On this nanotechnology day, AZoNano talks to Erick Javier Martinez Rodriguez of The Ohio State University about his research into new nanoparticle tools that could be used as alternatives to traditional pesticides. Martinez as this investigation progresses hopes that Imperator 1800—a modified form of carbon black—can be used to help reduce the spread of mosquito-borne diseases.
What is yellow fever and why is it so dangerous?
Yellow fever is a viral hemorrhagic disease transmitted by adult female yellow fever mosquitoes Aedes aegypti. Severe symptoms such as fever, headache, muscle aches, vomiting, and fatigue can be dangerous because they can kill infected people within just 10 days.
The virus is primarily endemic to tropical regions of Africa and Latin America, where conditions are favorable for year-round mosquito breeding and where resources and vaccines are limited in underdeveloped countries.
What measures are currently in place to control mosquitoes and why are they considered ineffective?
Current measures use EPA-registered pesticides that include organophosphates such as malathion and synthetic pyrethroids, and natural pyrethrins that are sprayed as adulticides, meaning they target the adult stage of mosquitoes.
The use of these pesticides has helped reduce potential outbreaks in many countries; however, constant exposure to these chemicals has caused mosquitoes to develop resistance, meaning that mosquito populations that display resistance genes are less affected by these treatments.
Nanoparticles have previously shown potential to control mosquito vectors. Can you provide an overview of how you and your team will eradicate this invasive species in its juvenile stage and how this will help control diseases such as yellow fever?
Our team focuses on the discovery of new tools that can be used as alternatives to traditional pesticides. We aim to target the juvenile phase, specifically 1St instar larvae because it is the stage where mosquitoes are most sensitive to control agents given their small size.
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Mosquito larvae develop underwater and cannot transmit arbovirus diseases, so if we can control them as adults, we can prevent mosquitoes from reaching adulthood, thus reducing the potential for disease spread. By adding new tools and advances in technology, we can reduce the spread of the diseases they transmit.
What is carbon black and what are its current uses? How can this be translated into commercially available nanoparticles that are highly effective against insecticide-resistant mosquitoes?
Carbon black is a fine black powder composed of elemental carbon obtained from the highly controlled partial combustion and decomposition process of petroleum residues at high temperatures. Unburned carbon residues ranging in size from 10 to 500 nanometers are collected and used for rubber reinforcements in a diverse group of materials and paints in the coating industry.
To make it into a commercial product, it must go through the standard procedure for any pesticide, which includes further evaluation of its effectiveness and effects on the environment and human health, before being approved by the Environmental Protection Agency (EPA).
How does Emperor 1800 use nanomaterials to control insect populations?
Imperial 1800 (E1800) is a modified form of carbon black. Our results showed that E1800 exists as nanoparticles and larger aggregates.
E1800 nanoparticles and aggregates accumulate in the midgut (stomach) and mouthparts of larval mosquitoes, as well as the umbels (hairy structures that cover the body) and anal papillae (structures involved in salt and water balance). This accumulation of carbon black can impair larval movement, respiration, feeding, and digestion, leading to their death.
How did you test the effectiveness of Imperator 1800 and what were your results?
We assessed the acute toxicity of E1800 by exposing 1St instar Ae aegypti larvae of both pyrethroid-susceptible and pyrethroid-resistant strains to various concentrations of freshly prepared suspensions of E1800 for 48 h to assess their mortality after treatment application.
Our results show that E1800 suspensions induced concentration-dependent lethality in both mosquito strains. In addition, we also evaluated the stability of these suspensions over time, showing that both strains were toxic to mosquito larvae 12 weeks after solution preparation.
What makes Imperial 1800 potentially more effective than insecticides?
The advantage of using E1800 is that, based on our results, we found that one of its modes of action is to form conglomerates around the larval body, thereby limiting their ability to feed and move. This physical activity regimen limits the resistance problems that often occur with overexposure to a particular pesticide.
In addition to the mode of action, our study also shows that nanoparticle solutions remain toxic up to 1St Instar larvae of both strains and how 12-week solutions of E1800 formulations still showed activity against 1St instar larvae of both strains.
To our surprise, these particles actually showed higher mortality in the pyrethroid-resistant strain than in the pyrethroid-sensitive strain, which was very encouraging.
Although nanoparticles appear to have little effect on non-target organisms, there are still many concerns about their use in terrestrial and aquatic environments. Why this?
One of the reasons for these concerns is that the precise modes of action of many nanoparticles have not yet been discovered in non-target or even target organisms. It is difficult to predict the ecological consequences of the release of nanoparticles into the environment without fully understanding the mechanism of their effect on different organisms.
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For example, as described in our previous study, carbon black nanoparticles were effective after 12 weeks of suspensions, making it a long-lasting product with lasting effects on mosquito larvae. While this is encouraging for mosquito control, it raises concerns about its effects on other aquatic and terrestrial organisms over time.
What needs to be investigated before Imperial 1800 or other CNPs can be safely used to control insect populations?
Although we found very promising data, we do not recommend using E1800 as a control for rearing mosquitoes.
Further research is needed to gather sufficient data to support the use of carbon black in water bodies without adverse effects on other organisms.
Some studies have raised concerns about the effects of carbon black on the environment and human health, although more data are needed to support this claim. With this in mind, our study at least provides information on the toxicity of carbon black in both larval strains, which is very promising.
After your initial research is successful, what are the next steps for your research? and what partners do you hope to accompany you along the way?
We would welcome a partnership with a company in the industry to help us further define the mode of action of E1800 and its effects on non-target organisms. We are also interested in testing E1800 with additional mosquito species and other forms of carbon black at other life stages (e.g., adult mosquitoes) to determine its full potential as a mosquito control agent.
About Erick Javier Martinez Rodriguez
Dr. Erick Javier Martinez Rodriguez in the Department of Entomology at Ohio State University. Peter is a graduate student in Piermarini’s lab. He earned a Bachelor of Science in Agricultural Science from the El Zamorano Pan-American School of Agriculture in his home country of Honduras. His research includes the toxicological and behavioral activities of natural extracts from plants and animals on mosquitoes and other pests.
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