Device detects ‘olfactory fingerprints’ of harassed plants

An electronic nose that detects tomato plants infested with whiteflies could help greenhouse growers time their use of pest control. Credit: Heping Zhu, ARS, and Shaoqing Cui, Ohio State University.

A team of researchers from the Agricultural Research Service (ARS) and universities have developed an electronic nose to detect whitefly infestations on tomato plants.

The “E-Nose” works by detecting a specific cocktail of chemicals, called volatile organic compounds (VOCs), that tomato plants release into the air when attacked by whiteflies. In nature, these chemicals put other plants on high alert. Scientists hope the electronic nose will also alert growers so they can fine-tune their use of whitefly-killing insecticides, biological control agents like parasitic wasps or other measures.

According to Heping Zhu, an agricultural engineer with the ARS Application Technology Research Unit in Wooster, Ohio, who co-developed the electronic nose with collaborators from Ohio State and the University of Tennessee. -Knoxville, whiteflies are the major insect pests of American fresh produce. market tomatoes, which were valued at $721 million in 2020.

Left unchecked, adult whiteflies and their immature nymphs probe the undersides of tomato plant leaves for sap, causing them to turn yellow, curl, or drop. Whitefly feeding can also cause uneven fruit ripening and transmit viral diseases that further weaken plants.

Monitoring for whiteflies usually involves checking a threshold number of pests per leaf on a sample of plants or caught in sticky traps, both of which are time-consuming processes.

To that end, the researchers designed a prototype E-nose device the size of a shoebox that can work in the greenhouse. According to Zhu, the device mimics mammalian sense of smell and the brain’s ability to recognize certain smells. But instead of a nasal passage, receptor cells and an olfactory bulb, the electronic nose uses gas sensors, data acquisition modules and other components.

A key feature of the E-nose is a nerve-like circuit board that helps convert VOC samples from the air into digital signals. These signals are in turn transmitted to the “brain” of the system, namely a mathematical algorithm programmed to recognize specific types and concentrations – or “olfactory fingerprints” – of VOCs that tomato plants give off when attacked.

In greenhouse tests, the electronic nose displayed the VOC fingerprints of these plants as different lines with different colors that rose sharply and steadily to the right of an LED screen. Additionally, the system distinguished the olfactory fingerprints of tomato plants infested with whiteflies from those not infested, as well as plants whose leaves were punctured with pins for comparison.

With further testing and development, the electronic nose could give greenhouse growers another monitoring tool to use to decide where, when and how best to control whitefly infestations before they reach economically damaging levels. Besides whiteflies, the E-nose has also successfully detected aphids infesting tomatoes and insect pests of other greenhouse crops.

“The future E-nose system can be designed as a handheld device that allows growers to take samples from individual plants,” Zhu said. “It can also be designed as a computer-controlled, cloud-based networking system that consists of multiple smart sensors placed at different locations in the greenhouse, so the computer can automatically collect samples and monitor infestations 24 hours a day. 24.”

Details of the team’s findings were published in the October 2021 issue of Chemosensors and in the August 2019 issue of Sensors.

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More information:

Shaoqing Cui et al, Development of a portable electronic nose system for rapid diagnosis of whitefly infestation in greenhouse tomato plants, Chemosensors (2021). DOI: 10.3390/chemosensors9110297

Shaoqing Cui et al, Development of a rapid electronic nose system for early diagnosis of aphid-stressed tomato plants, Sensors (2019). DOI: 10.3390/s19163480

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united states department of agriculture

Device detects ‘smelly fingerprints’ of harassed plants (2022, Jan 17)
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