Reversing Insecticide Resistance Using CRISPR

 

Researchers have tested using CRISPR to reduce insecticide resistance in pests. In simple form, this was done by editing the gene which controls insecticide resistance by returning it to a wild type allele, making it susceptible to insecticides. This obviously came with ethical concern so the researchers only made it a temporary solution. Hence, why they returned the gene to wildtype rather than removing the insecticide-resistant variant genes entirely by replacing them with susceptibility to pesticide genes. They term for this is a e-Drive cassette which spreads through CRISPR gene editing which binds to Cas9 DNA and cuts out voltage gated sodium ion channel (vgsc) insecticide resistant gene site. This solution is not permanent since removing insecticide resistance lowers fitness of pests.

What the e-Drive essentially does is disable the insecticide resistance gene by using CRISPR to ensure that the wild-type gene has a 100% frequency of being passed to offspring. Since the non-resistance gene is being spread rapidly, it can spread faster than the resistance gene within just a few generations, 8 to 10 to be specific. Although the cassette was also inserted with a fitness check which limits viability or fertility. So the wild type gene spreads, increasing susceptibility and reducing pests (for example on crops), then over time the added fitness check along with the natural lower fitness takes over and the non-resistant pests eventually die out. The population returns to a normal resistant one. The beauty of this e-Drive cassette is that it can be reintroduced whenever needed, for example, if the pest problems become large again, then the e-Drive can easily be added back. It is a short term, effective, easily implemented, and easily removed strategy that the researchers hope could also work on mosquitos for malaria.

This is a great development because insecticide-resistance is rapidly spreading throughout populations of pests. While we need to control pests from destroying things like crops, it is becoming increasingly difficult to use pesticides to kill them. We also do not want the e-Drive to become out of control which could seriously harm pest populations. As the researcher says, this strategy will work without creating any other perturbation to the environment. If we can successfully increase pesticide effectiveness without entirely harming a pest population, I am all for it.

Links

https://www.sciencedaily.com/releases/2024/11/241122172740.htm

https://www.epa.gov/pesticide-registration/slowing-and-combating-pest-resistance-pesticides

How Genetics Could Help Solve the World's Bee Crisis

One of the biggest ecological crises in recent years has been the steep decline in population of bees and other pollinators. However, a recent research project carried out by Queen Mary University of London suggests that the key to solving this pollinating problem is rooted in genetics. The group of scientists behind the project analyzed the biomolecular effects of certain pesticides on the DNA and gene expression of bumblebees. After exposing the bumblebees to a common pesticide containing clothianidin, they observed drastic genetic changes that varied among the different classes of bees. The worker bees saw a change in activity level for 55 different genes, while the queen bee saw a change in 17 genes. They believe that many of these genes are more active with exposure to the pesticide in an attempt to detoxify the bee of the deadly poison. While this information is helpful in regards to the study of pesticides, it is also interesting to the general biologist, as this shows that worker bees and the queen bee have genes that are wired differently and are affected differently by the same pesticide. The team from Queen Mary University implores that we reevaluate our pesticide regulations, as their study shows disastrous effects on one specific pollinator treated with one specific pesticide. This does not even account for the countless other types of legal pesticides and the other 200,000 different pollinating insects and how they may interact with each other as well.

While the decline of the bees has received a decent amount of media coverage, I still believe that people do not grasp how truly crucial these insects are to our survival. Losing bees would mean much more than just no more honey, as without bees to pollinate plants, we would eventually run out of plants/food and pretty much all life on earth would die. That is why research like the experiment performed at Queen Mary University is so important. The ability to find exactly how a pesticide can affect the bee on a biomolecular level can provide us with enough information to decide whether or not a pesticide should be legal to use. The pesticide used in the study is an entirely legal pesticide, yet it drastically changed the gene expression of the bumblebees in a wide range of genes. This change in gene expression may affect the bumblebees ability to forage for food or reproduce. So why the pesticide itself may not directly poison and kill the bees, it is still responsible for their deaths by inhibiting their ability to survive. I think that the Environmental Protection Agency must order studies on the mechanisms and side effects of all the pesticides it currently allows to determine which ones are actually safe to use. While this is unlikely to occur, it is necessary to save the bees and keep them pollinating.

Pesticide Runoff is affecting Aquatic Mammals due to Lost Genes

Today’s Marine mammals have all evolved from terrestrial mammals that trekked back into aquatic environments and created adaptations to thrive in these new environments. One of the genes they lost in adapting to aquatic life was an enzyme that would aid in defending against pesticides. With this discovery of a missing gene in marine mammals make the issues of pesticide runoff in oceans an even more important issue in our environment. The gene responsible for this defense was labeled as PON1 which was identified to defend against organophosphates, the pesticides used in agriculture. Most marine mammals have pieced together similar enzymes to replicate the results of the PON1 gene with some exceptions being walruses, fur seals, and spotted seals, all of which would be the most vulnerable to organophosphates. Now why did these marine mammals adapt to lose this gene that their terrestrial ancestors once had? The leading theory is that due to the fact that marine mammals take in large amounts of oxygen for deep dives, they evolved to remove oxygen carrying molecules. Molecules such as PON1, that otherwise would be harmful under the pressure of deep dives. (Zimmer, 2018)

These pesticide runoffs have also started to affect coastal avian species as well as the marine mammals. There have been a rise of unidentified diseases and conditions related to issues with the organisms endocrine systems. With an organisms endocrine system being exposed to its surroundings, many believe that these pesticide runoffs are to blame for the unusual mutations and reactions of these organisms. (Tanabe, 2009)

Even though there isn't evidence that directly links the runoff to these mutations and diseases in coastal organisms such as mammals and avians, the consensus of these researchers are that the pesticides have a part to play in this ecological issue. It is impossible to know exactly where runoff from agriculture will wind up but it is a guarantee that it will reach the oceans at once point. This means that we have to be conscious of the volume of pesticides we use on our plants as well as the possible reactions that organisms in the oceans and waterways will have to these chemicals. Although there aren’t direct links to the issues marine mammals are facing, i suspect that in the coming years more information will be discovered on the effects of such pesticides on marine mammals and other ocean going species.

References

Tanabe, S. (2002, 09). Contamination and toxic effects of persistent endocrine disruptors in marine mammals and birds. Marine Pollution Bulletin, 45(1-12), 69-77. doi:10.1016/s0025-326x(02)00175-3

Zimmer, C. (2018, August 09). Marine Mammals Have Lost a Gene That Now They May Desperately Need. Retrieved from https://www.nytimes.com/2018/08/09/science/marine-mammals-pesticides.html

Insects are Increasingly Evolving Resistance to Genetically Modified Crops

The insect pictured below is known as the corn earworm or the cotton bollworm. It has evolved resistance to four proteins engineered in genetically modified crops that are supposed to keep this insect among others away from the crops. According to a new study, resistance to modified crops is on a steady rise. In 2005, there were only three reports of any type of insect resistance to the modified crops. As of 2016, there were 16 reports of resistance. In those recent cases, it took only 5 years for resistance to develop in the insects. The crops are modified to express certain genes from the bacterium Bacillus thuringiensis. The genes expressed are a type of insecticide and when insects consume the plant, they are poisoned. Reviews of past literature all show that resistance is growing not only to modified crops, but to chemical agents. With more research however, new techniques will arise to control these pests. Hopefully new research will limit chemical control and emphasize ways that will benefit not only humans, but the environment.


https://www.the-scientist.com/?articles.view/articleNo/50640/title/Insects-Are-Increasingly-Evolving-Resistance-to-Genetically-Modified-Crops/

https://phys.org/news/2017-10-pest-resistance-biotech-crops-surging.html

Experimental insecticide explodes mosquitoes

In a new study, Vanderbilt pharmacologist Jerod Denton, Ph.D., Ohio State entomologist Peter Piermarini, Ph.D., and colleagues report an experimental molecule that inhibits kidney function in mosquitoes. What is interesting is that the molecule only affects the kidney function in mosquitoes, and not in other insects. The researchers used the mosquito Anopheles gambiae , which is the leading vector for both malaria and the Zika virus.

Over the past few decades, mosquitoes have evolved genetic resistances to different types of pesticides, making them harder to eliminate. Most of these pesticides target the nervous system, so Jerod Denton, Ph.D decided to try a different approach which target the kidneys. Essentially, the researchers are preventing mosquitoes from producing urine after they take a blood meal. The waste backs up and has no where to go, killing the mosquito. In order to do this, they have the inhibitor known as inhibitor VU041. VU041 to be effective when applied topically, which indicates that it potentially could be adapted as a sprayed insecticide.


The most important part of VU041 is that it is not detrimental to important species in the environment, such as honeybees.

https://www.sciencedaily.com/releases/2016/12/161206111712.htm
https://news.vanderbilt.edu/2016/12/01/investigators-explore-new-way-to-control-mosquitoes/

Replacing Pesticides With Genetics

The Diamondback Moths have been a problem for cabbage farmers in the New York for some time. The moths are normally being treated with alternating types of pesticides. The scientists are substituting sex for spray pesticide by infusing the sprays with DNA designed to kill female larvae.


I hope this study and research is successful in a controlled dynamic to study the effects the new bugs have on the environment, before they are completely introduced into massive crop land. I'm glad that there is research being done to use less chemicals.


original article

Weed Killer, Long-Cleared, Is Doubted

Recently, an agency of the World Health Organization (WHO) determined that glyphosate, an active ingredient in Roundup, a popular weed killer, might cause cancer. Thirty years ago, Environmental Protection Agency (EPA) said the same thing. However, in 1991, EPA changed their decision and said that roundup is non carcinogenic for humans. WHO recently came up with their conclusion based off of the same mouse study that caused EPA to changed theirs.  The maker of Roundup, Monsanto is angry and accusing the agency of having an ulterior motive, and that they are picking certain data in support of its claim. Monsanto's VP said that WHO's claim goes against other studies that has tested glyphosate's safety. The recent claim demonstrates the different interpretations for the same data, and how politically complicated a change in decisions can be. Glyphosate is not only used in Roundup but in other generic products as well since its introduction in 1970 because it was considered to be non harmful in comparison to other pesticides. The California Office of Environmental Health Hazard Assessment said it was still evaluating whether glyphosate and products containing it is labeled as a cancer hazard. Some groups use this controversy in its favor to enforce the labeling of genetically modified foods (GMOs). They also want the EPA to re-evaluate glyphosate and 2,4-D, another herbicide. The different in interpretation comes form what questions and answers each agency is looking for. Currently, there is only a brief paper that has published WHO's conclusion, so it is hard to say what the thought process was behind it. Monsanto said that something can be considered carcinogenic even though it has very few evidence for a positive study.

I think the findings of this study show that there are good points from both side. I believe that Monsanto is angry because this finding, if taken seriously, will impact his company. I am glad that the WHO agency brought this topic back up because pesticide is used everyday, and a product should not continued to be used if it is not safe. I think that the WHO agency has the people's best interest while the company behind Roundup does not have the people's best interest.

Link 1: Original Article

Link 2: Supplement