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Background The fall armyworm (FAW) Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) invaded Myanmar and China in 2018 and greatly impacted agricultural production and ecosystem balance in these areas. FAW is a migratory insect, but its seasonal migration pattern between the two countries has been largely unknown. From 2019 to 2021, we monitored the seasonal migration of FAW in the China–Myanmar border area using a searchlight trap, assessed the reproductive development status of female migrants and traced the migratory routes by trajectory simulation. Results FAW moths were trapped by the searchlight trap in Lancang County (Yunnan, China) all year, with obvious seasonal differences in the number caught. There were small‐scale persistent trapping peaks in spring and summer, and obvious peaks in autumn; only a small number of moths were trapped in winter. Examination of the ovaries of female moths collected in different seasons showed that most females had matured, indicating that the moths were migrating and did not take off from the local area. In the migration trajectory simulation, FAW mainly migrated from Myanmar to Southwest China in spring and summer and back to Myanmar in autumn. Conclusion Our findings indicate that FAW migrates between China and Myanmar according to the monsoon circulation, which will help guide cross‐border regional monitoring and management strategies against this pest. © 2022 Society of Chemical Industry.

IntroductionRodent outbreak is the main biological disaster in grassland ecosystems. Traditional rodent damage monitoring approaches mainly depend on costly field surveys, e.g., rodent trapping or hole counting. Integrating an unmanned aircraft system (UAS) image acquisition platform and deep learning (DL) provides a great opportunity to realize efficient large-scale rodent damage monitoring and early-stage diagnosis. As the major rodent species in Inner Mongolia, Brandt’s voles (BV) (Lasiopodomys brandtii) have markedly small holes, which are difficult to identify regarding various seasonal noises in this typical steppe ecosystem.MethodsIn this study, we proposed a novel UAS-DL-based framework for BV hole detection in two representative seasons. We also established the first bi-seasonal UAS image datasets for rodent hole detection. Three two-stage (Faster R-CNN, R-FCN, and Cascade R-CNN) and three one-stage (SSD, RetinaNet, and YOLOv4) object detection DL models were investigated from three perspectives: accuracy, running speed, and generalizability.ResultsExperimental results revealed that: 1) Faster R-CNN and YOLOv4 are the most accurate models; 2) SSD and YOLOv4 are the fastest; 3) Faster R-CNN and YOLOv4 have the most consistent performance across two different seasons.DiscussionThe integration of UAS and DL techniques was demonstrated to utilize automatic, accurate, and efficient BV hole detection in a typical steppe ecosystem. The proposed method has a great potential for large-scale multi-seasonal rodent damage monitoring.

Driven by the rapidly increasing demand for intelligent materials, the sensitivity of organic materials to pressure has been intensively investigated in recent years. Many examples describe material responses to both mechanical grinding and hydrostatic pressure, but only few materials have been identified with clear colour difference as well as strong penetrability, especially under high pressure, limiting development of pressure sensors. In this work, an asymmetric luminophore, MTBA was developed by end‐capping a (Z)‐3‐(benzo[c][1,2,5]‐thiadiazol‐4‐yl)‐2‐phenylacrylonitrile (TPAN) core with propeller‐like triphenylamine (TPA) and rigid 12b‐methyl‐5,12b‐dihydroindeno[1,2,3‐kl]acridine (MeIAc) units, revealing aggregation‐induced emission (AIE) behaviour. In high‐pressure and grinding experiments, MTBA exhibits a dramatically large colour difference of up to 164 nm and 112 nm in deep‐red and near‐infrared regions, respectively, for piezochromic performance that is among the best reports for pure organic materials. The experimental and theoretical analyses indicated that the excellent piezochromic performance of MTBA is due to its highly twisty and rigid conformation, which weakens intermolecular π‐π interaction and obstructs emission quenching during compression.