Berkeley Lab and USDA research could lead to new ways to fight beetle that devastates coffee crops worldwide
The coffee berry borer is the most devastating coffee pest in the world. The tiny beetle is found in most regions where coffee is cultivated, and a big outbreak can slash crop yield by 80 percent.
This colorful representation shows the dominant bacterial groups that live inside the guts of coffee berry borers from seven major coffee producing countries. The bar graph on the left shows the proportion of the most prevalent bacteria, Pseudomonas, in the gut microbiome of the collected beetles.
It’s also a caffeine fiend. The insect is the only coffee pest that uses the caffeine-rich bean as its sole source of food and shelter. It bores into the bean and spends most of its life tucked inside, where it’s exposed to what should be an extremely toxic amount of caffeine for its mass: the equivalent of a 150-pound person downing 500 shots of espresso. Caffeine is harmful to most insects and is believed to act as a natural pest repellant. So how does the coffee berry borer thrive in such a hostile environment?
It relies on the bacteria in its gut, according to new research by scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), the U.S. Department of Agriculture (USDA), and Mexico’s El Colegio de la Frontera Sur (ECOSUR). Their study appears July 14 in the journal Nature Communications.
The scientists discovered that coffee berry borers worldwide share 14 bacterial species in their digestive tracts that degrade and detoxify caffeine. They also found the most prevalent of these bacteria has a gene that helps break down caffeine. Their research sheds light on the ecology of the destructive bug and could lead to new ways to fight it.
“Instead of using pesticides, perhaps we could target the coffee berry borer’s gut microbiota. We could develop a way to disrupt the bacteria and make caffeine as toxic to this pest as it is to other insects,” says Javier Ceja-Navarro, a scientist in Berkeley Lab’s Earth Sciences Division and lead author of the paper.
Ceja-Navarro and Eoin Brodie of Berkeley Lab led the effort with the USDA’s Fernando Vega, an expert on the coffee berry borer and one of the study’s corresponding authors. Zhao Hao, Ulas Karaoz, Trent Northen, Stefan Jenkins, and Hsiao Chien-Lim of Berkeley Lab; Francisco Infante of ECOSUR; and Petr Kosina of Mexico’s International Maize and Wheat Improvement Center also contributed.
Scientists have extensively studied the beetle, but very little research has focused on how it subsists solely on coffee berries, and the Berkeley Lab and USDA-led team is the first to explore the role of the bacteria in its gut. The idea isn’t as far-fetched as it may seem. Microbes perform key functions in all ecosystems, from cycling nutrients in the soil to shaping the human immune system from inside our digestive tract.
The scientists analyzed coffee berry borers from seven coffee-producing regions: Mexico, Guatemala, Puerto Rico, Hawaii, India, Indonesia and Kenya. They also studied a colony reared at the USDA’s lab in Beltsville, Maryland. Ceja-Navarro removed the digestive tracts from hundreds of deceased beetles, a painstaking process requiring micro-tweezers and steady hands.
“Before this research, I worked with atomic force microscopy, where you have to keep your hands steady, so I got good at it,” says Ceja-Navarro. “But I had to cut down on coffee!”
The scientists immersed the gut bacteria in a special medium containing caffeine as the main nutrient, so only the bacteria that degrade caffeine survived. Fourteen bacterial species were isolated, most of which were found in beetles from all seven coffee-producing regions and the laboratory colony.
These bacteria appear to subsist on caffeine as their sole source of carbon and nitrogen. One of the bacteria, Pseudomonas fulva, was the most prevalent, according to their DNA-based geographic survey.
The scientists also screened the bacteria for a gene called ndmA that is known to transform caffeine. They found that only P. fulva possessed this gene. Ceja-Navarro surmises the other bacteria help break down caffeine using different genes.
To confirm the role of P. fulva in the degradation of caffeine, the researchers administered an antibiotic to a group of beetles that wiped out their gut microbiota. They then fed these beetles a standardized diet based on coffee beans and then analyzed their feces. The caffeine passed through their digestive tracts intact without a hint of degradation.
The scientists next added P. fulva to the beetles’ diet to restock their guts with the caffeine-degrading bacterium. The feces from these beetles were devoid of caffeine, indicating the detoxification process had been restored.
“After that, we knew gut bacteria were key to the beetle’s survival strategy and its ecology in general,” says Eoin Brodie, the study’s senior author. “This is a clear example of how microorganisms, with their rapid adaptive capabilities, can enable higher organisms to colonize new environments.”
The research was funded by the U.S. Department of Agriculture, the Laboratory Directed Research and Development program at Berkeley Lab, and Mexico’s National Council for Science and Technology.
Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov
Dan Krotz | newswise
New 3-D model predicts best planting practices for farmers
26.06.2017 | Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign
Fighting a destructive crop disease with mathematics
21.06.2017 | University of Cambridge
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...
21.07.2017 | Event News
19.07.2017 | Event News
12.07.2017 | Event News
21.07.2017 | Earth Sciences
21.07.2017 | Power and Electrical Engineering
21.07.2017 | Physics and Astronomy