Entomological Lidar: Target Characterization and Field Applications
Research output: Thesis › Doctoral Thesis (compilation)
In the laboratory reference work, the light-scattering properties of insects were investigated. Considerable effort has been put into the study of ex-vivo and in-vivo malaria mosquitoes in search of optical properties that may enable remote species classification. These species otherwise require capture and microscope analysis by an expert to distinguish. Dragonflies have the narrowest spectral bands so far observed in nature. In this PhD work, their scattering properties were investigated and give hints regarding possible uses of these narrow bands.
Methodological development has been pursued for improvement and optimization of instrumentation through simulation and laboratory reference measurements. Hyperspectral images of insects were used to motivate laser wavelength selection based on signal strength, information yield and laser availability. Raytracing was used to devise a passive lidar scheme and to optimise the geometry of Scheimpflug lidars. Data processing techniques for robust and accurate calibration of sizes, wing-beat frequencies with associated modulation spectra, flight headings and dispersal of insects in lidar data were developed.
Entomological lidar techniques were applied in a number of field settings around the world. In Sweden, insect swarms at the nacelle of a wind farm were observed post sunset in weather conditions associated with high bat mortality through collision with wind farms. In China, increased insect activity was observed at the onset of heavy rain. The main crepuscular activity peak of insects was observed in the short time window with decreased predation pressure around sunset, when neither birds nor bats were active. In Africa, an extra activity peak was observed at noon among mosquitoes and other crepuscular insects during a solar eclipse. Male mosquito mating swarms were observed with consistent timing and location each day, and a highly directional dispersal of mosquitoes into a village was observed every evening.
In this thesis work, peak numbers of more than a thousand insects per minute have been observed, resolved temporally and spatially at μs and cm scales, respectively, which is inconceivable with conventional entomological methods. Laboratory reference work and methodological development allow the quantification and classification of insect signals in-situ. Thereby, questions of significant ecological importance could be answered.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Award date||2020 Feb 14|
|Place of Publication||Lund|
|Publication status||Published - 2020 Jan 21|
Related research output
Research output: Chapter in Book/Report/Conference proceeding › Paper in conference proceeding
Research output: Contribution to journal › Article