Researchers at the National Physical Laboratory (NPL) are currently exploring the use of microwaves as a potential pest control method. Unlike traditional chemical pesticides, which indiscriminately kill all insects, microwaves would be able to target specific insect pests and not affect other insects in the area. This new application of microwaves could benefit farmers in the developing world by providing a cheaper and more environmentally-friendly alternative to chemical pesticides.
This approach uses microwave frequencies that only affect the target insect pest whilst ignoring other insects. The specific insect pests are identified and affected by the microwaves based upon their size and structure, with the microwaves tailored to fit the specific insect pest. This is done on a trial and error basis on species individuals before entering the field. There is still the possibility of killing “useful” or “neutral” insects (such as pollinators), however the risk of this is reduced compared to chemical pesticides.
The researchers are not only looking to kill the insect pests immediately but are also looking to disrupt their reproduction and communication systems. By making them infertile or reducing the insect pests’ ability to effectively communicate with each other they could reduce their long-term survival prospects.
In the past insect pests have evolved resistance to certain chemical pesticides, leading to the need to generate new pesticides or use several pesticides in conjunction with one another. This should not be a problem for this microwave approach as the microwaves focus on body part size and shape. If either size or shape changed then the microwave transmitter could simply be re-tuned to address the new mutations.
The NPL, with a team from the University of Reading, used the green peach aphid which is one of the most important aphid virus vectors and has been shown to transmit well over 100 plant virus diseases. The Plantwise distribution map has over 200 records of areas that it has been found in.
Green peach aphids were grown in the lab and then subjected to a range of microwaves up to 100 gigahertz to see if they survived. The researchers varied the frequency, peak intensity and power of the microwaves. The results from these initial experiments were inconclusive, but the team hope to test this theory further.
It is envisaged that the microwaves would be deployed from the front of tractors using a microwave transmitter which would replace the chemical spray attachment. A potential hurdle is human acceptance of the technology, with farmers becoming worried about the effects of microwaves deployed in this way so close to their communities. However Dr Richard Dudley, Principal Research Scientist at the NPL, believes that it is perfectly safe and told Plantwise:
“I think this approach would be acceptable to farmers. The level of microwaves transmitted would also be at least 1000 times less than from a mobile mast and probably less than the mobile phone in your pocket.
“Acceptance and safety are important issues to overcome, but inherently the types of approach we are suggesting have no human health issues.”
Whilst results from the initial experiments were inconclusive these were only for the green peach aphid and the research has not yet touched upon the many other insect pests that severely reduce crop yields in the developing world. The use of microwaves is something that could transform modern agriculture and increase food security. This technology can also be used on human pests, such as the mosquito, to reduce their population sizes and perhaps reduce malaria. Whilst there is still much work to be done this technology has great potential.
More information: Wired.co.uk.
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27 September 2019