Skeeter slayer: an award-winning teen uses charts and graphs to search for a natural mosquito killer.

In Adam Tazi's home state of Florida, summer's warm weather brings more than just tourists flocking to the state's sunny beaches. May through October is also a time when mosquitoes start multiplying. That ballooning population can cover your arms in itchy bites. But for 15-year-old Adam, the bloodsuckers also delivered something positive. They inspired an idea for an award-winning science fair project.

Adam learned that mosquitoes can spread diseases such as the West Nile virus. According to the Centers for Disease Control and Prevention, the illness caused by this disease killed 88 people in the United States in 2004. "Controlling mosquitoes is critical to our health," says Adam.

That's why officials sometimes spray pesticides in areas where mosquitoes breed. These toxic chemicals kill the insects. But the solution has a downside. Studies have shown that these substances may also harm other organisms, including humans. "Pesticides can cause serious damage to our health and environment," says Adam.

Adam wondered if there were ways to stomp out mosquitoes. So he designed his eighth-grade science project to find out. With careful use of charts and graphs, Adam created a project that earned him a finalist spot in the Discovery Channel Young Scientist Challenge 2004.

BUG SPRM

Adam began by conducting research on mosquito pesticides. He learned that one commonly used pesticide is a synthetic, or artificial, chemical called permethrin (pur-MEH-thrun). Adam discovered that, in addition to killing mosquitoes, the chemical can be dangerous to other organisms. According to the Environmental Protection Agency (EPA), permethrin can kill fish, as well as insects such as bees. These fliers are important pollinators that help many flowers reproduce.

Plus, Adam learned that pesticides may be harmful to humans. The EPA reports that permethrin can affect the nervous system if it is inhaled or swallowed in high doses, causing nausea, dizziness, and even death. That's why the agency regulates pesticide use, ensuring that officials spray only safe doses of the chemicals. Still, some scientists believe that the regular spraying of pesticides may pose certain health risks.

Because of the potential danger of artificial pesticides, Adam decided to test a natural chemical to see how well it controlled mosquitoes. After more research, he homed in on a fluid extracted from unripe berries of mistletoe--a plant sometimes used for holiday decorations.

Like artificial pesticides, mistletoe can be poisonous to people and some animals, such as cats and dogs. But the extract of some varieties of mistletoe has been used as a cancer treatment in several European countries. Some birds even eat mistletoe for food.

MIX IT UP

Adam wanted to learn if mistletoe is as effective as permethrin at killing mosquitoes. He also wanted to find out how much of each was needed. "I wanted to find the least amount of chemical that is still effective as a pesticide," he explains.

Under an adult's supervision and while wearing safety goggles, a mask, and gloves, Adam created a set of six solutions for mistletoe extract and another set for permethrin. To create each solution in the set, he mixed the chemical with a different amount of water. That way, each solution contained a different concentration, or percentage of chemical in the total solution: 0.1%, 0.3%, 0.5%, 1.0%, 3.0%, and 5.0%. Adam also filled one container with only water. This was his control, or the standard to which he compared his other results.

Next, Adam placed 20 mosquito larvae (immature insect form) inside each container. He left the containers for 72 hours and then checked to see how many larvae had died.

PLANT POWER

Adam had to stay organized to keep track of his variables, or characteristics that changed or could be changed, during his experiment. That's why he created a data table (see chart, right). This chart used columns and rows to arrange all of his variables--including the type of chemical, concentration, and number of mosquito larvae that died.

To better compare the results shown in his data table, Adam produced a bar graph (see graph, below). Since the chemical concentration of each solution was the characteristic that he changed, or the independent variable, he placed, that along the graph s horizontal x-axis. Along the vertical y-axis, he plotted the number of larvae that died. This is his dependent variable, or the factor that responded to the change in his experiment.

Adam was surprised by his findings. He discovered that mistletoe extract is a more effective pesticide than permethnn. Still, Adam isn't suggesting that you sprinkle mistletoe in your backyard. "First, I would like to be certain of the safety of the mistletoe extract on wildlife," he says.

Adam hopes scientists will begin to search for safer pesticides. He says, "We have to change the way we do things, including the way we control insects."

Data Table

Number of Mosquito Larvae
Killed by Different Chemical
Concentrations

  Chemical                    Mistletoe
Concentration    Permethrin    Extract

    0.1%             0            1
    0.3%             4            8
    0.5%             8           14
    1.0%             8           14
    3.0%             7           19
    5.0%             8           20

Compare the results of the solutions
in the data table. Why is it helpful
to test different concentrations of
the two chemicals?