Bombus pauloensis facts for kids
Quick facts for kids Bombus pauloensis |
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| Córdoba, Argentina, 2022 | |
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Bombus
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| Species: |
pauloensis
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| Distribution of Bombus pauloensis | |
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Bombus pauloensis is a type of bumblebee found in South America. It lives in countries like Colombia, Ecuador, Brazil, and Argentina. This bee was once known as Bombus atratus.
These bumblebees live in social groups called colonies. A colony includes one or more queens, many workers, and young bees (brood). What makes B. pauloensis special is that its colonies can switch between having many queens (polygynous) and just one queen (monogynous). This was the first time scientists saw this behavior in bumblebees. When there are many queens, they sometimes fight each other. Also, their nests can last for more than one year (perennial), which is rare for bumblebees.
B. pauloensis bees are very helpful for farming. They pollinate many different kinds of plants. They can live in various places across South America, from warm tropical areas to cold, high-up mountains. These bees can even control the temperature inside their nests. Worker bees use their muscles to keep the nest warm, even when the weather outside changes a lot.
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Meet the Bombus pauloensis Bee
B. pauloensis bees are mostly black. Their main body part (thorax) is completely black. Their rear body part (abdomen) is also black, but it has some lighter hairs near the end.
These bees have a long tongue. This helps them reach nectar deep inside flowers. Their antennae are also quite long. Worker bees have wings that are about 4 to 10 millimeters long. Queens are usually two to three times heavier than workers.
Where Do Bombus pauloensis Bees Live?
B. pauloensis nests are usually built on the ground. However, some nests have been found high up in trees. These bees live in many different places. They can be found in warm, tropical areas and also in cold, high-altitude mountains. This shows how well B. pauloensis can adapt to various weather conditions and food sources.
Scientists think that the climate affects whether a nest will have one queen or many queens. You can find B. pauloensis throughout South America. This includes countries like Colombia, Ecuador, Brazil, and Argentina.
How Bombus pauloensis Nests Are Built
B. pauloensis nests are usually round. They can be about 10 to 30 centimeters wide and 10 to 20 centimeters tall. If a nest is on the ground, the area where the young bees grow (brood comb) is often a few centimeters underground.
Nests can have different numbers of entrances. This doesn't seem to depend on how big the colony is. Most nests have several entrances, but usually only one or two are used often. Workers change these entrances to suit their needs. B. pauloensis also makes special "pollen feeding pockets." These are attached to groups of young bees to help them eat.
Life Cycle of a Bombus pauloensis Colony
A new colony starts when a single queen (called a foundress) builds an egg cell in a small underground space. This first group of eggs grows into the first worker bees. These workers then help the colony grow even more.
For the colony to reproduce, it needs to create new male bees (drones) and new queens. The exact way this happens isn't fully known. The colony cycle ends when the queen dies, or when the new queens leave the nest, or both.
A colony can become polygynous (many queens) if the old queen is replaced by more than one new queen. A colony becomes monogynous (one queen) if queens fight each other until only one is left. Research shows that B. pauloensis can start new colonies at any time of the year.
It takes about 6 days for eggs to hatch. They then spend 12-13 days as larvae. After that, they spend 8-12 days as pupae. Finally, it takes another 24-34 days to become fully grown bees. In colder, high-altitude places, egg development might be a bit slower. So, the colony cycle can change depending on where the bees live.
Bee Behavior in the Colony
When a Queen is Replaced
If a queen disappears from the colony, a "false queen" can take her place. This false queen is usually a worker bee that has mated. She can produce both male and female offspring. This helps the colony keep growing until new queens are born.
New colonies can even form from groups of workers without a queen. In these cases, a false queen steps in. She helps the colony develop until new queens are produced.
Many Queens in One Nest (Polygyny)
Having many queens in one nest is very rare for most bees. B. pauloensis was the first bumblebee known to do this. Colonies in cold, high-altitude areas usually have one queen and follow a yearly cycle. But colonies in warm, tropical areas often last for many years. They switch between having many queens and just one queen.
These changes happen two or three times a year. Each phase can last from several weeks to months. When a nest has many queens, they often show aggressive behaviors towards each other. They also form a pecking order, where some queens are more dominant.
Who's the Boss? Social Order Among Queens
The way queens behave in B. pauloensis is largely because of the polygynous cycle. Queens that are more dominant get better access to the young bees (brood). Less dominant queens are often pushed to the edge of the brood area. Sometimes, they are even forced out of the nest entirely.
While less dominant queens might act like workers, the dominant queens are more successful at having babies. They also usually live longer. Queens that are more dominant tend to be more aggressive. One idea is that less dominant queens stay in the nest because they might be able to reabsorb their eggs if they don't get a chance to lay them.
Queen-Queen Fights
Queens in polygynous colonies of B. pauloensis often fight. These fights happen because queens try to claim and protect their own areas within the brood clump. They might lunge at other queens who enter their space.
These conflicts can lead to the death or expulsion of rival queens by the most dominant queen. Once all other queens are gone, the dominant queen takes over the colony. This starts the monogynous (one queen) phase of the colony's life. How aggressive and dominant a queen is can be linked to things like her ovary size and age.
What the Queen Does
A queen starts a colony by building an egg cell in a small hole, usually underground. She covers the egg cell with a protective wax layer. This first queen (foundress) does everything herself before the first workers appear. She takes care of the young bees and collects nectar and pollen. She puts this food into special feeding pockets for the young bees.
Eventually, these first eggs grow into workers. Once workers are present, the queen rarely leaves the nest. Her main job becomes laying and incubating eggs. The time when the queen is alone is called the subsocial phase. The social phase begins when workers mature and start helping with the nest and foraging.
What the Workers Do
Foraging workers collect nectar and pollen. They put pollen into the larvae pockets and store nectar in "pots." These workers leave the nest often and spend most of their time outside.
House workers stay inside the nest. Their job is to care for the young bees. They feed and keep the young bees warm. In some nests, other B. pauloensis workers have been seen moving bits of leaves and debris around the nest. They break and scrape this litter with their jaws and handle it with their front legs. It's not clear why they do this. Sometimes, less dominant queens might even take on the role of house workers if they can't get their own territory to lay eggs.
How They Find Food (Foraging)
B. pauloensis bees collect nectar and pollen from many different plants. Nectar is usually stored as honey in small amounts inside the nest. These bees show a slight preference for certain flowers when collecting nectar. They especially like Eucalyptus species, Lagerstroemia indica, and Aptenia cordifolia. Their long tongue helps them collect nectar more easily from deeper flowers.
When collecting pollen, B. pauloensis is more picky. They visit fewer types of plants for pollen. This pickiness might mean that their pollen-collecting habits developed differently from their nectar-collecting habits.
Keeping Warm (Thermal Regulation)
In some places, like high-altitude tropical areas, temperatures can change a lot during the day. These changes affect when B. pauloensis and other bees fly to find food. In such places, only bees that can control their body temperature well can forage.
B. pauloensis workers can control their body temperature. This helps them survive in these changing climates. They also control the temperature inside their nests. Nests are usually kept a few degrees warmer than the outside. This nest warmth comes from heat produced by specific muscle movements of the house workers. These muscle movements are similar to those foragers use to stay warm outside. Being able to control both body and nest temperatures helps B. pauloensis colonies survive when outside temperatures drop quickly, sometimes even below freezing.
