BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: Insects

A New Mosquitoes Exterminator: CRISPR

Mosquitoes might be just pesky little insects that might start appearing again in a few months. They leave their saliva in your skin, and this causes an itchy bump. But in other parts of the world. Estimates report that mosquitoes have killed up to 52 billion people in history by spreading malaria, yellow fever, and dengue. It is currently killing 1 million people per year, even with advanced medicine and healthcare around the world. Doesn’t that horrifying statistic shock you? 

Aedes aegypti

A close shot of Aedes aegypti

To drastically lower this number, researchers took a smart approach and decided to eliminate the source of the problem. They decided to use CRISPR to genetically alter the male flies so that they become sterile.  Professor Craig Montell from UC Santa Barbara altered the gene of Aedes aegypti, the main type of mosquito that transmits dengue, yellow fever, Zika, etc. 

Previously, scientists just radiated and applied chemicals to sterilize male mosquitoes in hopes to alter their genes since “there are enough genes that affect fertility that one will likely be altered,” making them infertile. However, this would leave, many of the mosquitoes to be sick and die prematurely since other genes that don’t relate to fertility are also changed.

Using CRISPER/Cas9, researchers removed B2t, a gene that specifically affects male fertility in mosquitoes. Unlike in previous efforts, the sterile mosquitoes were completely healthy. 

This whole effort to sterilize insects is part of a greater method called the sterile insect technique (SIT). Scientists release way more sterile insects than there exist in the wild. The population will crash as females will not be mating with a lot of males that are capable of making offspring. A benefit of releasing males instead of females is that males feed on nectar, not blood,  so it will not cause major disturbance to communities.

To sexually reproduce, a sperm cell must meet an egg. Each gamete is a haploid that has a single set of chromosomes. The sperm and egg combine to produce a zygote making it a diploid with a complete set of chromosomes. If a male is sterile, then they are not able to produce or release their sperm, making it impossible for those insects to reproduce.

The effect of this technique is more effective after each cycle, so when you release the same amount of mosquitoes after 3 cycles, the population change will be way more drastic. A downside to this is that sterile male mosquitoes need to be reintroduced after they die off since they cannot pass on their mutated gene.

Although researchers have successfully identified a way to isolate the gene and remove it to make male mosquitoes fertile, they still needed to find the optimal ratio of lab mosquitoes to wild type to ensure that they do not wipe out the species in an area since that has dramatic effects on the whole ecosystem. The researchers conducted many trials and found that, in a week, a ratio of about “5 or 6 sterile males to one wild-type male” decreased female fertility by 50% while, a ratio of 15:1 suppressed female fertility to about 20%, where it leveled off. So depending on the situation, they now release the more precise amount. 

I think that this is one of the brilliant uses of CRISPR, and it only goes to show how far we can go if we master this technique. An ethics question that this research brings up is, do humans have the right to wipe out an entire species just because it is causing harm to humans?

Tiny Devils Take Down Gentle Giants all due to Climate Change!

File:Alce (Alces alces), Potter marsh, Alaska, Estados Unidos, 2017-08-22, DD 139.jpg

A innocent female moose, about to be attacked by an onset of terrible parasite in Northeast Canada.

Winter Ticks, not containing Lyme Disease or other Human-harming diseases, are rising exponentially in population throughout New England and Canada, all due to increasingly warmer and snow-free springs and later winters everywhere. As a result, an unlikely species in this region is being targeted by these tick epizootics, Moose, because ticks search for hosts in the fall and other warmer temperatures and stop once freezing weather and snow befalls the land. Yet, when these conditions occur much later, it gives these ticks more time to feast on peaceful animals, and also giving more time for female ticks to fall off its host and create tons more larvae, not making this issue any better. As these raisin sized parasites latch onto to these large creatures, draining so much blood at a time that they simply are unable to function anymore and weakly fall, succumbing to the environment, other predators, or even more ticks. But it’s not simply a few ticks, no, these moose can carry up to around 90,000 ticks! Because of this, there has been “an unprecedented 70 percent death rate of calves over a three-year period” according to a similar source from the University of New Hampshire. Plus, this problem has gotten so bad that now a threatened species in this region of British Columbia, the boreal Caribou, are being eaten alive as well!” If blood loss from heavy tick loads does not directly kill animals, it can make them susceptible to other health risks, Schwantje adds in the original source. “They have spent so much time scratching and chewing on themselves that they haven’t been feeding, so they are in poor body condition,” she says, even with tremendous hair loss that they become basically unrecognizable.

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An example of one of these detrimental winter ticks, a female engorged in size with blood and larvae, ready to reproduce .

But How Can This Be Stopped?

Currently, researchers are offering a multitude of solutions to help save these wonderful species from these terrifying parasites, as Swantje says that “They have huge cultural and nutritional value to our First Nations, And when moose forage in wetlands, they help release nutrients into the environment and make them available to other plants and organisms, studies have shown”, one solution can even be seen here. One possibility is to continuously treat half of the moose with anti-parasite gel and pills that make attached ticks drop from their bodies in order to isolate specifically what the ticks do and don’t do to harm these moose. The other possibility is a highly unlikely one, hunt the moose. Researcher Peter Pekins suggests that “issuing more moose-hunting permits in strategically selected areas” could essentially starve out the ticks in certain areas, yet it is argued that this would only benefit the environment short term, as the climate will continue to warm leading to the growth of more and more ticks.

Who know, if this isn’t stopped soon, ticks will continue to grow in population and maybe even take down us humans! Save the moose (and the caribou)!

Males to Become Obsolete?

“No study in the past [has described] a complete elimination of males,” claims Rebeca Rosengaus, an insect sociobiologist and behavioral ecologist at Northeastern University. Professor Rosengaus’ statement relates to the study by postdoctoral researcher Toshihisa Yashiro and Professor Nathan Lo on Japanese 

islands of Shikoku and Kyushu, where termites are evolved to reproduce strictly asexual with a population of only females. The primary question facing the researcher team faces is how does this advanced animal population reproduce without the necessity for their male counterparts? The termite subset of the cockroach family is not the first creature to do so as there are species of hymenopteran insects, both ants and bees, that have gone female.  Due to the recent discovery of the evolutionary change, researchers can only hypothesis on the breeding techniques of the all-female termite populations based on similar populations of bees and prior termite activity. In the strictly feminine bee colony, the label queen, which normally mates and holds a sperm-hoarding pouch within her body from males, reproduces by laying unfertilized eggs which only receives chromosomes from their mothers and hatch producing females with double copies of their mothers’ chromosomes at a far faster rate. These termites, however, also varied from their typical monogamous relationships and queen and king breeders to a queen driven society before in order to avoid inbreeding between fertile kings and their own offsprings. So while there are many suspicions on the reproduction of these highly evolved termites, the answer to how they evolved to such conditions are left unknown as the normal order of society is to maintain the health of a colony through sexual reproduction to protect against diseases and environmental changes. Such diseases are believed to be rather rare, however, on the islands of Shikoku and Kyushu, yet this concept is under-researched as of now. These females are surviving after this shift in sexual dependence approximately fourteen million years ago as their all-female band of soldiers are structured far more uniformly and have increased defensive efficiency. These females are not suffering by any means without their male counterparts. The Glyptotermes nakajima species are the underrated feminist heroes of our insect world despite being only a few millimeters long with soft, doughy bodies. What do you think will human males someday become obsolete? Is this the way the world is going or just a random phenomenon?

 

Amino Kassid

 

Source Article:

 https://www.sciencedaily.com/releases/2018/09/180925110051.htm

The Zombie Apocalypse is Coming! – Sort of…

Imagine a disease that, once it infects another organism, it completely takes control of their body and uses it for further infection and mutilation. This is exactly what is happening in the incredibly noisy (100 decibels to be exact) seasonal insects, named the periodical cicada (Magicicada sp.). However much you might like or absolutely hate these insects (like me), they unfortunately are suffering from a rampant parasitic fungus that is essentially taking control of these bugs and turning them into zombies. This zombie fungus is incredibly brutal to the cicadas, causing their almost-lifeless body to be driven around by this fungus, losing parts of their own body while gaining another cicadas head that becomes attached during forced copulation by the fungus to infect more cicadas. It is pretty much like “The Walking Dead” in the insect world, with cicadas being driven around by a parasite infecting others at a rapid speed with insect parts flying all over the place. 

This fungus, the Massospora cicadina, typically begins its infection on the insect when the cicada nymphs come to the surface after about 17 years of feeding off of plant roots underground. When the come up, about 3-5 percent of the cicadas are infected by spores, which are conidia or asexually reproducing cells, and multiply by the thousands within the bug while hoping to spread to more and more cicadas in the trees. This is known as the stage I infection. A stage II infection by this parasite consists of sexually produced spores whose goal is to end up in the soil and wait, withstanding all environments, until the next cicada arises. After the infection takes place of either type of spore, the cicada essentially falls apart as their abdomen enlarges with white-spores, losing their reproductive segments as well as several of their limbs. But the catch is that, of course, the cicada doesn’t realize and therefore it carries on with its barely lifeless self and performs the tasks of any normal cicada. Including more copulation.

Pictured here is a Cicada affected with this fungus, missing half of its abdomen.

Not only do the cicadas with stage I walk around constantly with their open wound and drag along spores while the cicadas with stage II fly around spreading spores from their abdomen, but this zombie parasite also tremendously manipulates the insects sexual behaviors. As stated in the original paper in Scientific Reports, “It is relatively common to find a healthy cicada with its genitalia plunged into the abdominal spore mass of an infected partner or to see healthy cicadas attached to fragments of abdomen or terminalia that have torn free from infected partners during attempted copulation.”. But that’s not all. These parasites also cause male cicadas to take up female mating behavior and flick their wings in response to other male cicadas. One thing leads to another, and now it has been concluded that this fungus is more present in male cicadas since these infected males are now more willing to mate with both female and male cicadas, spreading the infection to both. Although many scientists and researchers (including myself) thought that maybe this parasite simply caused a feminizing effect within the insects, this practice of male wing flicking only occurs in cicadas with a stage I infection. Therefore this disproves what was previously hypothesized, since if this feminizing effect was a case, it would occur in every infection, not just the first stage.

Either way, these spores have been researched to manipulate and control a cicada’s behavior, whether it be sexual or not. But, who knows what this parasite might mean for humans as we already know how brutal and sadistic it can be. Do you think that this topic should be more heavily researched for not only cicadas wellbeing but also ours?

But next time you see a cicada, be careful it doesn’t look to you to turn you into the next real life zombie!

To read more about this new parasite affecting cicadas in the original source, click here.

Tree Lobsters Are Back!

Image result for Stick insects Tree lobsters Lord Howe

Lord Howe Tree Lobster

Tree Lobsters are actually not lobsters at all. Nor are they crustaceans.  They are actually just insects with a similarly shaped exoskeleton. But that’s not what makes them interesting. What does, is that Tree Lobsters have seemingly come back from extinction.

The Species, originally from the Lord Howe Island in the Tasman Sea between Australia and New Zealand, went extinct during the 1920’s due to becoming the main food source for an invasive rat species that came onto the island. The Tree Lobsters were only formally declared extinct in 1960 though. Since then scientist had pretty much forgotten about them.

Image result for Stick insects Tree lobsters Lord Howe

Ball’s Pyramid Stick Insect

Thus, when scientists found a small group of stick insects similar to Lord Howe Tree Lobster’s on Ball’s Pyramid, a volcanic stack 12 miles away from Lord Howe Island, in 2001, they were quite surprised. The Ball’s Pyramid stick insects were skinnier and darker but scientists were still hopeful the newly discovered insects were, in fact, the same species as the extinct Lord Howe Tree Lobsters. Scientists tested the genes of the stick bugs from Ball’s Pyramid with genes extracted from preserved Lord Howe Tree Lobsters and found out that despite some morphological variance, they are still the same species. They speculate that diet, age, and environment had caused the Ball’s Pyramid Stick Insects to look a little different. How the species got to the volcanic stack is still a mystery as the insects cannot swim but they infer that they had been carried over by birds.

The newly discovered Tree Lobsters are now being bred at the Melbourne Zoo and elsewhere in an attempt to reintroduce the species to Lord Howe Island. However, the invasive rat species on Lord Howe Island still remains a problem as it threatens the lives of over 70 different native species. In order to successfully reintroduce the Tree Lobsters back to Lord Howe, the rat problem needs to be taken care of first.

We Need Mosquitoes?!

Picture By maureen_sill, Flickr

Yes, in fact, we do need mosquitoes. And not only mosquitoes but all the other types of insects as well. A recent discovery by Anurag Agrawal, the leader of the study and a professor of ecology and evolutionary biology at Cornell University, revealed that insects are hugely important because of the roles they play in the evolution of plants. In Agrawal’s study, in which he observed the interactions of plant-eating moths and evening primroses, the primroses treated with insecticide lost through evolution the traits that protect them from insects.

 

This points to the idea that if plants don’t need to defend themselves against insects, they stop developing the traits required to defend themselves. The real shocker in this discovery, however, was how quickly the primroses adapted to this situation, in just 3-4 generations. Agrawal “was ‘very surprised’ by how quickly this process occurred, and that such surprises, ‘tell us something about the potential speed and complexities of evolution. In addition, experiments like ours that follow evolutionary change in real-time provide definitive evidence of evolution.”
But why are insects important then? Well, it is believed that many plant traits developed solely as a means of defense against insects. Some of these traits are desirable to people, like fruit’s bitter taste. In addition, with farmers trying to breed certain crops to be resistant to pests, this study shows that some genetic trade-offs might make it impossible to get certain traits in pest resistant plants. So bear with those pesky insects, as their relationship with plants is extremely important.

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