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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Characterization and Interventions for Foodborne Pathogens » Research » Publications at this Location » Publication #418373
Research Project: Detection, Quantification and Characterization Technologies for Foodborne Pathogens

Location: Characterization and Interventions for Foodborne Pathogens

Title: Rapid and accurate detection of huanglongbing in citrus by elasticity testing using a piezoelectric finger

Author
item RAO, PAWAN - Drexel University
item HUANG, SHU - Drexel University
item Armstrong, Cheryl
item Capobianco Jr, Joseph
item Duan, Yong Ping
item SHIH, WEI-YENG - Drexel University
item SHIH, WAN - Drexel University

Submitted to: Analytical Methods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2025
Publication Date: 2/20/2025
Citation: Rao, P., Huang, S., Armstrong, C.M., Capobianco Jr, J.A., Duan, Y., Shih, W., Shih, W. 2025. Rapid and accurate detection of huanglongbing in citrus by elasticity testing using a piezoelectric finger. Analytical Methods. https://doi.org/10.1039/d4ay01952k.
DOI: https://doi.org/10.1039/d4ay01952k

Interpretive Summary: Huanglongbing is a devastating citrus disease with no known cure. It’s spread by an insect present in most citrus-producing areas of the US. Early detection can be central for controlling the disease because it can help identify efficient strategies for deploying the limited resources critical for effective containment. The current industry standard for detection involves a molecular, lab-based testing method that identifies the DNA of the causal organism. To aide producers, we have developed a device that utilizes mechanical parameters of the leaves instead of a genetic signature for early detection of Huanglongbing. Testing in this manner allows screening to take place in the field instead of in the laboratory and allows results to be reported in real time. It can also help eliminate the need for highly trained personnel to conduct the testing, thus converting testing to a point-of-use system for farmers in their groves. Overall, this device can potentially be used to screen trees on-site to more effectively identify areas that merit further evaluation.

Technical Abstract: Rapid and sensitive detection of citrus huanglongbing (HLB) is critical for the control of this devastating disease. In this study, we have evaluated using a piezoelectric finger (PEF) with a 0.4 mm probe to measure the elastic modulus of a leaf to detect HLB in four different species of citrus including grapefruit (GFT), pumelo (PUM), lemon (LEM), and Valencia orange (VAL). Diseased citrus leaves were harvested from trees testing positive for the presence of Candidatus Liberibacter asiaticus (Las), the causal agent of HLB, and included both symptomatic leaves, which were blotchy mottle or yellowing and asymptomatic leaves, which did not display outward symptoms. Healthy leaves were harvested from trees testing negative for Las. The results indicated that the PEF elastic modulus test exhibited an overall 94% sensitivity and 90% specificity against the Las status of the trees for all four citrus types combined. Comparative quantitative real-time polymerase chain reaction (qPCR) tests on the same leaves showed an overall 89% sensitivity and 100% specificity against the Las status of the trees. While a Cohen-Kappa coefficient of 0.81 was obtained between the PEF and qPCR predictions, suggesting a "strong" agreement between the PEF and qPCR tests, a more detailed examination indicated that PEF was more sensitive overall in detecting the Las positive trees than qPCR, particularly from asymptomatic leaves for which PEF was 96% sensitive versus 78% sensitive by qPCR, indicating the potential of using PEF for early detection of HLB.