Researchers approach the “truth” of beetle ecology

Beetles are champions of survival in extremely dry environments. Part of this property is due to their ability to suck water from the air with their butts. A new joint study by researchers from the University of Copenhagen and the University of Edinburgh explains why. This knowledge will not only help explain how beetles thrive in environments where few other animals can survive, but will also ultimately help us better target global pests such as grain weevils and sunflower weevils. It may be used for delicate pest control.

Pests devour thousands of tons of food around the world every year. Food security in developing countries is particularly affected by animal species such as grain weevils and sunflowers that are specialized for surviving for thousands of years in extremely arid environments, including grain belts.

In a new study, researchers from the University of Copenhagen’s Department of Biology investigated the molecular and physiological processes underlying a beetle’s ability to survive its entire life without drinking any liquid water. One of the secrets to this characteristic lies in the rear end.

In fact, the beetle can open its rectum to take in water from humid air, convert it into liquid, and absorb it into the body. This new approach to consuming water has been known in scientific circles around the world for more than a century, but has never been fully understood until now.

“We have shed new light on the molecular mechanisms that allow beetles to absorb water from the rectum. Insects are particularly sensitive to changes in water balance, so this knowledge could help us The research could be used to develop more targeted methods to combat beetle species that destroy animals, which can be produced without killing other animals or harming humans or nature. said Kenneth Verand-Halberg, associate professor in the Department of Biology, who led the project.

Bone-dry stools demonstrate effective fluid extraction

Researchers studied the internal organs of the red potato beetle to learn more about its ability to absorb water through the rectum. The red leaf beetle is used as a so-called model organism. This provides an easy-to-handle tool and means that its ecology is similar to that found in other beetles.

Now, researchers have identified a gene that is expressed 60 times more in the rhinoceros beetle’s rectum than in the rest of the animal. This is more highly expressed than any other gene they discovered. This led them to a unique group of cells known as leptoflamata cells. A closer look revealed that these cells play an important role in the beetle’s absorption of water through its butt.

“Leptophragmata cells are small cells that sit like a window between the beetle’s kidneys and the insect’s circulatory system, or blood. Because the beetle’s kidneys surround the hindgut, the leptophragmata cells are located in the kidneys. “It works by pumping salt into their bodies, allowing them to collect water from damp areas.” “Air enters their bodies from here through their rectum. The genes we discovered direct this process. It is essential and it is new knowledge for us,” explains Kenneth Verand-Halberg.

In addition to their ability to suck water out of the air, beetles are also very effective at extracting liquids from food. Even dry grains can contain 1 to 2 percent water, which can contribute to the beetle’s fluid balance.

“Beetles can go their entire lives without drinking liquid water. This is thanks to the beetle’s modified rectum and closely placed kidneys, which together allow it to absorb the food it eats and In fact, it happens so effectively that the stool samples we tested were completely dry and free of water. There was no trace of it,” explains Kenneth Weland Halberg.

25% of world food production will be lost

Over the past 500 million years, beetles have successfully propagated on Earth. Currently, one out of every five species of animals on Earth is a beetle. Unfortunately, beetles are another pest that has a devastating impact on our food security. Red potato beetles, grain weevils, confused potato beetles, Colorado potato beetles and other types of beetles invade up to 25 percent of the world’s food supply each year.

We use about $100 billion in pesticides worldwide each year to keep insects out of our food. However, traditional pesticides harm other organisms and destroy the environment.

Therefore, according to Kenneth Veland Halberg, it is important to develop more specific and “greener” insecticides that target only pests, leaving behind more beneficial insects such as bees. A new and deeper understanding of beetle anatomy and physiology may be key here.

“We now know exactly which genes, cells and molecules are at work when the beetle absorbs water in its rectum. This could mean, for example, developing insecticides to target “By doing this, we suddenly understand how to disrupt these highly efficient processes,” says Kenneth Veland Halberg, “and in doing so kill the beetles.” I added.

“There is 20 times more insect biomass than humans on Earth. They play an important role in most food webs and have a major impact on virtually all ecosystems and human health. , we need to understand them more deeply,” the researchers conclude. .

Caption: Microscopic cross-section of the hindgut of a beetle. This photo shows dry, magenta stool surrounded by a gray rectum. The malpighian tubes of the beetle appear purple.Photo: Kenneth Verand Halberg

fact:

• Approximately one in five species on Earth are beetles. Approximately 400,000 species have been described, but the total is believed to be well over 1 million.
• Researchers discovered the red brown beetle (Tribolium castaneum) is used as a model species for research because it has a well-sequenced genome that allows the use of a wide range of genetic biology and molecular biology tools.
• Grain weevils, scarab beetles, Colorado potato beetles, and other types of beetles invade up to 25 percent of the world’s food supply each year.
• This problem is particularly acute in developing countries where access to effective pest control is limited or non-existent.
• The project was carried out in collaboration with researchers from the University of Copenhagen in Denmark, the University of Glasgow in the UK and the University of Edinburgh (Scotland).
• This study has just been published in a scientific journal. PNAS.

Caption: Grain weevils are one of the most common grain pests.Photo: Getty