insects may be as common of a food as sushi in the United States. Up until 1975, raw fish was considered gross by most Americans. Today there are sushi restaurants in almost every city.  This proves that it is very possible to change the culture and psychology of a society.

Chapul Bars are currently available in 2 different  flavors: Chaco and Thai. The Chaco flavor is the original one the company started with. It contains dates, chocolate, and peanuts.  The Thai flavor is a blend of coconut, ginger, lime, dates, almond butter, and cashews.  Chapul Bars have been described as being deliciously sweet and chewy.  If we didn’t tell you they had insect in them, you’d probably never guess!

So where can you buy them?   The easiest way is to order them online from www.chapul.com.  If you’d prefer to buy them in a store, go to the site and read the list of where they can be bought locally.

2013

Exactly how certain insects form germ cells, the foundational cells for eggs and sperm, has always been a scientific mystery – until now. Biologists from Harvard University have made a groundbreaking detection that is forcing the scientific community to rethink the evolutionary origins of a gene called “oskar”. Previously, the oskar gene was thought to have been necessary for the germination process.

Harvard’s team of researchers were led in a study by Cassandra Extavour, the Associate Professor of Organismic Evolutionary Biology. They found a cricket to contain a strain of the oskar gene which has always only been observed in more evolved insects such as fruit flies. Crickets are considered “lower insects” and were never known to contain this gene, so scientists assumed that the gene must have evolved later on. But now, this new finding suggests that the oskar gene actually developed much sooner than biologists believed.

Another astonishing finding of this study: The oskar gene in the crickets was not present in germ cells, but in neural stem cells known as neuroblasts. Throughout history, the oskar gene has only been noted as a component for germ cells. Scientists understood for decades that fruit flies and other “higher insects” use a process to put the oskar gene into their eggs before laying them. Thanks to the Harvard biologist’s study, a new hypothesis was born. The gene must have originally been responsible for the nervous system rather than the reproductive system. Professor Extavour’s team came up with the new hypothesis after seeing that the crickets’ nervous systems malfunctioned when the gene was removed.

“Our argument is basically that in the last common ancestor of insects, the ancestral role for oskar was most likely in wiring the nervous system,” said Professor Extavour. “Somewhere along the line, it got co-opted into this germ line pathway, and eventually rose to prominence in the hierarchy of genes that control germ cell formation.”

Not only does this new information automatically count former theories as false, but it also brings out the necessity of seeing past the science community’s traditionally respected models of research. If Extavour and her team of researchers had just accepted the predetermined organism models, they never would have come to this astounding truth.

Cassandra Extavour, the leader of this study, is also the director of the National Science Foundation’s Evo-Devo-Eco Network (EDEN) initiative. The foundation provides funding for scientists who choose to work outside conventional science models.

December 2012

Ever look at a cricket and think, “Oooh looks just like that dolphin we saw at Sea World”?

I bet you’d agree that’s an unlikely scenario.

However, according to a new study conducted by a team of international researchers including biologists from the University of Auckland (New Zealand), representatives from Plant & Food Research (New Zealand), and engineers from the University of Strathclyde, crickets have more in common with whales and dolphins than you’d imagine.

Crickets, katydids, and other related insects in the scientific order of Orthoptera, have been found to share the same hearing / audio system component as dolphins and other whales.  This is astounding news because before this study, it was long believed that toothed whales were the only creatures in the world to possess this particular hearing component. This component is a lipid (A.K.A compound of fats and oils).

For the first time in history, it has been proven that toothed whales are not the only creatures to utilize the specific lipid compound for hearing.  And who would have ever thought that a cricket  would be the one to defy this preconceived notion?

The initial research was done on the Auckland Tree Weta, but the lipid is supposedly present in other insects in the cricket/katydid biological class as well.  Using ultrasound technology from the University of Strathclyde’s Ultrasound Engineering dept., the scientists were able to observe liquid inside the insect’s sound cavity. This liquid was previously thought to be nothing more than the insect version of blood.  Yet, the researchers found that the liquid tested chemically as a new lipid, thus proving old theories wrong.

Dr.James Windmill (University of Strathclyde) said,”The discovery is interesting as previously only toothed whales were known to use this hearing system component, the lipid. There are many similarities in the use of lipids to amplify the sounds and help both animal groups to hear. We don’t know why animals who are so far apart in evolutionary terms have this similarity, but it opens up the possibility that others may use the same system component.”

The scientists also came across an organ which they believe is responsible for producing the lipid. They may not have ever noticed it if it were not for their fine-tuned method for analyzing the 3-dimensional ultrasound images.

Dr.Kate Lomas (University of Auckland) said, “The ear is surprisingly delicate so we had to modify how we looked at its structure and in doing so we discovered this tiny organ.”

The full details and results of the project are published in the PLOS ONE Online Journal.

Have you ever stuck feeder crickets in the freezer for storage, only to find that they were still alive when you took them out?   Yikes!  Sometimes it is not very obvious, because their movements slow down significantly from the cold.  However, the slightest twitch can indicate that the cricket is not dead yet, but living in a frozen coma-like state.  How is that even possible?  Well, the coma-like state is sort of similar to hibernation in mammals.  In insects, it takes a certain amount of time for death to be induced by low temperatures.

A research team of biologists at Western University (Canada), has discovered precisely how field crickets recover from a bout of extremely cold temperatures.

western university cricket

Photo credit: Western University.

Their findings were published on November 28th 2012 by Proceedings of the National Academy of Sciences (PNAS).  The study was led by PhD  student Heath MacMillan, under Professor Brent Sinclair at Western University.

MacMillan’s team found that crickets recover from chill-coma by replenishing salt and water imbalances in the body.  This cannot happen successfully if the insect is left frozen for an extended period of time.  Otherwise, the metabolism will just slow until it stops. Yet, if the cricket is given a brief moment of normal temperatures, the recovery process begins.

MacMillan says, “Insects lose the ability to maintain proper water balance in the cold, so when they are chilled, water and sodium move from the insect blood, called hemolymph, into their gut. This is bad for the insect because it concentrates potassium in the blood that remains, which leaves muscles unable to function.”

Once a live frozen cricket is taken into normal room temperature, its body begins restoring potassium concentration to the right levels.  Often just a few minutes after its brought to normal temperature, the cricket is able to move its limbs again.

“This work is significant because it allows us to identify the mechanisms that drive insect movement at low temperatures. This will lead to a better understanding of the biology of pest and beneficial insects during cold snaps at any time of year, and maybe help us to predict how different insects respond to changing conditions. This will also help us manage agriculture and biodiversity in a changing climate.” says Professor Sinclair.

So how can this info help reptile and amphibian pet owners?

The next time you decide to freeze your pet’s crickets,  remember that a few hours in the freezer won’t necessarily kill them. Those who need some extra storage space for unused crickets may opt to refrigerate them, rather than freeze them. That way, you can keep them alive for a couple days to a week.  Although their bodies will shut down, they’ll come back to life fairly shortly after you take them out of the refrigerator. They’ll be easier to handle and feed this way too, as their movements shall be much slower!

November 17th 2012

Though we have known for a long time that the cricket’s auditory system is complex, scientists have never quite understood the inner connections of that system.  A new discovery by researchers at the University of Bristol and the University of Lincoln reveals that cricket ears, while physically structured differently, actually function extremely similar to human ears.  What’s even more exciting, is that scholars expect this new information to lead to technological advancement in the medical field, especially pertaining to assisted hearing devices.

The study, which was published in yesterday’s U.S Science journal, was done specifically on a type of bush cricket (A.K.A katydid) known as the South American Bush Cricket. Bush crickets actually have some of the smallest ears in all the animal kingdom.  Researchers Fernando Montealegre-Z, Thorin Jonsson, Kate Robson-Brown, Matthew Postles, and Daniel Robert, were able to study this species ears by placing the insect’s legs into a micro CT scanner. While observing the bush cricket’s ear tube structure, they found a completely new organ: the insect version of the human “middle ear”.

“We discovered a novel structure that constitutes the key element in hearing in these insects, which had not been considered in previous work. The organ is a fluid-filled vesicle, which we have named the ‘Auditory Vesicle’,” Researcher Dr Fernando Montealegre-Z said.

In humans and other mammals, the middle ear is responsible for converting sound into liquid vibrations which are then translated by a third ear component before being interpreted by the brain.

However, not only did these scientists discover the cricket equivalent to the human middle ear, but also the cricket equivalent to that third component that analyzes the vibrations detected in the middle ear.  In humans, this correlates to our three ear bones. Dr. Montealegre says the katydid’s version is called a “tympanal plate”. From the outside, this tympanal plate seems to be merely a part of the bug’s exoskeleton.  Yet, the university pioneers used a Laser Doppler Vibrometer to witness the tympanal plate vibrating in accordance with the eardrum.

Daniel Robert, one of the head authors of this study, says that we can learn to replicate these miniature microphones that nature has designed.  By closely studying the tiny cricket ear mechanisms, bio-engineers may be able to dramatically improve hearing aids, medical imaging, and many other technologies in the near future.

Unlike humans, insects do not have lungs. Their respiratory system is not coordinated to a circulatory system involving blood pumped with oxygen and delivered through out the body. Nor do they breathe though only a couple select openings like a mouth or nostrils. Instead, crickets and other insects take oxygen in via several spiracles (openings) on the sides of their bodies. (This is why crickets drown so easily if they are kept in an enclosure with a water bowl.) Oxygen enters through the spiracles and is spread through out a system of internal tubes called “tracheae”.

Until the year 2003, scientists figured that all insects exchange oxygen slowly through the tracheae tubes. Advanced technology, however, has made it possible for researchers to get an inside look at the breathing mechanisms insects. We now know that crickets, beetles, ants, roaches, and dragonflies breathe in a manner that is very similar to humans, despite the insects not having lungs.

(By the way,  did you know that crickets hear the same way as dolphins?)

A study, led by zoologist Mark Westneat, made the front cover of Science magazine because it was the first time that scientists ever watched the breathing function of living insects.  To do this, they used the help of a revolutionary piece of technology called a “synchrotron”. The synchrotron is a particle accelerator that can accelerate electrons almost to the speed of light! This makes it capable of producing x-rays incredibly more powerful than conventional sources.  Using this machine, the researchers watched live video footage of breathing crickets and discovered that the tracheae compress and expand in a similar way that human lungs compress and expand. The breathing cycles can be as fast as one cycle per second which is about the same oxygen exchange rate as a human doing moderate exercise.

Breathing X-Ray photo (BBC News)

An insect’s tracheae compressing and expanding, much like lungs.

Another cool component of the technology is the way the images can be enhanced to emphasize edges so that the outline of tracheae is clearly defined. This makes much easier for biologists to tell what is happening in the video footage and images. As you can see from the above example, the photos sort of look like penciled sketches.

“This is the first time anyone has applied this technology to study living insects,” says Wah-Keat Lee, a physicist at the Argonne National Laboratory. ~

Crickets are cooler than you thought eh?   Scientists are even making hearing aids based on crickets now!

Be sure to check out our Cricket Anatomy page for color diagrams and more facts pertaining to crickets.

It is widely known in the herpetology community that captive-bred reptiles and amphibians, which depend on crickets for a staple of their diet, commonly suffer from nutritional deficiencies that are unheard of in their wild relatives.  Although these deficiencies can be prevented by adding variety to pet diets and incorporating adequate gut loading techniques, pet owners are often limited in their access to various species of feeder insects.  For example,  in the United States, there are currently only two species of cricket available for purchase, and the industry tends to lean toward just one.  Other parts of the world seem to offer more diversity.  Regardless, there has never been much research done to give insight unto which particular species of cricket best absorbs and retains nutrients.

Recently, however, the Zoo Biology journal published a study that addresses this subject.  The study revealed which cricket breed is best at retaining carotenoids, and which type of food best absorbs carotenoids in the cricket’s body.  Carotenoids are pigments that come from plants and act as antioxidants.  In humans, they’re believed to improve the immune system, and are credited with much of the health benefits that come from eating fruits and vegetables.

The study tested three types of cricket feed / ingredients used in gut loads:

1.) Wheat germ

2.) Fish flakes

3.)  Fresh fruits & veggies

And three different species of crickets:

1.) Acheta Domesticus  – most commonly used for pet food in the U.S., native to Asia.

2.) Gryllodes sigillatus - not very frequent in the pet trade, but interesting to consider.

3.) Gryllus bimaculatus – commonly used by European and Asian pet keepers.

Study Findings:
The researchers discovered that Gryllus bimaculatus (black crickets) retained carotenoids much better than the other two species of crickets!  Also, carotenoid levels were higher for all tested species that consumed fruits and veggies.  The fish flakes diet brought about intermediate carotenoid levels, while crickets who were fed wheat germ had the lowest levels of carotenoids.  However, caretonoid levels decreased over time in all crickets.

So what does this mean?

These findings indicate that reptile and amphibian owners can pass the most nutrition to their pets by feeding them Gryllus bimaculatus crickets that have been gut loaded primarily with fruits and vegetables.  If this species is unavailable in your part of the world, you can still boost nutrition by including fresh fruits and vegetables in your gut loads and cricket feeds.  The fact that carotenoid levels decrease as time passes further enhances the importance of using gut loaded crickets within 24-48 hours.

For some people, the question of whether insects can feel pain or not may render a “So what, who cares?” response.  Still, others may be curious  about this topic.  Any time hundreds of insects are housed together, like in cricket breeding setups, there are bound to be some critters that lose appendages or succumb to cannibalism.  It can appear ugly from the outside and may cause one to wonder how these experiences are perceived from the cricket’s perspective.  Are crickets capable of feeling pain?

Crickets, like other insects, do have a nervous system that consists of dendrites and ganglia.  As far as the scientific community is concerned, the jury is still out on whether or not an insect can feel pain.  Most insects do not contain nociceptors,  the cells responsible for transmitting pain as we know it in humans and animals.  However, in 2003, a study indicated that fruit flies are indeed equipped with nociceptors and capable of feeling pain.  Observations of other insects seem to indicate otherwise though.  In multiple experiments, caterpillars, locusts, and wasps continue to eat and mate, right up to their moment of death without any observable change of behavior.  A locust continues feeding as though nothing is happening even as a praying mantis devours its hindquarters.  This leads scientists to conclude that these insects do not feel pain the way that we do.  Yet, it is worth mentioning that just because an insect does not respond the way a vertebrate would, does not mean that the insect is not experiencing pain or suffering.

Surprisingly, there have not yet been any specific pain studies published about crickets.  It would seem that since crickets are related to locusts, they would probably respond in a similar fashion.  It may be unlikely that crickets feel pain, but there is really no way to know for sure without becoming a cricket.  It only makes sense to do our best to treat these feeder insects with respect and consideration.

When your reptile pet gobbles up a cricket, the cricket most likely dies instantly as its body is crushed in the reptile’s mouth.  That is just a natural part of the life cycle.  Unnecessary cruelty, on the other hand, should not be encouraged or excused.

Have you ever wanted to eat a cricket though?  You can now eat them as food in the U.S., in the form of cricket protein bars.

The auditory system of the common field cricket is amazing. Sound and the ability to hear is important for both male crickets and female crickets.  The males must be able to hear their own chirp and the chirps of rival males, while females need directional hearing to properly respond to the male of their choice.  In both males and females, the strong hearing ability allows crickets to dodge bats by fleeing in the opposite direction of the echolocation calls. It should come as no surprise that crickets have finely tuned auditory receptors that are even capable of regenerating themselves.  Yet, it still seems unbelievable that such a thing would be possible for a mere insect.

A cricket’s eardrums are located on the front of its front knees and connected with tracheal tubes.  The ear, by itself, cannot sense the direction of a sound source.  When functioning as a whole with the intact audio system, however, directional hearing is possible and occurs by a comparison of pressure fluctuations between the left and right ear.

Researchers at the University of Bowdoin have even proven how important it is for crickets to have both ears in order to sense direction.  They hooked up a special spherical treadmill and attached a cricket to it. As the cricket walks on the treadmill, they can measure its responses to different sound stimuli.  For part of the experiment, they removed one ear from each of their crickets.  Over time, they discovered that the crickets began growing a new ear.  Dendrites had developed and reached across to communicate to the ear on the other side, thus proving the significance of double-ear communication for cricket directional hearing.

A Cricket on a Treadmill:

The special cricket treadmill maps out the coordinates of the cricket’s steps so that the students can observe the precise direction the cricket moves when different types of sounds are played.

Cricket Paralysis Viruses are small RNA-containing or DNA-containing viruses that are very similar to the picornaviruses affecting honeybees, flies, and moths. Strains of these viruses have been observed in New Zealand, Australia, the United Kingdom, Indonesia, and the United States of America. These viruses cannot infect or harm humans and animals.

The original Cricket Paralysis Virus is an RNA virus that was first found in a few species of Australian crickets a number of years ago. Since then, there have been many more strains of “cricket paralysis virus” observed in various species of crickets.  The latest infections are a different type of virus than the original CrPV.

The most recent outbreak occurred first in the European house cricket, and then spread to the United States and Canada. In 2002, Europe’s reptile pet and zoo industry suffered a catastrophic wipeout of crickets. Later, in 2010, the virus began its destruction across North American cricket farms.

The new “cricket paralysis virus” is a DNA-containing, Acheta domesticus densovirus. It only affects this one particular species known as the common house cricket. Unfortunately, at the time that the virus struck, all of the largest cricket farms in North America and Europe were raising Acheta domesticus crickets. Many cricket farmers went bankrupt and were forced out of business.  At least 5 out of the 10 major U.S. cricket farms had to close their doors.

According to an article in the Kalamazoo Gazette, Bob Eldredge of Top Hat Cricket Farm said:

“It moved through this factory like nothing we’ve ever seen before…We were seeing dead crickets everywhere within a matter of weeks. We dumped 30 million crickets we had right in the garbage.”

Top Hat Cricket Farm closed up shop in 2010 after attempting to fight the virus with no success. They decided to rebuild the business by switching to a different species of crickets. The difficult part about switching to a new species is that the U.S. requires approval and the attainment of a permit. Also, before the virus breakout, Acheta domesticus was the only USDA approved commercial cricket breed. As a response to the breakout, farmers were able to receive a permit to breed and sell Gryllus assimilis. Gryllus assimilis is a type of brown cricket that is very similar to the popular house crickets, but is immune to the densovirus.  In August of 2011, Top Hat obtained their commercial permit for the new breed. Their website states that they will be up and running again in the summer of 2012.

Just like Top Hat, many other farmers made the decision to switch to a different breed of cricket. Sadly, some of the farms were unable to recover. Elizabeth Payne, of Lucky Lure Cricket Farm (Florida), ironically was not very lucky and had to declare bankruptcy as a result of the cricket wipeout.  Take a look at our brief interview with Michelle from The Cricket Farm, another cricket farmer who lost business due to the virus.

If anything, the disastrous affects of the cricket virus teach us all an important lesson. We need to be prepared, ready to adapt, and not too dependent on any one way of operating.  Farmers need to be as aware as possible of alternative cricket breeds, in case a similar virus should strike again.  Pet owners and pet shop owners may want to learn to raise their own crickets.  This way, nobody has to panic if a major supplier is suddenly out of crickets. Permits may be required for the commercial sale of crickets, but not necessarily for hobbyists who want to breed crickets for their own use at home.

Symptoms of the Acheta domesticus, “cricket paralysis virus”:
Crickets will flip over on their backs, paralyzed, and die.

Note: If you receive a shipment of crickets displaying the above behavior, be sure to report it to whomever you bought the crickets from.

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