Team:BGU Israel/Human Practices
One of the major insights that we have gained while working on our project, after consulting with policy makers, was that our initially planned feeding stations designed for mosquitoes will not work for several reasons, among which, are the fact that other insects will be drawn to those stations.
Thus, potential users will refuse to use them in their backyard, drawing additional mosquitoes to themselves and, statistically, those stations will not cover the local mosquito populations efficiently. Hence, after consulting with specialists, we have come to the conclusion that the best approach will be to release bacterially infected male mosquitoes, that do not bite, but will mate with females and will horizontally transfer the toxin harboring our bacteria. This approach has transformed our project, as we now had to prove that infected males indeed horizontally transfer our engineered bacteria, which we successfully did.
Below you can read the full summary of our various meetings.
Meeting with Dr. Tsurim
When we initiated our iGem team, it began with a series of meetings that were dedicated for choosing the project for iGEM. Each one of the group members came up with its own idea that aims to answer a scientific question and to address an unmet need. We had many ideas such as gluten intolerance, Psoriasis treatment or Bio materials. But eventually, we've chose to address an unmet need that can truly make an impact and save people's lives- mosquito pest control that will be both effective and ecologically beneficial.
We first approached Dr. Ido Tsurim, an ecologist, entomologist and an evolutionary biologist. He told us about Prof. Yoel Margalith, once a professor in Ben Gurion University, that discovered an unknown bacterium in a puddle in the HaBasor stream, near Kibbutz Ze’elim, in the spring of 1976. He discovered that this bacterium, Bacillus thuringiensis subsp. israelensis (Bti), produces a crystal protein, which is toxic to all mosquito larvae, but no to other insects. This discovery was a world turning point in the prolonged war against mosquito-borne diseases.
As Dr. Tsurim was Prof. Margalith's student, he has always believed in the potential of this protein. Bti is already being used around the world in big water bodies, like the Rhine river in Germany, but the unmet challenge of using the Bti is to target specifically the location where the female mosquitoes lay the larvae-hatched eggs to have an high efficient treatment. The Bti toxin is specific to mosquito larvae, highly efficient, eco-friendly and has no known resistance even after 30 years. It is recognized and recommended by the World Health Organization (WHO).
We loved this Idea because it works for all mosquito species, it is not toxic to humans or any other organism, not even to the adult mosquitoes or their eggs, and it won’t cause damage to the environment like the current pesticides. In our first meeting with Dr. Tsurim, he told us about the huge and unappreciated damage mosquitoes create in the world; from loss of property value, damage to tourism economy, commerce and to natural treasure, to a health risk that causes the loss of work ability, disability, sicknesses and deaths.
He told us about the mosquito life cycle and the difference between species in the way they lay their eggs. The female feeds on blood to get proteins in order to produce eggs. At the time of the blood meal, the female mosquito inserts saliva to the host's tissues that contains anesthetic chemicals and chemicals that prevent coagulation. The irritation is caused by these chemicals and possible infection. This is exactly the time when pathogenic microorganism in the mosquito can be inject to the host and lead to devastate diseases.
Dr. Tsurim suggested creating a transgenic mosquito that will produce the Bti toxin. This kind of method would have required a timing switch for the production to be timed with laying eggs. Our goal was to develop a simple approach that will not modify the mosquito, but rather only stop them from reproducing in urban areas.
After rounds of brain storming, we have thought why not using the mosquito's gut microbiome and genetically engineered a bacterium that will produce Bti toxin and can live in the mosquito's gut microbiome that eventually will be transferred to the laid eggs and to target the hatched larva. Our goal at that point was to design feeding stations for mosquitoes that will contain bacteria that can produce the Bti toxin.
Meeting with Dr. Papathanos
On February 11th, 2019, we met with Dr. Philippos Papathanos of the Hebrew University of Jerusalem, Rehovot
We met Dr. Papathanos at his lab at the Faculty of agriculture, food and environment of the Hebrew University of Jerusalem. Dr. Papathanos specializes in engineering insect biology.
We shared our project and our progress with him. Dr. Papathanos referred us to a few articles that might help us get a better understanding of what is being done today.
We discussed current regulation rules about genetically modified products. To his opinion, our idea is not more extreme than the gene drive idea, from a regulation point of view. Different countries have different regulation laws and countries that suffer from mosquitos transmitted diseases will be more inclined to find a solution, because no solution was yet found.
He told us that in Europe for example, a sterile transgenic male mosquito is not considered an organism by law, and hence can be released. He also said that in some countries, there are already field research that is being done to test the efficiency of different approaches. According to Dr. Papathanos, in some countries, they may even consider releasing female mosquitoes. Thus, we have rethink of a way to spread out bacteria through male mosquitoes.
We discussed how some mosquito species tend to lay eggs in the same place, like Culex mosquito, a fact that will improve the chances of success of our approach. If infected eggs with our bacteria will be laid in the dame place as other non-infected eggs, there is a higher chance that larvae from both infected and non-infected eggs will eat our bacteria with the Bti toxin. We also discussed ways in which our project can be integrated with any other existing projects that together can bring better treatment. To our inquiry about ways to attract mosquitoes to a feeding station, he answered that there is no way known to him.
We agreed that our model will be relevant to any specie, like the Asian-tiger-mosquito, Aedes albopictus, that has been found in Israel since 2002.
Dr. Papathanos taught us how to distinguish between male and female pupae by size and showed us the differences under a microscope. He showed us his colony and the ongoing research in his lab. As we had little experience with mosquitoes, it was very encouraging to find that we are working with the same tools and techniques.
As to the ecological value of mosquitoes, we discussed how mosquitoes evolve to live among us, parasite of human. We talked about how our pest control targets the mosquitos in urban areas and not all mosquitoes. Dr. Papathanos said that we must compare to existing solutions that damage the environment.
According to his website: "Phi has a background in genetic engineering and bioinformatics. His interests include synthetic elements for controlling insects and to improve our methods, tools and ultimately understanding of insect biology".
We thank Phi for sharing his knowledge and know how, since we would not have known how to separate the genders without him
Meeting with A. Yaakov
Meeting with Arye Yaakov, deputy head of the Environmental Department in the City of Beer-Sheva, Israel.
Be'er-Sheva, the Negev's capital, is the fourth metropolis in Israel. Be'er-Sheva has about 220,000 residents and provides services to approximately 750,000 residents living in the metropolitan area. Although the desert climate in the city, there are few water resources, when the main water source is the Be’er Sheva stream.
We met with Arye Yaakov, the deputy head of the Environmental Department in the city, in his office.
We learned about the pest control strategy of the department which is based on two pest control teams in the city. One team is dedicated to treat the mosquito population at the Beer Sheva's stream, and the second team is dedicated to urban preventive pest control and public complaints.
Be'er Sheva's stream is 16 KM long and highly load with organic materials. The inhabitants that survive this organic load are mostly mosquitoes, Chironomus (non-biting midges) and some turtles, indicating a minimal biodiversity in the stream. Past efforts of pest control failed, including Gambusia fish that did not survive the heavy organic load. Furthermore, the Israeli Ministry of Environmental Protection declared the stream as lacking any biological value.
Currently, pest control in Be’er Sheva city is based on Mosquito Larvicide oil (MLO), Siperin insecticide, and a dense net that prevents the larvae from coming up for air. The net is effective in this case because of the flow, whereas the pesticides are carried with the stream.
MLO is an oil (the price of MLO went up along with oil prices) with a limited effect in murky or polluted water sources.
Along with the drainage authority, the department also regulates the stream’s pathway flow and controls the flora surrounding the stream. The municipality invests ca. 20 K$ per year on stripping the vegetation around the stream. An unexpected flash-flood (which are frequent in the region) will make this investment futile.
We also learned that one of the ways to monitor the success of pest control efforts is the amount of public complaints. This parameter is of course affected from other insects that are mistaken for mosquitoes, like Chironomus and other non-biting flying insects. In addition, amount of public complaints is influenced by the media that published articles about mosquitoes that can transmit diseases and then the number of complaints raise dramatically.
Mr. Yaakov told us that he remembers hearing about Bti at a pest control conference, but never used it himself because he heard it was expensive.
The problems with the methods in use, are legal limitations to handle the floods at the stream. The major issue in urban inhabited areas is the inability to pest control in and around private properties. For example, Yaakov’s neighbor did not dry his pool in his back-yard properly and mosquitoes have probably lay their eggs in his pool. Even if citizen reports about it, the city can't do anything to exterminate without a written permission.
We presented our project and answered Yaakov's questions. We discussed in length the plan for our final product - feeding spots that contain sucrose with our bacteria, placed in pre-determined locations (according to a model that we will build). A product that can be useful to citizens and municipalities alike in urban areas. We came back to the example of the neighbor with the pool and suggested that his frustrated next-door neighbor will buy our feeding station and place it in his back yard, so the adult mosquitoes will deliver our bacteria to their eggs and stop the cycle.
Mr. Yaakov then pointed out something we haven't considered so far. The neighbor will put our feeding station in order to get rid of the mosquitoes that laid eggs in the pool next door, but it will attract more mosquitoes (and other insects) to his own back yard, and therefore will not be interested in such product.
This discussion and meeting made us drop the idea of feeding stations and we started to think of a different solution.
The Environmental Department of the city of Beer-Sheva are aware to the fact that they have a mosquito problem, and say it's being handled to the best of their knowledge and budget. With that being said, they will be happy to know about a cheaper and more efficient treatment. They are also open to the possibility of a pilot with our Trojan Mosquito project in a well-defined radius.