Corn planthopper facts for kids
Quick facts for kids Peregrinus maidis |
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Auchenorrhyncha
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Delphacidae
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Peregrinus
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P. maidis
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| Peregrinus maidis (Ashmead, 1890)
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The Peregrinus maidis, also known as the corn planthopper, is a small insect. It belongs to the insect group called Hemiptera. These insects are found in many warm, tropical, and subtropical parts of the world. This includes places like southern North America, South America, Africa, Australia, Southeast Asia, and China.
The corn planthopper is a big problem for maize (corn) and similar plants. It can physically harm the plants. It also spreads several specific viruses that affect corn. These include the maize stripe virus and maize mosaic virus.
Contents
What Does the Corn Planthopper Look Like?
Male and female corn planthoppers are slightly different sizes. This is called sexual dimorphism. Males are about 2 mm long. Their wingspan is around 6 mm. Females are a bit larger, about 3 mm long. Their wingspan is about 7 mm.
These insects are mostly yellow. They have dark brown to black markings. Their color can also range from greenish-yellow to brownish-yellow. Their front wings are longer than their bodies. The back legs have several spines. They also have a large, movable spur.
Where Do Corn Planthoppers Live?
Corn planthoppers live in most tropical and subtropical areas worldwide. This includes the southeastern United States, Hawaii, Central and South America, Africa, Australia, Southeast Asia, and southern China. They like places that are low in elevation and have high humidity. Their numbers go down in areas higher than 800 meters. Scientists think they cannot move to colder places. This is because they cannot survive the winter.
The corn planthopper likely came from Australia. There, it was a pest of sorghum plants. But it quickly spread as people started growing more sugarcane and maize. These plants are closely related to sorghum. The corn planthopper mostly eats only a few types of plants. This means it is an herbivore that specializes in certain plants. If they try to live on other plants, they lay fewer eggs. They also become smaller, live shorter lives, and grow slower.
How Do Corn Planthoppers Grow?
Female corn planthoppers lay 20 to 30 eggs. They place these eggs inside the middle veins of their host plant's leaves. Usually, it takes about 20 days for a young planthopper to become an adult.
However, how fast young planthoppers grow depends a lot on the temperature. They grow best between 20-27 °C. They go through five young stages called instars. If temperatures are too hot (above 30 °C) or too cold (below 10 °C), they skip the fifth stage. They go straight from the fourth stage to an adult. But their full development takes much longer, up to 74 days. If they grow at 15 °C, they develop an extra, sixth, stage. This makes their development time about 65 days.
Corn planthoppers live in warm places. They can have babies all year round. But temperature changes still affect their growth. How much food is available also affects their growth. If plants have more Nitrogen fertilizers, the planthoppers grow faster. They also lay more eggs. More young planthoppers survive, and adults grow larger.
Different Types of Adults
Like other planthoppers, adult corn planthoppers can look different. This depends on their environment. There are two main types, or morphs.
The first type is called brachypterous. These adults have short, undeveloped wings. They usually appear when host plants are healthy. They also appear when there are not too many other planthoppers around. This means they do not need to fly far to find food.
The second type is called macropterous. These adults have fully developed wings. They appear when they need to fly to new places. This happens when there are too many planthoppers. It also happens when their current host plants are not healthy. Macropters fly away to find new, young corn plants to lay eggs on. Brachypters stay on the growing plant to feed and have babies. As a plant gets older, more macropters are born. This helps the planthoppers keep spreading.
Corn Planthoppers and Humans
Why They Are Pests
Corn planthoppers are a big problem for corn farmers. They cause damage to corn plants. The insect uses its leg spur to break into the plant's vascular tissue. Then it feeds on the plant's sap. This can make the plant wilt. Its leaves might turn yellow. The stem can become weak, and the plant might even die. Young plants or plants stressed by drought are hurt more easily.
Besides physical damage, corn planthoppers can also introduce mold and infections. This happens when they pierce the plant tissues. Just the planthopper's feeding can cause 10-15% of the corn crop to be lost.
Spreading Plant Diseases
The corn planthopper spreads several viruses that only affect corn. One is the Peregrinus maidis reovirus (PgMV). This virus does not harm the plant. However, the maize mosaic rhabdovirus (MMV) and maize tenuivirus (MStV) are harmful. They can reduce corn crop yields by 9-90%. Some people believe that the spread of corn planthoppers and these two viruses to the New World contributed to the fall of the Mayan civilization.
MMV is not passed from parent planthoppers to their babies. Instead, young planthoppers get the virus when they feed on an infected plant. Any young stage can get infected. But the virus needs about 3 weeks to develop inside the insect. After this time, the insect can spread the virus. So, usually only adult planthoppers can pass the infection to healthy plants.
Macropterous adults (those with full wings) avoid plants that show signs of MMV infection. They prefer plants that look healthy. They are likely looking for signs of a good quality host plant.
How Humans Fight the Pest
Scientists are looking for ways to reduce crop loss. They want to stop the damage from corn planthoppers and the diseases they carry. Farmers should avoid using nitrogen fertilizers. These fertilizers have been shown to help the corn planthopper thrive.
Unfortunately, corn plants do not naturally resist this pest. So, scientists are looking for other solutions. Recently, scientists have created corn with a special gene. This gene helps the plant resist the virus. This modified corn showed less infection and spread of MMV. It did not affect the planthopper's health or its ability to get infected by MMV. Instead, the gene made the plant stronger against the virus. This lowered how much the disease spread.
Images for kids
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A corn planthopper on a plant.
See also
In Spanish: Peregrinus maidis para niños
