520 is indeed a big day! But it’s not what you think…

Two little bees flying among the flowers...

What day is today? Don’t just say 520, the answer is in this nursery rhyme. Yes, today is also World Bee Day.

01

Hiding your achievements and fame

When people mention bees, the first thing that comes to mind may be that they collect honey and sting people, but in fact, the more important role of bees is that they can pollinate many wild flowering plants in the world, including many economic crops that are vital to humans.

Worldwide, nearly 90% of wild flowering plant species rely to some extent on animal-mediated pollination for reproduction, and bees are considered the most important group of crop pollinators worldwide.

There are approximately 20,000 species of bees worldwide, and approximately 1,400 species in China.

The reason why bees can become important crop pollinators is that they have a high pollination efficiency. Their pollination efficiency is mainly related to the following factors:

First, the process of bees collecting honey is a mutually beneficial symbiotic relationship, in which the bees get food and the plants complete the reproductive process;

Secondly, the bee’s body is covered with branching hairs, which allow pollen grains to attach and transport efficiently, facilitating pollination and pollination;

Finally, bees tend to collect nectar and pollen from specific types of flowers because their body structure has adapted to these types of flowers, which can greatly improve collection efficiency.

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Bee pollination not only directly improves the output and quality of crops, but also maintains the balance and biodiversity of the ecosystem.

However, since bees always need flowers to collect nectar, many people may subconsciously think that the place with the greatest diversity of bee species may be in the warm and humid tropics.

But counterintuitively, after collecting distribution information data on more than 20,000 species of bees worldwide and conducting statistical analysis, some researchers were surprised to find that under certain circumstances, the number of bee populations in arid areas is higher than that in tropical areas.

02

You are a bee, it is a sand

Why are there more species of bees in desert areas?

As we all know, deserts are almost completely unsuitable places for plant growth.

Deserts cannot provide soil conditions for plant growth. Desert soil is mainly sand, which is difficult to retain water and fertilizer and is very poor. In addition, the amount of precipitation in the desert is pitifully small, and the water evaporates quickly and the relative humidity is low.

In addition, the temperature in the desert is an extreme case of continental climate. The temperature is very high during the day due to direct sunlight, and the ground temperature drops rapidly at night, even below 0°C. As a result, the temperature difference between day and night in the desert is very large, up to 50°C or more.

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Since bees need to collect nectar, the key condition for the existence of more species of bees in the desert must be that there are more species of flowers in the desert.

Flowers need the following conditions to exist: suitable growth temperature, sufficient light, sufficient water, and substrate soil for flower growth. The desert can only meet the condition of light, which seems to be very counterintuitive.

So is there a situation where the desert can simultaneously meet several conditions for flowers to grow and bloom?

Of course there is, and that is the "timely rain" in the desert.

When certain climatic conditions are met, heavy rain will fall in the desert, and the amount of rain will be sufficient.

The arrival of rain will completely change the situation in the desert. Part of the rainfall will convert into water vapor and rise into clouds, blocking the sun's direct sunlight on the surface and controlling the ground warming process.

At night, because water vapor is also a powerful greenhouse gas, it helps the desert maintain its temperature, thereby reducing the temperature difference between day and night in the desert.

The desert ground absorbs a lot of water, which increases its ability to retain water and fertilizer, creating the soil conditions for flowers to grow.

With the "timely rain", the temperature, light, water and soil conditions are all there, everything is ready, and the seeds underground in the desert begin to stir.

Plants that have adapted to the desert environment can sprout and bloom quickly in a short period of time, and they can attract animals from hundreds of kilometers away to come for food.

Bees are hardworking little animals that are extremely sensitive to their surroundings. They can quickly sense these signals and then reach the desert as quickly as possible, so different types of bees gather in the desert.

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Although there are more trees in tropical areas, the food they provide to bees is limited. In the desert, the climate and environment change frequently, and the distribution of resources varies from year to year, so there may be more new species.

With more species, bees naturally have more food choices. Therefore, under certain conditions, there are more bee species in deserts than in tropical areas.

03

Desert is OK, but living in the desert is not OK

The reason why many different species of bees like to live in the desert is ultimately because there is an environment in the desert that is suitable for the survival of bees at a certain period of time - there are many flowers.

However, with the impact of human activities, environmental degradation and climate warming have intensified, destroying the interdependent ecological relationship between bees and plants.

Studies have shown that species abundance and geographical distribution are related to climate change, and the number of bumblebee species decreases significantly with abnormal temperature changes.

Secondly, the overuse of chemical pesticides has also led to the disappearance of a large number of bees.

When bees are exposed to pesticides, the following outcomes may occur:

Pesticides directly kill bees; they affect the bees' nervous system, causing metabolic disorders, changing their behavior patterns and making it impossible for them to find the hive; they make it difficult for them to avoid natural enemies or they die from difficulty finding food.

The invasion of alien species also disrupts the original balance of the ecosystem, thus affecting the survival of native species.

For example, due to the influence of Italian honey bees, the population of Chinese honey bees has decreased by more than 80%.

Bees are indispensable to us. A large number of crops and various plants rely on bees for pollination in order to continue to reproduce.

If the number of bees continues to decline, without bee pollination, the shape of some fruits and vegetables will be easily deformed, and the pollen of many plants will not be spread, resulting in a sharp decline in the number of certain plants in the region. Nutritious crops such as fruits, nuts and many vegetables will gradually fail to grow effectively, which may eventually lead to an imbalance in human diet.

On World Bee Day, after learning about their "strange habit" of liking the desert, we must also remember that they do not like to live in the desert.

Let us act together to protect bees and maintain the balance of the ecosystem.

References:

[1]Orr, Michael C et al. “Global Patterns and Drivers of Bee Distribution.” Current biology : CB vol. 31,3 (2021): 451-458.e4. doi:10.1016/j.cub.2020.10.053

[2]Karp, Daniel S et al. “Crop pests and predators exhibit inconsistent responses to surrounding landscape composition.” Proceedings of the National Academy of Sciences of the United States of America vol. 115,33 (2018): E7863-E7870. doi:10.1073/pnas.1800042115

[3]Requier, Fabrice et al. “Bee and non-bee pollinator importance for local food security.” Trends in ecology & evolution vol. 38,2 (2023): 196-205. doi:10.1016/j.tree.2022.10.006

[4]Houghton, John Theodore et al. “Climate change 2001: the scientific basis.” Foreign Affairs 81 (2002): 208.

[5]Garibaldi, Lucas A et al. “Policies for Ecological Intensification of Crop Production.” Trends in ecology & evolution vol. 34,4 (2019): 282-286. doi:10.1016/j.tree.2019.01.003

[6]Soroye, Peter et al. “Climate change contributes to widespread declines among bumble bees across continents.” Science (New York, NY) vol. 367,6478 (2020): 685-688. doi:10.1126/science.aax8591

Produced by | Science Popularization China

Author: Wu Yu, Master of Molecular and Embryonic Developmental Biology

Producer｜China Science Expo

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