Copenhagen, Denmark
April 19, 2021
Various beetle species have gobbled through grain stores and weakened food production worldwide since ancient times. Now, researchers at the University of Copenhagen have discovered a better way of targeting and eliminating these teeny pests. Instead of using toxic pesticides that damage biodiversity, environment and human health, the researchers seek to exploit beetles’ greatest strength against them — their precisely regulated mechanism of balancing fluids.
Wheat weevils, confused flour beetles, Colorado potato beetles and other types of beetles and insects make their ways into up to 25 percent of the global food supply. Photo: Getty
Up to 25 percent of global food production is lost annually due to insects, primarily beetles. For the past 500 million years, beetles have successfully spread and adapted to life around the globe and now account for one of every five animal species on Earth. Yet as far back as ancient Egypt, these tough little bugs have invaded granaries and vexed us humans by destroying our crops.
As a result, food production and an abundant use of pesticides now go hand in hand. A large share of these pesticides damage biodiversity, the environment and human health. As various pesticides are phased out, new solutions are required to target and eradicate pests without harming humans or beneficial insects like bees.
This is precisely what researchers from the University of Copenhagen’s Department of Biology are working on. As part of a broader effort to develop more “ecological” methods of combatting harmful insects in the near future, researchers have discovered which hormones regulate urine formation in the kidneys of beetles.
“Knowing which hormones regulate urine formation opens up the development of compounds similar to beetle hormones that, for example, can cause beetles to form so much urine that they die of dehydration,” explains Associate Professor Kenneth Veland Halberg of the University of Copenhagen’s Department of Biology. He adds:
“While it may seem a slightly vicious, there’s nothing new in us trying to vanquish pests that destroy food production. We’re simply trying to do it in a smarter, more targeted manner that takes the surrounding environment into greater account than traditional pesticides.”
Ancient Egyptians weakened beetles’ water balance using stones
The new study, as well as a previous study, also conducted by Kenneth Veland Halberg, demonstrates that beetles solve the task of regulating their water and salt balance in a fundamentally different way than other insects. This difference in insect biology is an important detail when seeking to combat certain species while leaving their neighbors alone.
“Today’s insecticides go in and paralyze an insect’s nervous system. The problem with this approach is that insect nervous systems are quite similar across species. Using these insecticides leads to the killing of bees and other beneficial field insects, and harms other living organisms,” explains Kenneth Veland Halberg.
The centrality to survival of the carefully controlled water balance of beetles is no secret. In fact, ancient Egyptians already knew to mix pebbles in grain stores to fight these pests. Stones scratched away the waxy outer layer of beetles’ exoskeletons which serves to minimize fluid evaporation.
“Never mind that they chipped an occasional tooth on the pebbles, the Egyptians could see that the scratches killed some of the beetles due to the fluid loss caused by damage to the waxy layer. However, they lacked the physiological knowledge that we have now,” says Kenneth Veland Halberg.
One-hundred billion dollars of pesticides used worldwide
Pesticides have replaced pebbles. And, their global use is now valued at roughly 100 billion dollars annually. But as rules for pesticide use become stricter, farmers are left with fewer options to fight pests.
“The incentive to develop compounds which target and eradicate pests is huge. Food production is critically dependent on pesticides. In Europe alone, it is estimated that food production would decline by 50 percent without pesticide use. With just a single, more targeted product on the market, there would almost immediately be immense gains for both wildlife and humans,” states Kenneth Veland Halberg.
But the development of new compounds to combat beetles requires, among other things, that chemists design a new molecule that resembles beetle hormones. At the same time, this compound must be able to enter beetles, either through their exoskeletons or by their feeding upon it.
“Understanding urine formation in beetles is an important step in developing more targeted and environmentally-friendly pest controls for the future. We are now in the process of involving protein chemistry specialists who can help us design an artificial insect hormone. But there is still a fair bit of work ahead before any new form of pest control sees the light of day,” concludes Associate Professor Kenneth Veland Halberg.
Facts:
- The study demonstrates that beetles regulate their kidney function in a fundamentally different way than all other insects. These differences can potentially be exploited to fatally disrupt the fluid balance of beetles without impacting other insects.
- The research data reports that this unique kidney function evolved about 240 million years ago, and that the mechanism has played a significant role in the extraordinary evolutionary triumph of beetles.
- Roughly one in five known animal species on Earth is a beetle. While 400,000 species have been described, there are thought to be well over one million beetle species in all.
- Researchers used the red flour beetle (Tribolium castaneum) as a test species for the study because it has a well-sequenced genome that allows for the deployment of a wide spectrum of genetic and molecular biology tools.
- The researchers got the beetle to urinate by injecting a hormone that scientists now know regulates urine formation in beetles.
- Wheat weevils, confused flour beetles, Colorado potato beetles and other types of beetles and insects make their ways into up to 25 percent of the global food supply every year.
- The problem is especially evident in developing countries, where access to effective pest control is limited or nonexistent.
- The project was conducted in collaboration with researchers from the University of Edinburgh, Scotland and McMaster University, Canada
- The study has just been published in the scientific journal PNAS https://doi.org/10.1073/pnas.2023314118
Biller der tisser sig selv ihjel kan blive fremtidens skadedyrsbekæmpelse
Forskellige billearter har siden oldtiden ædt sig igennem kornlagre og svækket produktionen af fødevarer verden over. Men nu har forskere fra Københavns Universitet opdaget en ny og mere målrettet metode at komme skadedyr til livs. I stedet for giftige pesticider, som ødelægger biodiversitet, miljø og menneskers sundhed, vil forskerne bruge billens største styrke, en nøje reguleret væskebalance, mod den selv.
Op imod 25 procent af den globale fødevareproduktion går i dag tabt på grund af insekter, som for en stor dels vedkommende er biller. Faktisk er hver femte dyreart på planeten en bille, som de sidste 500 millioner år effektivt har spredt sig kloden over og har, siden kornkamrene i oldtidens Egypten, generet os mennesker ved at ødelægge vores afgrøder.
Derfor er fødevareproduktion tæt forbundet med et væld af insektgifte, hvoraf en stor del har skadevirkninger på biodiversitet, miljø og menneskers sundhed. Men i takt med at forskellige insektgifte på markedet udfases, er der brug for nye løsninger, som mere målrettet dræber skadedyrerene uden at skade mennesker eller godartede insekter, såsom bier.
Og det er netop hvad forskere fra Biologisk Institut ved Københavns Universitet arbejder på. Som en del af et større projekt, der handler om at udvikle mere ”økologiske’ metoder til at bekæmpe skadelige insekter i den nærmere fremtid, har forskerne i et nyt studie fundet ud af, hvilke hormoner, der styrer dannelsen af urin i billens nyrer.
”At vi nu ved, hvilke hormoner, der styrer urindannelsen, åbner op for udviklingen af stoffer, som ligner billens hormoner og som eksempelvis kan få billerne til at danne så meget urin, at de dør af væskemangel,” forklarer lektor Kenneth Veland Halberg fra Biologisk Institut ved Københavns Universitet og tilføjer:
”Det virker måske lidt ondskabsfuldt, men der er ikke noget nyt i, at vi forsøger at nedkæmpe skadedyr, som ødelægger fødevareproduktionen. Nu forsøger vi bare at gøre det på en smartere og målrettet måde, som tager mere hensyn til det omgivende miljø end de traditionelle pesticider.”
Egypterne svækkede billens væskebalance med sten
Det nye studie, samt et tidligere studie, også lavet af Kenneth Veland Halberg, har vist at biller løser opgaven med at regulere væske- og saltbalance på en fundamentalt anderledes måde end andre insekter. Og den forskel i insekternes biologi er en vigtig detalje, når man gerne vil bekæmpe nogle arter frem for dem alle.
”I dag går de eksisterende insektgifte ind og lammer nervesystemet. Problemet med det er bare, at insekternes nervesystem ligner hinanden utrolig meget på tværs af arter. Derfor slår det også bier og andre gavnlige insekter på marken ihjel og gør skade på andre levende organismer end bare insekter,” siger Kenneth Veland Halberg.
Men at netop billernes meget nøje kontrollerede væskebalance er central for deres overlevelse, er ikke nogen hemmelighed. Faktisk var man allerede klar over det i oldtidens Egypten, hvor egypterne blandede småsten i kornlagrene for at bekæmpe skadedyrene. Stenene lavede ridser i det vokslag, som ligger på billens exoskelet, som bruges til at minimere fordampning af væske.
”Pyt med, at de så knækkede et par tænder på stenene, for egypterne kunne se, at ridserne også slog nogle af billerne ihjel på grund af den væskemangel, som ridserne i vokslaget forårsagede. De havde dog ikke den fysiologiske viden, som vi har nu,” siger Kenneth Veland Halberg.
Verden bruger for 100 milliarder dollars pesticider
I dag har pesticider erstattet sten. Og værdien af det globale årlige forbrug af pesticider ligger på ca. 100 milliarder dollars. Men i takt med at reglerne på området bliver strammere, får landmanden færre muligheder for at bekæmpe skadedyrene.
”Incitamentet for at videreudvikle stoffer, som mere målrettet går ind og dræber skadedyr, er enormt. I dag er vores fødevareproduktion kritisk afhængigt af pesticider. I Europa alene anslås det, at produktionen ville falde med 50 procent uden brug af pesticider. Får man bare ét nyt og mere målrettet produkt på markedet, vil der nærmest omgående være store gevinster for både dyr og mennesker,” siger Kenneth Veland Halberg.
Men udviklingen af nye stoffer til bekæmpelse af billerne kræver bl.a. at kemikere designer et nyt molekyle, som ligner billens egne hormoner. Samtidig skal stoffet også kunne trænge ind i billen, enten gennem exoskelettet eller ved at billen spiser det.
”Forståelsen af billernes urindannelse er et vigtigt skridt på vejen for at udvikle mere målrettet og miljøvenlig skadedyrsbekæmpelse i fremtiden. Vi er i gang med at inddrage specialister i proteinkemi, som kan hjælpe os med at designe et kunstigt insekthormon, men der ligger stadig en del arbejde forude, før en ny form for skadedyrsbekæmpelse ser dagens lys,” slutter Kenneth Veland Halberg.
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