Bactrocera tryoni facts for kids
Quick facts for kids Bactrocera tryoni |
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The Queensland fruit fly (Bactrocera tryoni) is a type of fly from the Tephritidae family. It belongs to an insect group called Diptera. This fly is originally from the warm, coastal areas of Queensland and northern New South Wales in Australia.
These flies are active during the day, but they mate at night. Female flies lay their eggs inside fruit. When the eggs hatch, the young flies (called larvae or maggots) eat the fruit. This makes the fruit rot and fall off the tree too early. Queensland fruit flies cause a lot of damage to Australian crops, costing millions of dollars each year. They are the most expensive insect pest for farming in Australia. They can destroy almost all the fruit in an area if there are many of them.
Strong chemicals were once used to stop them, but these are now not allowed. So, scientists are studying how these flies behave to find new ways to control them.
Contents
What Does the Queensland Fruit Fly Look Like?
Adult Queensland fruit flies are reddish-brown. They have bright yellow markings and are usually about 5–8 millimeters long. When they walk, they hold their wings flat and flick them in a special way. Their wings can spread from 4.8 to 6.3 millimeters wide. Sometimes, people might mistake them for wasps because they look a bit like them.
Sister Species
The Queensland fruit fly is part of a group of flies that look very similar but are actually different species. These are called sister species. The Queensland fruit fly has three sister species: B. neohumeralis, B. aquilonis, and B. melas.
Most of these flies live in the same areas, except for B. aquilonis. This species lives in a different part of northwest Australia. Scientists think B. aquilonis might just be a group of Queensland fruit flies that live in a separate area.
Also, Queensland fruit flies mate at night, while B. neohumeralis mate during the day. This is important because B. neohumeralis does not destroy crops. Even with this difference in behavior, these two species are almost identical in their genes. Scientists can only tell them apart using new technology. We don't fully understand how these sister species are related to each other over time.
Where Do They Live?
Queensland fruit flies like warm and humid places. That's why they are most common in eastern Australia. They are also found in New Caledonia, French Polynesia, the Pitcairn Islands, and the Cook Islands.
As fruit farming has grown in Australia, these flies have spread further inland. They can now be found in central Queensland and New South Wales. Sometimes, there are outbreaks in southern and western Australia. However, the coastal areas of Australia are usually separate from each other. This is because the dry, harsh weather in between these areas is not good for the flies. So, other parts of Australia usually stay free of this pest. This is true as long as infected fruit is not moved between regions.
Life Cycle of the Queensland Fruit Fly
The Queensland fruit fly goes through several stages in its life.
Egg Stage
After becoming an adult, a female fly waits about two weeks before laying eggs. She lays around seven eggs in a hole in a fruit. She can lay up to 100 eggs each day. These holes, called "fruit punctures," let the female reach the soft inside of the fruit. Females often lay eggs in holes made by other fruit flies. This means many eggs can be found in one spot. Queensland fruit fly females can also make their own holes, called "stings," to lay eggs.
Maggot (Larval) Stage
The eggs hatch into tiny white larvae, also called maggots, in 2–4 days if the weather is good. These maggots use their strong jaws to eat towards the center of the fruit. This causes the fruit to rot. The maggots can grow up to 9 millimeters long. They finish growing in 10 to 31 days. By this time, the fruit has likely fallen to the ground. Up to 40 maggots can grow from just one piece of fruit.
Pupal Stage
When the maggot is done eating, it chews its way out of the fruit. Then, it goes into the soil. Here, it changes into a pupa. The pupal stage can last from one week in warm weather to one month in cooler conditions. This ability to adapt to different temperatures helps the Queensland fruit fly survive in many environments.
Adult Stage
After the pupal stage, adult flies come out of the soil. This usually happens near the end of summer. Unlike some other fly pests, the Queensland fruit fly does not breed all the time. Instead, it spends the winter as an adult. Adult females can live for many months, and up to four or five groups of flies can be born each year. Adult flies can live for a year or even longer.
How Do They Behave?
What Fruits Do They Like?
Queensland fruit flies can infect almost all common fruit crops. This includes apples, avocados, cherries, citrus fruits, mangoes, peaches, pears, and tomatoes. Pineapples are one of the few fruits they don't infect.
They really like to lay their eggs in rotting fruit. But there is some evidence that they will also lay eggs in fruit that isn't fully ripe. They prefer fruits with a skin that is easy to poke through, or that already has a hole. Most research on what fruits they choose has focused on a few important crops.
Adult Feeding
Young flies (larvae) only eat the inside of fruit. But adult flies get most of their protein from bacteria found on plant leaves. Some scientists think the flies and bacteria have grown together over time. However, other studies show that these helpful bacteria are not always found in all Queensland fruit fly groups. Because they need this protein from bacteria, one way to control them is to give them artificial protein mixed with insect killer.
Mating Behavior
Queensland fruit flies mate at dusk, which is evening twilight. This is important for controlling them because it helps tell them apart from their sister species, B. neohumeralis. Even though they are very similar genetically, B. neohumeralis is not a harmful pest.
Male Attraction to Scents
Male Queensland fruit flies are very attracted to a special scent called a "cue-lure." This scent is made by people, but it is similar to smells found in nature. Male flies respond most strongly to this lure in the morning. This is probably when they are most active looking for food. Scientists are still trying to understand why they are so attracted to this scent. Only adult males who are ready to mate show this behavior. This suggests that finding a mate is linked to the cue-lure. For other types of fruit flies, this cue-lure might help males compete for mates or protect them from predators.
Laying Eggs
Queensland fruit flies lay their eggs in fruit. Females prefer to lay eggs in fruit that is sweet, juicy, and not too sour. If other female flies are already on a piece of fruit, it doesn't stop another female from landing on it. However, female flies are more likely to lay eggs in fruit where other females are already laying eggs. This leads to many young flies growing in one piece of fruit. This can be helpful for the young flies because they do better when there are more of them together.
Moving Around
Queensland fruit flies can travel widely. This helps them cause a lot of damage to farms. If there is plenty of fruit, the flies usually don't travel far (only a few hundred meters to a kilometer). But if there isn't much fruit, they can travel very long distances. Adult flies might also move to find places to spend the winter or to avoid dry or cold weather.
How Do We Control Them?
People have tried many ways to control the Queensland fruit fly. One way is to create Fruit Fly Exclusion Zones (FFEZ). In these zones, it is against the law to bring fruit into certain parts of Australia and Polynesia. For example, the fly has been found in Auckland, New Zealand, several times. This has led to quarantines to protect fruit farms there.
Lure and Kill Methods
Farmers are encouraged to use "lure and kill" methods to fight the Queensland fruit fly. These methods use a bait or lure to attract the flies. The lure can be a special smell, food, or even a color. The killing part often involves insect killers, liquid traps where the flies drown, or sticky traps they can't escape from.
When there are only a few flies, lure and kill methods are best for watching how many flies are around. When there are many flies, these methods can help reduce the number of flies. Two common lure and kill methods for Queensland fruit flies are the male annihilation technique (MAT) and the protein-bait spray (PBS).
Protein-Bait Spray
Both male and female Queensland fruit flies need proteins from bacteria on plant leaves to become ready to mate. The protein-bait spray uses this need. It mixes these necessary proteins with deadly insect killers. This mix attracts both male and female flies, which helps get rid of adult flies. Scientists are still studying how well this method works and exactly what protein attracts the flies.
Male Annihilation Technique
Male Queensland fruit flies that are ready to mate are very attracted to specific scents, like the cue-lure. A special cue-lure called Willson's lure is very good at attracting these males. When this lure is mixed with insect killers, it can be a good way to get rid of adult males. While this method has worked well for other fly species, not many controlled studies have been done to see how effective it is for the Queensland fruit fly.
Sterile Insect Technique (SIT)
One way to control these flies is to make them unable to have babies. This is done by treating young flies (pupae) with radiation. Studies show that even a small amount of radiation can make male sperm unable to create new flies. Also, the radiation does not stop the flies from hatching or flying. This means that males made sterile with a low dose of radiation can still compete with normal males.
Climate Change and the Queensland Fruit Fly
The Queensland fruit fly is originally from northeastern Australia. But as temperatures rise due to climate change, the flies have been able to spread to other parts of Australia and Polynesia. These flies can handle very high temperatures, but they need a certain minimum temperature to breed. So, global warming has helped them spread.
Even though they need a minimum temperature to survive, adult Queensland fruit flies have shown they can adapt very well. They can now survive in cooler temperatures and at higher altitudes. This ability to adapt, combined with global warming, means that the damage caused by these insects will likely increase as temperatures continue to rise. One study predicted that farm damage from Queensland fruit flies could increase by millions of dollars with even small temperature rises.
Climate Change Predictions
Rising carbon dioxide (CO2) levels might also change where Queensland fruit flies live. Computer programs that guess where the flies will be as temperatures rise predict that overall damage will increase. However, the flies might move to more southern areas. This is because northern and central Queensland could become too hot for them.
But these predictions might not be completely accurate. This is because the flies have shown a great ability to adapt to different conditions. Also, it's hard to predict how humidity will change in Australia as temperatures rise. The survival of the Queensland fruit fly depends a lot on humid weather.
- Courtice, A. C. (2006). Of Peaches and Maggots, The Story of Queensland Fruit Fly. Published by Hillside Books.
Images for kids
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A close-up of the Queensland Fruit Fly.
See also
In Spanish: Bactrocera tryoni para niños
