Discrimination of wood borers infested Platycladus orientalis trunks using quartz crystal microbalance gas sensor array

Trunk borers infestation is difficult to detect because larvae always mine inside trees. However, plants volatile organic compounds (PVOCs) usually change markedly after pests damage which provide us an opportunity to identify trunk borers infestation. Herein, a four-element quartz crystal microbalance (QCM) gas sensor array based on molecularly imprinted polymers (MIPs) was reported for the discrimination of Semanotus bifasciatus (Motschulsky) and Phloeosinus aubei Perris (Coleoptera: Scolytidae) infested Platycladus orientalis (L.) Franco trunks. MIPs were prepared using the methacrylic acid (MAA) polymer matrix and four characteristic PVOCs (α-pinene, β-phellandrene, 3-carene and cis-thujopsene) as templates molecules, repectively. The amounts of MIPs dropped on the QCM chips were investigated and optimized according to the sensitivities and response times. Finally, the sensor array was applied to detect PVOCs of P. orientalis trunks with S. bifasciatus and P. aubei infestation, and the response matrix were processed with principal component analysis (PCA) and linear discrimination analysis (LDA) for visualization, and further discrimination was performed by k-nearest neighbor (KNN), probabilistic neural network (PNN) and support vector machine (SVM). SVM exhibited satisfying identification accuracy rates in both calibration set (97.62 %) and validation set (93.75 %). This study may contribute to gas sensor arrays development in areas of pest control and forest protection.