Beet leafhopper facts for kids

The beet leafhopper (Circulifer tenellus) is a small insect. It belongs to the leafhopper family, called Cicadellidae. These insects are part of a larger group called Hemiptera, which includes true bugs.

What They Look Like

Beet leafhoppers are small insects, usually about 3 to 3.5 millimeters long. That's about the size of a small ant! They can be greenish-yellow, tan, or olive in color. If they grow up in colder weather, they might have darker spots on their wings, back, and head.

Their body shape is often described as "wedge-shaped." This means it's wider at the front and gets narrower towards the back. Their head is wider than their body, with clear eyes. Like all insects in their group, they have special mouthparts called stylets. These are like tiny straws they use to poke into plants and suck out juices.

What They Eat

Beet leafhoppers are "generalist feeders." This means they can eat many different kinds of plants. They don't just stick to one type!

They often move between different plants depending on the season. In winter, they might eat desert weeds. But in spring and summer, they often fly to farm fields to eat crops. Their food choices can also change based on where they live. For example, beet leafhoppers in California might prefer sugar beet plants. But those in New Mexico might prefer plants like kochia or Russian thistle.

Scientists use special tools to study how insects eat. One tool is called an electrical penetration graph (EPG). It helps researchers see what parts of a plant an insect is feeding on. It can even show how fast they eat!

Understanding how beet leafhoppers eat is very important. This is because they can spread plant diseases while they feed. The beet leafhopper is the only known insect that spreads the Beet curly top virus. This virus harms plants by spreading through their sap tubes, called phloem.

Studies show that beet leafhoppers mostly drink sap from the phloem. They also drink a little from other parts of the plant. It seems they might have to work hard to pull the sap out. Other insects can just let the plant's pressure push the sap into them.

Their Life Story

How They Grow and How Many Generations

Beet leafhoppers can have many generations in one year. In places like Idaho, they usually have three generations a year. They spend the winter on plants like mustard. Female leafhoppers start laying eggs in March. The first group of adults is ready by May. Then they might fly to beet fields to mate and lay eggs for the second group. The third group becomes adults by early fall. Then they fly back to their winter homes.

Temperature greatly affects how fast they grow. Warmer temperatures mean they grow faster. The best temperatures for them are between 65°F and 95°F (18°C and 35°C). This is why they grow slower in winter. Scientists think that warmer places in the southern United States could have up to 8 generations a year. But this also depends on when food plants, like beet fields, are available.

Their Life Cycle

The beet leafhopper's life cycle has three main stages:

• Eggs: The life cycle starts with tiny eggs.
• Nymphs: After hatching, the young insects are called nymphs. They look like small adults but don't have full wings. They grow by shedding their skin five times. Each time they shed, they get a bit bigger.
• Adults: After the fifth shed, they become full-grown adults.

Their Colors

The color of beet leafhoppers can change with the seasons. Adults that grow up in warm spring and summer weather are usually light green or yellowish. But those that grow up in winter often have darker spots on their wings and back.

These color changes are likely due to temperature. Leafhoppers that grow in colder spring weather can also be darker. Scientists believe that the temperature during their last nymph stage, when their wings develop, affects their final color. Once they become adults, their color doesn't change, no matter the temperature.

Spreading Diseases

Beet leafhoppers are known for spreading diseases to plants. They act as "vectors," meaning they carry germs from one plant to another.

Citrus Stubborn Disease

Studies from the 1970s and 1980s showed that beet leafhoppers can spread a disease called Citrus Stubborn Disease. This disease is caused by a tiny germ called Spiroplasma citri.

How the Disease Spreads

The S. citri germ gets into the leafhopper when it eats an infected plant. Most of the germs die in the leafhopper's gut, but some survive. These survivors multiply inside the insect. Eventually, they reach the leafhopper's spit glands. When the infected leafhopper then feeds on a healthy plant, the germs enter the plant's sap and infect it.

This process can also harm the leafhopper itself. Many leafhoppers can die after getting infected with S. citri. Scientists think this might be because of poisons made by the germ or by the plant fighting back.

Scientists have also studied how long it takes for the leafhopper to become able to spread the disease. If the germ is injected directly into the leafhopper, it can spread the disease in about 10 days. If the leafhopper eats the germ from a plant, it takes about 16 days. They also found that the leafhopper needs to feed on an infected plant for at least 6 hours to pick up the germ.

How Spiroplasma citri Moves Inside the Leafhopper

Researchers used powerful microscopes to see how S. citri moves inside the beet leafhopper. They found the germs in the gut and spit glands. This showed that the germs travel through the insect's body. The germs often enter the leafhopper's cells in tiny bubbles. This suggests they move directly through the cells.

Scientists also saw some damage to the leafhopper's muscle cells in the gut and spit glands. This means the S. citri germ can hurt the leafhopper. However, the damage wasn't as bad as seen in other insects. This might mean that beet leafhoppers are slowly adapting to live with the S. citri germ.

Beet Curly Top Virus

The beet leafhopper is the *only* insect that spreads the beet curly top virus (BCTV). This virus causes diseases in many important crops. These include beans, sugar beet, cantaloupe, cucumber, peppers, spinach, squash, tomato, and watermelon. There are different types of this virus, but they all spread the same way.

How the Virus Spreads

Scientists use special tests to find and measure the virus inside leafhoppers. They found the virus in the gut, body fluid, and spit glands of the leafhoppers. This means the virus travels all the way through the insect's body. This is called a "circulative transmission mechanism." The leafhopper eats the virus, it gets into its gut, travels through its body, and then goes to its spit glands. When the leafhopper bites a new plant, the virus enters the healthy plant. This is similar to how Spiroplasma citri spreads.

Studies show that leafhoppers can pick up the virus very quickly. They can get it after just one hour of feeding on an infected plant. And they can spread it to new plants very soon after that. The longer they feed on an infected plant, the more virus particles they get.

Leafhoppers can keep the virus in their bodies for up to 30 days. But the amount of virus doesn't increase during this time. This suggests that the virus cannot multiply inside the leafhopper. Also, the virus is not passed down from adult leafhoppers to their young.

Scientists also used EPGs (electrical penetration graphs) to see when the virus is spread. They found that a specific feeding pattern, which happens when the leafhopper drinks phloem sap, is linked to spreading the virus. This supports the idea that the virus spreads when the leafhopper feeds on the sap of healthy plants.

Spreading to Plants They Don't Like

Beet leafhoppers prefer to lay their eggs on beet plants, even if they prefer to eat other plants. Scientists studied which plants the leafhoppers like to settle on and lay eggs on. This is important because it affects which plants get the virus.

Tests showed that leafhoppers didn't stay long on bean and tomato plants. They preferred to settle on sugar beets, radish, potato, and carrot plants. Most leafhoppers died within a week if they were kept on bean and tomato plants. They also preferred to lay eggs on beet, potato, and radish plants. No eggs were laid on carrot, bean, or tomato plants.

Even though bean and tomato plants are not good homes for the beet leafhopper, the insects can still spread the Beet Curly Top Virus to them. This means that plants that the leafhopper doesn't even like to live on can still get infected with the virus. Scientists think this might be because the virus can be spread very quickly, even after just a few hours of the leafhopper being on the plant.

See also

In Spanish: Saltahojas de la remolacha para niños