Zika virus. Malaria. West Nile virus. Dengue fever. Have you ever heard of these illnesses? If so, you likely know what they all have in common. These are a few of the diseases spread by one of the greatest pests known to humankind一the mosquito.
Much of the time, mosquito bites are just itchy. Nothing ruins a backyard barbecue faster than a mass of these bloodsucking insects. However, some mosquitoes carry viruses that cause deadly ilnesses. In fact, some experts say mosquitoes are a bigger threat to human life than any other organism.
Over the centuries, mosquitoes are thought to have caused the deaths of 52 billion people. That’s half the people who have ever lived on Earth! Even today, ilnesses spread by mosquitoes kill more people each year than war does.
It should be no surprise that many people would like to get rid of mosquitoes. What if we could wipe out the entire mosquito population? No more malaria. No more Zika. No more itchy bumps after a summer day spent outdoors. Doesn’t that sound great?
Not so fast. Sure, some species of mosquitoes harm humans. But others don’t pose any threat at al! In fact, some of these mosquitoes play important parts in their ecosystems. Let’s look at a few ways.
Many of our Wonder Friends already know that bees play an important part in pollination（授粉）. It turns out, mosquitoes do, too! Most mosquitoes actually drink nectar（ 花蜜） instead of blood. When they do so, they help pollinate the plants they feed on.
It’s also important to remember that even mosquitoes are part of an ecosystem. Without them, the food chain would be disturbed.
Adult mosquitoes are a food source for bats, birds, spiders, and small mammals. Without them, these animals would need to find something else to eat. Some experts even think mosquitoes could be used to help humans.
【小题1】What do Zika virus, Malaria, West Nile virus, and Dengue fever have in common?| A．They are all pests from the wild forest. | B．They can not be cured by human beings. |
| C．They can all be spread by mosquitoes. | D．They are all caused by bacteria. |
| A．Kill something completely. | B．Bring up in large numbers. |
| C．Control something completely. | D．Rely on something completely. |
| A．Positive. | B．Negative. | C．Critical. | D．Objective. |
| A．How mosquitoes are harmful to human beings. |
| B．How mosquitoes are helpful to human beings. |
| C．How mosquitoes cause various ilness to mankind. |
| D．How mosquitoes are eaten by small mammals. |
