Electronic pest control is the name given to electrically-powered devices designed to repel or eliminate pests. This article takes a look at such devices.
With lifestyles moving towards comfortability-to-harmful levels and pseudo-cleanliness, agriculture and living places of humans have come under drastic attack from pesticides and weedicides to control various types of pests and weeds. Most pesticides and weedicides contain harmful chemicals, which can have a detrimental effect on the well-being of the society and nature.
People in urban as well as rural areas are making excessive use of various pesticides and weedicides in their daily lives in general, and in agricultural and food items in particular. Even small and marginal farmers, fruit and vegetable growers, and most modern house owners want to be free from weeds and pests like mosquitoes, cockroaches and rodents.
All types of agricultural products and food items enter the human body in one form or the other. Even pesticides and weedicides that are used to protect crop residues, grasses and plants enter the human body through agricultural and animal products.
Use of pesticides has resulted in devastating effects on humans, animals and biodiversity. Various species of birds, aquatic organisms and animals have already become extinct due to excessive use of pesticides. Humans are also suffering adverse effects, which are weakening their immune system and, hence, leading to various diseases.
Electronic pest control
Electronics has influenced almost all aspects of life from medical, entertainment and safety to sports, education, defence and so on. To control or avoid the adverse effects of harmful pesticides on humans, animals and biodiversity, electronic pest control is a desired technology.
An electronic pest control system does not use any chemicals, messy traps, poisons or other potentially harmful substances. In fact, electronic pest control does not kill pests, mosquitoes and rodents (as killing is not desired for sustainable biodiversity) but only repels them. Hence, an electronic pest repellent is an environment- and human-friendly pest control technology.
Moreover, latest electronic pest and mosquito machines are well-equipped with new air-purifying technology. These are usually based on the use of either electromagnetic, ionic or ultrasonic technology, or all in one. Electronic pest control devices based on these principles have many user-friendly features and capacities.
However, there is a need to make these devices versatile in terms of capacity (bringing these out of homes to fields) and cost-effectiveness. This article discusses the fundamentals of different electronic pest control technologies based on electromagnetic, ionic and ultrasonic principles, and the latest development towards the same.
Electronic pest control techniques
Electronic pest control is the name given to any of the several types of electrically-powered devices designed to repel or eliminate pests. This technique usually makes use of electromagnetic waves, ultrasonic waves and ions, either by themselves or clubbed together.
Ultrasonic repellers
Ultrasonic devices operate by emitting short-wavelength, high-frequency sound waves that are too high in pitch to be heard by the human ear (generally, frequencies greater than 20,000Hz are termed as ultrasonic waves). Animals like bats, dogs and rodents can hear well into the ultrasonic range.
There are insects like locusts/grasshoppers and moths/lacewings that can detect frequencies of 50kHz -100kHz and as high as 250kHz, respectively. Such high-frequency waves are also produced by insect-hunting bats. Some smartphone applications are attempting to use this technology to produce high-frequency sounds to repel mosquitoes and other insects.
Ionic repellers
The concept of radio waves or radio frequency (RF) to control the behaviour of living organisms has shown promise. Flow of RF energy through free water molecules in the body of pests and insects generates heat due to the agitation of water molecules through ionic conduction of heat.
As a result, more thermal energy is produced inside pests and insects. Therefore RF treatment for pests and insects control, without negatively affecting food items, may serve as a desired alternative to chemical (that is, using pesticides) treatments, not only for household pests and insects but also for post-harvest pest control of different commodities. This can reduce long-term impact on environment, human health and competitiveness of agricultural industries.
Electromagnetic repellers
Electromagnetic pest control uses wiring within walls, turning the whole home or office into a giant pest repeller by sending a shifting signal through the wires, tuned to irritate the pests’ nervous system. This technology does not affect humans, pets or electronics, or increase the wiring’s own electromagnetic energy. It simply changes the electromagnetic frequency to target small pests, which easily pick up these changes in electromagnetic frequencies.
Signal-generating electromagnetic frequencies are regularly turned on and off every few seconds, so that pests cannot build tolerance towards electromagnetics. As insects communicate through vibrations, electromagnetic pest control vibrations communicate with pests, disturbing their receptors and making them feel like they are in a hostile area, driving them out as a result. Electromagnetic pest control, hence, makes it difficult or impossible for pests to gather food, breed, build nests or communicate with each other.
Electric current
Systems used in the electrical treatment of weed control are of two main types: spark discharges and continuous contact. The former uses high-voltage, short-duration pulses (for example, 25kV – 60kV, 1µs – 3µs), whereas the latter uses an electrode connected to a high-voltage source (for example, 15kV, 54kW). As it touches plants, current flows for the duration of the contact time.
Plant tissue is damaged by current flow and shockwave of discharge in pulsed systems, and by rapid heating effect of electric currents in continuous contact devices. Commercial continuous contact equipment is available all over the world, for farm weed control, forest undergrowth clearance and railway track weed clearance.
Experimental systems have been developed for weed beet control (15kV rms, 50kW). These can treat infestation densities of up to 5000 stems per 10,000 square metres (one-hectare). Electrical weed control is versatile and rapid, and is cost-competitive with chemical applications if used on larger areas.
Recently, use of weak electric current, particularly from photovoltaic devices, has become popular in keeping unwanted animals away from their agriculture fields. This technique has its own limitations in terms of infrastructure and cost. Also, it is ineffective in killing or repelling pests or controlling selective weeds already existing inside fields.
State of technology
Presently, electronic pest control products use an advanced, state-of-the-art microprocessor (just like a computer) to send ultrasonic waves, electromagnetic pulses and valuable negative ions to areas where pests rest, nest and breed, effectively forcing them out and making them run away. This technology is not only effective at driving pests out but is absolutely safe for people and biodiversity.
Electronic pest control devices are user-friendly, and are available for homes and offices in different models and at affordable costs. Some also come with air-purification facilities. However, the need of the hour is to develop these electronic pest control technologies for their further effectiveness, cost-effectiveness and usefulness for large areas. These must have equal effect on pests and selective weed control in lawns, grasses and agriculture fields.
Bottlenecks of technology. Studies have described ultrasound pest control devices as ineffective, uneconomical and potentially harmful to users. Claims of effectiveness of electronic pest control, electric weed-control applications and ultrasonic control of pests are under debate.
Following are the points that must be taken into account while making use of electronic pest/weed control technology:
Keep trapping
Best results come from using ultrasonic pest repellents along with trapping.
Diminishing returns
Pests and weeds become accustomed to control techniques over time, so results may only be temporary.
Realistic expectations
Research on different electronic pest control devices has shown a decline, in addition to ineffective elimination of rodents, insects and pests.
Device location
Effective areas of electronic pest control devices are short and weak, and these are easily blocked by furniture and walls. It is important to extend their capacity.
Upgraded technology
Electronic pest control devices need to be equipped with powerful electronic chips and sensors, which can repel pests and rodents harder than before and work well on all types of pests.
Large coverage area
Almost all electronic pest control devices are effective only for an area up to 74.3sqm ~ 111.4sqm (800sqft ~ 1200sqft). This must be taken care of in the future.
Selective weed control
Electric weed control devices must be suitable for selective weed control/elimination, safe to humans, animals and crops/grasses, and powerful, cost-effective and safe.
Other requirements
All electronic pest control and electric weed control devices should be easy to use and cause no harm to humans, pets, crops, fruits, food and so on. These devices should act only when these are asked to.
Dr S.S. Verma is professor at Department of Physics, Sant Longowal Institute of Engineering and Technology, Sangrur, Punjab.
