Team:SZU-China/Investigation
Investigation
As the usage of the applet increases, more and more people are paying attention to our project. Some of them made comments on the applet. among these comments, what people concerned most is the sanitation problem, especially cockroaches. Many people feel those lives are tough, and they harbour in nutritious and damp places, so dining places such as canteens and restaurants are vulnerable places. In the high-risk areas, everyone is deeply worried about the quality of their daily diet. At the same time, there are many people who want to get some basic knowledge about cockroaches through our applet platform, especially about how to kill and how to curb excessive reproduction. In order to solve everyone's concern and meet everyone's needs, we plan to carry out two activities.
First of all, we interviewed the manager of the catering industry. We chose to interview the school cafeteria where people who eat more frequent and the food reserves is more abundant. From the manager's interview, we know that the dining hall had done a lot for cockroach control. When we are still sleeping, they have to start sifting vegetables to prevent insects from being mixed in the meat. After the meal, they sprayed around the canteen and the dining hall to drive away the cockroaches and flies. However, they still can't eliminate cockroaches completely after doing so much. In order to make students eat healthily, they have to enlarge the investment on food sanitation especially cockroach control. This also increased the effort of pest disinfection and increased the consumption of funds.
Then, in order to meet the needs of the public about knowing knowledge about prevention and control more accurately, we went to Shenzhen Nanshan District Center for Disease Control and Prevention to interview Xu, who has many years of experience in prevention of pests。
Through an interview with Director Xu, we know that the government has always been responsible for the cleaning of the streets. In addition, they will regularly go to the community to teach people to kill the cockroaches effectively. In the interview, they also admitted that the use of chemical methods to kill is indeed a little unfriendly to the environment. But compared with other methods currently on the market, improved chemical reagents are relatively safe and the most efficient. In addition, Director Xu gave us advice on our project. We hope that we can ensure the controllability and efficiency. At the same cost and effectiveness, the CDC is more willing to use a more environmentally friendly biological method to eliminate cockroaches.
Our project is to use Metarhizium anisopidae as fungal insecticide, and mainly for family, so we want to design a product based on the characteristics of cockroaches and Metarhizium. In the first version of the box, we did the relevant experiments and found that the efficiency of this box is not good.
The cockroach can't go inside the box smoothly, we need to make further improvements. We learned that Professor Zhongkang Wang from Chongqing University has made great achievements in the research on Metarhizium. He also has a company in Chongqing, which is also a research institution for Metarhizium. So we came to Chongqing University and visited Professor Wang.
First of all, Professor Wang says that the design of our box is unreasonable. It is too difficult for cockroach to enter the box,and the box itself is not very attractive. Then he simply described the habit of cockroach. He said that they like to climb slopes, harbour in gaps and live in dark environment. Then he said that powder of Metarhizium isn't as convenient and effective as emulsifiable powder he recommended in the company. Emulsifiable powder can be well-attached to the non-woven fabric, and a small amount of oil can be added to make the emulsifiable powder adhere better to the cockroach surface and infect the cockroach.
In the afternoon, Professor Wang took us to visit his factory. He briefly introduced the fermentation process of some fungus. After listening to the introduction of our project, he thought highly of this . If we can manufacture it, he can help us in the mass production, listing, sales and other aspects of the products.
After the visit to Chongqing, we summarized Professor Wang's suggestions and after some discussion, designed the second generation of the box.
Q: Is the pest in the dining hall serious now? What is the main reason of the damage by pests?
A: It’s quite hard to prevent the pest but it’s under control now. As season changes, flies come frequently. Besides, our dining hall is close to a golf club, which kills pests like cockroachs and flies regularly.Meanwhile, cockroaches and other pests may be drived to the dining hall that make our work harder. Additionally, since suppliers can’t use a large quantity of pesticides to kill the pest, what we buy from them will contain some unknown spawns.
Q: What is the main way to prevent pest here?
A: First of all, there will be a staff reasonable for killing the pests around the canteen, dormitory as well as the trash bin every day. The committee of our school also hires someone professional to kill the pest regularly. What’s more, we will not purchase the vegetable that easily get damaged by pests, and it will be washed with salty water.
Q: How much does canteen spend in killing pests?
A: All in all, the school pays for it, and our aim is to make sure what we buy is safe and healthy for students. People work in our canteen work together to keep it clean, our buyer chooses some reliable suppliers, and the stuffs for washing vegetable pick out the pest inside carefully.
Q: Do you think it’s possible to kill the pests completely by doing what you mentioned just now?
A: Nobody can promise that the pest can be killed totally, but we are making the effort to control it.
Q: As we know, the canteen is using some chemical and physical methods, what do you think of using a biological way to kill the cockroach like fungus infection. Do you think it might work?
A: You need to know that canteen is not the laboratory, we are responsible for teachers and students’ health. Therefore, what we use in canteen should meet the specification and the law.We also need to get the permission of school if we use the way to kill the pests. If your product is efficient and it can pass all the checks, we would like to try using them.
Q: How does cockroach mainly impact on human life?
A: At present, it mainly affects the health of human body. The inflection of cockroach is mainly about mechanical transmission including the spread of the feces as well as spread because of touching the cockroach. As for the spread of the feces, it means the pathogen is eaten into the body and then discharged into the human digestive tract through the feces. And the second one means that, the substance secreted by the cockroach can cause Allergies, red spots, and mucous membranes.
Q: According to the current situation, how many diseases can cockroach cause?
A: There are many types, and there are about 40 kinds of bacteria that have been confirmed to be infected from the cockroaches. There are more than 10 kinds of viruses, a small number of parasites and fungi, and they can all be infected through sputum contact.
Q: What is the habit of cockroach?
A: It’s habit include activity patterns, growth cycles, feeding, and migration. In activity patterns, cockroach is afraid of light and usually stay in dark corners. In growth cycles, cockroaches belong to insects, which are incomplete metamorphosis, and the growth cycle includes: egg stage, larval stage, adult stage. Generally speaking, the egg period of cockroaches is about half a month, and the larval stages of cockroaches of different varieties are also different. Among the two cockroaches that have the greatest impact on us, the larvae of German cockroach lasts for a month, and American cockroach’s is about three months. The peak period of cockroach is from May to October. They prefer to live in groups, and there will be mutual gluttony.
Q: What measures does the CDC take to prevent and control the cockroaches?
A: We mainly conducts training and basic guidance in the prevention and treatment of cockroaches. We guide the streets, urban management departments and professional killing companies how to use drugs safely. In addition, there is also monitoring of radon density in the city. For the family, there will be lectures every years with the city management department will do it together. We will introduce the killing methods of the cockroaches and distribute the commonly used drugs.
Q: How does it work for the current killing?
A: Every year, there are millions of funds to prevent the pests. At present, it has reached 75% of control. Although the control of cockroach does not reached 100%, the number of cockroach can be controlled to a level that is insufficient. At present, we are mainly responsible for the extinction of the external environment, and schools, hospitals, vegetable markets, food processing plants have their own team to prevent it. According to the patriotic health regulations, they are obliged to control the density of the cockroaches, and there will be a regular check by health supervision departments.
Q: Today, the most effective way to kill cockroaches is chemical way, but what effect does it have on the environment?
A: t will definitely cause environmental impact. Some substances in the medicine may be enriched in water or soil before the medicament is completely decomposed, which will affect the environment. Chemical control is not the best method, but it is the quickest method. When the insect population density is too large, the commonly used methods such as physical methods are relatively slow. At present, there are three main types of chemical pesticides, including organophosphorus, pyrethroids and carbamoyl esters. These three types of insecticides are biodegradable and pharmacologically effective compared to earlier insecticides. There is also improvement in sustainability and environmental friendliness. After comprehensive evaluation of existing chemical pesticides and other methods of cockroach, it is considered that chemical methods are relatively effective and rather safe.
Q: At present, CDC only kill the cockroaches outside the street, will it have any effect on them in the family?
A: The cockroaches in the family only have more connection with people, but the disease they carry mostly comes from the external environment. The cockroaches in the family may interact with the external through places like sewers. Thus, the prevention of cockroaches on the streets can also prevent cockroaches from causing health effects in the home.
Q: Our project is to use genetic engineering methods to transform fungi and kill cockroaches with fungi. Could you give us some suggestions on it?
A: The method of biological control has been studied since the 1990s, and the effect is obvious in the controllable range of the laboratory, but it has not been fully promoted in the commercial point of view, and may have some resistance in the industrial chain and actual operation. If bio-reconstruction is used, it is desirable to ensure its controllability when used in large areas. Besides, before the product is put into use, it should be verified at the cell level and the organization level to ensure that the organisms other than mites are not damaged. In addition, as a biological product, it is necessary to consider the benefit problem, and under high-efficiency conditions, the cost needs to be controlled.
Q: How does your company guarantee the safety of the products after the production of the Metarhizium-related products?
A: Because the Metarhizium used in our products is wild-type Metarhizium from nature, even if it leaks during transportation, it has no effect on the environment. Our products are very friendly to the environment.
Q: We have learnt from the paper that Metarhizium will degenerate in the process of fermentation production, resulting in poor product quality. How can this problem be solved?
A: In the production process of our company, there is generally no such problem, because Metarhizium usually degenerates after more than 25 generations of reproduction. However, in the fermentation production process of our entire product, it will not experience so many generations of reproduction, so there will be no degradation.
Q: We are planning to use spores inside the oil to inflect cockroaches. Do you have any suggestions for our choice of formulation?
A: First, I think that oil spores are inconvenient to transpor, and secondly, it is also inconvenient to use. I suggest that you use a emulsifiable powder on a non-woven fabric, which is much more convenient. And the shelf life of the emulsifiable powder machine is much longer than the oil spores.
Q: During the process of infecting the experiment, we got some insects batryticatus. Could you identify if it is covered by the outside.
A: According to the spore morphology covered by the appearance of your worm, I think it may be a mixed spore of Metarhizium and Aspergillus. Based on our previous experimental experience, I suggest that you try to mix Metarhizium and Aspergillus to infect cockroaches. Aspergillus has a very strong penetrating effect on the epidermis. When mixed, Aspergillus penetrates the epidermis, and then the fungus can invade the corpus callosum.
Q: We designed a box for this project and made a sample model. Could you give some advice based on it?
A: In my opinion, your box has such problems: First of all, the design of the box is not conducive to the movement of the squats. I think we can imitate the technique of seamless docking when constructing a road, so that we can climb into it without knowing it. Secondly, I suggest that you can change the overall structure of the box and make a shaft at the center of the lid for the knob to switch on the bottom of the chassis. Because cockroach has a habit of drilling the gap, the lid can be twisted into a small gap to allow the crucible to be drilled, so that the product can be used conveniently.
Q: What do you think of the future of our products?
A: The original infectivity of the genus Metarhizium is relatively slow, and the transformation process can be shortened by your transformation of Metarhizium. The cockroach is infected with Metarhizium in the box and does not die immediately. Instead, it can bring Metarhizium back to the nest. Other cockroaches come into contact with it and are infected with Metarhizium. the cockroach activity after being infected with Metarhizium is reduced, and cockroaches die in the nest. The cockroach also has the habit of eating the companion's corpse, in the process of foraging, It can also infect Metarhizium aeruginosa into new mites. In this way, the nest can be annihilated under the premise of ensuring environmental protection and safety, which has a great impact on its population density.
Q: After we reformed Metarhizium, what kind of changes will happen in terms of production conditions?
A: It must be, after transferring the gene, it has a certain influence on the growth and sporulation of Metarhizium. And you need to test and determine new production conditions, such as changes in the composition of the medium and the temperature of the culture.