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

Tick Genome Contains Good News and Bad News

An international collaboration of scientists led by Purdue University has sequenced the genome of the deer tick, Ixodes scapularis.  The deer tick is of particular interest because of its role in transmitting Lyme Disease and a number of other viruses to humans.  The sequenced genome, along with some proteins and biological pathways that were also identified, could help researchers find ways to prevent the transmission of tick-borne disease and develop new vaccines.  The genome also revealed that ticks have a large number of detoxifying enzymes that make it difficult to develop chemicals to effectively kill them.  At the same time, about 20 percent of the genome contains genes that appear to be unique to ticks, which could be targeted in new tick control methods.
The idea of better pest control is always touchy, because as we invent new ways to kill them they are developing resistance to those ways.  The already high number of detoxifying enzymes these ticks have will probably make it that much easier for them to adapt in this way.  As much as I hate ticks, I have to admit that all the adaptations found in these ticks to make them efficient parasites that often go undetected by their hosts pretty incredible, worthy of being called "highly evolved."  If you want to know what these other adaptations are, go read the article.

Nanotechnology Could Make Barbecues at the Jersey Shore More Relaxing

     A patent for technology that uses nanoparticles to interfere with the genetic code of mosquitos and possibly other pests. Researchers at Kansas State University have received a patent for "Double-Stranded RNA-Based Nanoparticles for Insect Gene Silencing." (US Patent 8,841,272).  Potentially this discovery could target a specific organism to interfere with their genetic code essentially killing the specific pest without harm to others.  Current pest control measures can possibly contain toxic chemicals that could cause harm to other living things and not just the intended target .  Dr. Kun Yah Zhu describes the process used in the article by creating a specifically designed dsRNA that would be ingested by the pest creating a chain reaction that would destroy the messanger RNA.  
The process is called RNA interference or RNAi.


    When fully developed, this research has numerous possibilities under the current design.  It would reduce the amount of harmful chemicals used around the home and in the yard.  It would create a safer and pest free environment for children and pets  Think of the applications it could have in farming and live stock.  No more harmful pesticides in the produce or livestock feed.  I personally wonder if this could delete an entire species of pest all together.  Could this be the breakthrough we have been looking for to make organic and healthy foods more affordable to everyone?  The article does not talk about estimated costs to produce the product for commercial and private use.  Anyone who has hosted or attended a barbecue in the summer at the jersey shore knows a product like this will be almost as loved as the jersey corn on their plate.


http://phys.org/news/2014-11-patent-awarded-genetics-based-nanotechnology-mosquitoes.html
http://www.nature.com/nbt/journal/v25/n11/full/nbt1107-1231.html

Genetic Modification of Fruit Flies

 



     National Geographic recently issued an article about fruit fly studies. An international team of entomologists led by Kansas State University's Yoonseong Park, recently discovered how to decrease some insects' sexual desire, by shutting off a certain chemical in the brain. The entomologists uncovered the neuropeptide, natalisin, while studying the genomes of red flour beetles and fruit flies. Neuropeptides carry information from one neuron to the next. Park and his colleagues turned off the natalisin, and the insects "turned off" as well. In the study, the researcher's used RNA interference (RNAi), to silence natalisin in the beetles' and flies' genes. The male and female red flour beetles who were suppressed of natalisin laid 50 to 75 percent fewer eggs than the average, but still copulated. For the fruit flies however, the natalisin suppressed males show significant delay in commencing any female pursuit. The natalisin suppressed females displayed extreme elevated levels of grooming, in turn preventing the males from approaching the females for attempted copulation. All together, the study revealed that only about 10 percent of the flies suppressed of natalisin acted busy as usual. 
     So why interfere? Park hopes his teams findings will lead to environmentally friendly pest control. Genetic pest control has the ability to kill or knock out genes specific to that insect. Natalisin has evolved with insects, meaning that shutting it off could present an extensive form of crop protection that does not affect plants or other animals. For the future, researchers are trying to find out how the neuropeptide works, what it does in other insects, and how to best create a realistic pest control.

I chose this article because we have been working with fruit flies in lab for weeks and it definitely fit the topic. After reading this I found out more about fruit flies than I'd known. The fact that this study is trying to create a pest control as well is an added bonus in a positive direction.



(Article) http://newswatch.nationalgeographic.com/2013/09/10/why-genetically-modified-flies-dont-want-sex/

Link: http://newswatch.nationalgeographic.com/2013/09/10/why-genetically-modified-flies-dont-want-sex/

Genetically Engineered Mosquitoes as Pest Control

A recent article published in the New York Time highlighted an interesting genetic development. Scientists at Oxitec have developed genes in mosquitoes that kill their offspring before they reach the adult stage and thus before they can bite humans. They achieved this by creating a gene that kills the mosquito unless it has a supply of tetracycline. In labs they are bred and large populations are grown. Once mature; the males are released into the wild where the antibiotic is not available. The result in theory is that the bugs will bred before they die and pass this terminal gene onto their offspring.

There are still many worries about this pest treatment. Main problems include the releasing of only males. As the mosquito species used carries dengue fever there is worried that females accidentally released into the wild will cause a rise in this disease. Another worry is that the mosquitoes will develop a resistance to the gene in the wild and reverse its effects. I feel that while still in testing, this idea has serious potential for controlling a problem that plagues many parts of the world. It also has potential to be much more environmentally sound then conventional pesticides.