Saving the Kingdom’s Crops

New date palm weevil detection method developed at KAUST could turn the tide against the pest and support agricultural growth

Saudi Arabia is one of the world’s leading producers of dates, with a 20% share of global production. In addition to being a major source of economic revenue, the fruit holds a distinct place in the Kingdom’s traditions and culture: a date palm features prominently on the country’s coat of arms. However, this iconic plant faces a growing threat from the red palm weevil, a 2- to 4-cm beetle originating from tropical areas in Asia. The pest has proved devastating to date palm crops in the Middle East, Africa and Europe. It lays eggs inside palms, and the larvae spend their entire four-month life cycle within the tree’s trunk, hollowing it out from the inside until the tree dies. In Saudi Arabia, weevil larvae cost the date palm industry an estimated $8.7 million in economic losses each year due to their management and eradication.

In an effort to alleviate the negative impacts the pest is having on Saudi Arabia’s date industry, the Ministry of Environment, Water and Agriculture (MEWA) has been working with KAUST to investigate new ways of detecting the red palm weevil threat at an early stage. In collaboration with Yousef Al-Fhaid at MEWA’s Date Palm Research Center, Boon Ooi, Professor of Electrical and Computer Engineering at KAUST, led a team that has developed a method of using fiber optics as a cost-effective and non-invasive means to detect the very early munching sounds of young larvae.

Their approach involves sending laser pulses from a sensing device into an optical fiber, which can be wrapped around the trunks of multiple trees over a vast area. Sound interacts with the light signal inside the fiber, changing its frequency. The fiber feeds the data back into the sensor that, with relative accuracy, separates weevil larvae sounds from background noises such as wind and birds, and then indicates which trees are healthy and which are infested. Lab-based tests on small trees demonstrated that the system reliably distinguished healthy trees from infested ones. The sensor can provide non-invasive, 24-hour, low-cost and simultaneous monitoring of around 1,000 palm trees with a 10-kilometer optic fiber, detecting larvae that are as young as 12 days old.

The researchers’ promising findings – which were supported by the multiyear, interdepartmental KAUST Sensors Initiative – have already been published in the prestigious scientific journal Scientific Reports, a Nature

MINISTRY OF ENVIRONMENT, WATER AND AGRICULTURE

“The Ministry of Environment, Water and Agriculture – represented by the Date Palm Research Center in Al-Ahsa – and KAUST have cooperated to develop a device that uses optical fibers for the early detection of the red palm weevil inside palm trunks. This device will allow hundreds of trees to be monitored 24/7, which will contribute to controlling this dangerous pest in the Kingdom of Saudi Arabia and the world.”

Dr. Yousef Al-Fhaid, Former Director-General of the Date Palm Research Center

publication. Professor Ooi’s team has started deploying its sensor system in large-scale, open-air farms in collaboration with MEWA. This has required modifications to their established system, including the use of advanced signal processing techniques that can discard the ambient noises found in such environments. The university has been leading regional efforts to combat the pest since 2018. Researchers have been working in an interdisciplinary capacity to share red palm weevil knowledge and discuss engineering methods that could be applied for the early detection of the pest via acoustic detection, olfactory chemical detection and multi-spectral imagery analysis.

Early detection is key because by the time weevil infestation causes visible signs of distress in the trees, it is too late. The earliest detectable signals of an infected tree come from the noise generated by the larvae when they move within the trunk during feeding. In addition, as the larvae work through the inside of the tree, they release chemical compounds that can be identified using chemical-olfactory detection. Another method involves detecting temperature changes in the date palm trees caused by the weevils. When the larvae eat the tree, the flow of water from the roots to the canopy is impaired, resulting in a higher temperature in the canopy. This can be observed through multi-spectral imagery using infrared technology. Other methods include using sniffing dogs capable of detecting insect pheromones, as well as inserting sound probes into a tree’s trunk to detect the munching sound of weevil larvae. While somewhat effective, these methods are largely unreliable and are often costly. KAUST researchers believe they have created a novel detection method that is cheaper, more reliable and easily scalable to large date palm plantations.

The KAUST team’s innovative solution is timely. With an estimated 80,000 date palm trees already infected in the Kingdom, this detection method could prove vital to saving crops from the palm weevil infestation. It will also be crucial to helping the Kingdom achieve its ambitious National Transformation Program target of $2.5 billion in date sales by 2030.

BOON S. OOI Professor of Electrical and Computer Engineering

AS AN ENGINEER, THERE IS NOTHING MORE REWARDING THAN WITNESSING AN IDEA BEING DEVELOPED INTO A TURNKEY SOLUTION THAT SOLVES A REALWORLD PROBLEM, ESPECIALLY ONE OF ECONOMIC IMPACT THAT AFFECTS A NATIONAL RESOURCE AND A SIGNATURE PART OF OUR CUISINE. I AM PROUD OF THIS COLLABORATION BETWEEN KAUST AND MEWA.