By Mary Hearty

In early 2020, thousands of Kenyan farmers and rural communities suffered a severe disaster following desert locust invasion which destroyed their crops.

One swarm of locusts which can comprise of up to four million insects is estimated to eat food that can be consumed by about 35,000 people in a day.

During that time, the emergency response team was working with existing technologies such as hand-led sprayers, pumps, vehicles, and also aircrafts in the fight against the desert locusts.

However, people who were working with hand-led sprayers and vehicles, could not reach inaccessible areas, yet the locusts could prefer these areas like forests, valleys or too rocky areas.

Although aircrafts could reach those particular areas, they were not available most of the time as they are expensive, require skilled personnel and risk the pesticide being blown away by the wind to untargeted areas.

These challenges led to the need to come up with other technologies that can complement the existing ones for the future mitigation of the locust threat.

“We saw this as an opportunity to test the efficiency of drones to see if it can be used to complement the existing methods of surveillance,” Violet Ochieng’, an Agricultural Entomology student at the University of Nairobi, who piloted drone technology for surveillance of desert locusts as part of her graduate studies stated.

Violet during field experiment with spray drone at KALRO-VRI in Muguga (1)

The young researcher with her team used drones fitted with cameras to identify the location of the locusts and other pests in the field. They also used them to spray the fields infested with the pest in Samburu County and the Veterinary Science Research Institute under the Kenya Agricultural and Livestock Research Organization (KALRO) at Muguga, where the study was conducted.

They found the technology very effective as it can improve timeliness in monitoring, surveillance and early warning of desert locusts

At the beginning of their study, Ochieng’ noted that they did not have a standard operating procedure; so the survey drone was launched at different heights to capture the images which were then analyzed to check for the type of vegetation, terrain, topography and also the soil type.

All these, she said, are important as they determine the type of technology to be used, adding that in inaccessible topographies or terrain, the drone will be a complementary method as opposed to where the terrain is accessible and vehicles can be used.

When using survey drone, their analysis found that the drone was able to capture more images at lower heights as it moves at a higher speed, even though it was time consuming. However, at higher heights, the drone captured less images which are not clear but moved faster.

Therefore, she suggested the height ranging between 50 to 70 metres as the images were clear and the drone moved a bit fast at a moderate speed.

Ochieng’ emphasized that failure to observe the standard operating procedures, especially when using spray drone can lead to contamination of untargeted organisms and the environment.

To come up with the parameters that will inform the policy makers, drone operators and the farmers on how to apply the pesticides using drone technology, the young researcher did an experiment using white papers and ink.

According to Ochieng’, the spray drone can carry a jerry can with 15 to 20 litres of pesticide depending on the size. It also uses a rechargeable battery which can last between 15 to 30 minutes.

Violet Ochieng’ with her team engaging the community members of Samburu County on the use of drone technology for surveillance of desert locusts


“When spraying at higher heights, the spray droplets was carried away by the wind to untargeted areas as they were lighter, meaning most of it were not being deposited on the target areas,” she said, “when the droplets are few, chances are high that the target organisms will become resistant to the pesticide used as they will not get sufficient dosage.”

Also, Ochieng’ said more droplets were observed when the drone was being flown at very low heights, noting that this is costly and poses threat to the environment. Besides, the papers with more droplets were near the flight route, and the papers with less droplets were placed further.

Apart from surveillance and spraying of desert locusts, Ochieng’ noted that the drones can also be used to spray on top of trees or crops which are infested by other pests such as fall armyworms.

When specific trees are infested, instead of spraying the whole area, which will waste time, the pesticide, and contaminating untargeted areas and organisms, drone can be directed to that particular area, she said.

The technology is set to revolutionize agriculture as it can be extended to other priority pests similar to the desert locusts.

The bigger drone, Ochieng’ said, can be used to spray livestock, especially farmers doing large scale farming but it can also be used to spray fertilizer, natural pest enemies, count wildlife or monitor their behavior.

The drone has shown potential for use in augmentative bio-control and now requires practical trials to evaluate its efficiency in the release of natural enemies.

The pioneer study was supported by the Centre for Agriculture and Bioscience International (CABI) in Africa and Astral Aerial Solutions, with financial support from UK Foreign Commonwealth and Development Office through Frontiers Technologies Hub.