Electronic noses based on metal oxide semiconductor sensors for detecting crop diseases and insect pests

[Display omitted] •It focuses on the detection of crop diseases and insect pests by MOS E-nose.•The history, principle, application scope and components of the E-nose are presented.•The crops analyzed are divided into food crops, cash crops, fruits and forage crops.•It also summarizes the application of E-nose in other agricultural engineering. The detection of pests and diseases is very important for agricultural production. Every year, the economic loss caused by pest infestation is enormous. The traditional methods of applying pesticides and fertilizers have negatively affected the ecological environment and human health. There is an urgent need to develop more environmentally friendly pest detection technologies. Although PCR (Polymerase Chain Reaction)-based pest control technology has high accuracy, it requires sample pretreatment and requires training of operators. In the past few years, the electronic nose (E-nose) technology that imitates the animal olfactory system has developed rapidly, and has early warning functions for pests and diseases. This technology has non-damage detection, low cost, high sensitivity, real-time analysis, simple operation, and convenient portability, etc. During the occurrence of pests, crops will release Volatile Organic Compounds (VOCs) to drive away pests, or release VOCs to attract pests' natural enemies to protect themselves. At this time, E-nose has ability to detect the type and concentration of VOCs to reflect the status of crop diseases and insect pests. Metal Oxide Semiconductor (MOS) gas sensors have the advantages of cross-sensitivity, large response range and low manufacturing price, and their arrays have been used in E-nose applications extensively. This article reviews the principle, technology and application progress of MOS electronic nose technology in detecting crop diseases and insect pests, and hopes to provide valuable information for the research on crop diseases and insect pests protection.