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Minimizing insecticide use, preventing vector diseases and facilitating biodiversity assessments are suitable applications of recent advances in photonic insect surveillance and entomological lidar. The tools also comprise a new window into fundamental aspect of the fascinating life and ecology of insects and their predators in situ. At the same time, it is evident that lidars are subject to finite detection range given by the instrument noise and saturation levels, and therefore, intervals of the biomass spectra are sectioned at different ranges. The Scheimpflug lidar allows an interesting trade-off between high sample rate and low pulse energy for retrieving wing beat harmonics and slow sample rates with high pulse energy for detecting small species far away. In this paper, we review and revise calibration, sizing and associated deficiencies, and report count rates to 104 insects/minute up to 2 km range. We investigate if and how high dynamic range can be exploited in entomological lidar and also how fast and slow sample rates could complement each other and capture a wider span of the biomass spectrum. We demonstrate that smaller insect can be detected further away by long exposures and show consistency between the captured biomass size spectra. However, we find unexpected discrepancies between short and long exposures in the range distributions. We found that vertebrates as well as specular insects can saturate signals. Error sources and limitations are elaborated on. [ABSTRACT FROM AUTHOR]

• We recorded a large number of insect signals using a novel photonic sensor, to create a library of known species. • We used the recorded insect signals to evaluate two different clustering algorithms to quantify species richness. • Richness estimates were correlated between sensors and conventional traps. To mitigate ongoing insect biodiversity declines, there is a need for efficient yet accurate monitoring methods. The use of traditional catch-based survey methods is constrained both by costs and need for expertise for manual taxonomic identification. Emerging methods, such as eDNA and robotic sorting, have the potential to reduce workload but still require resource-intensive sample collection in the field. Recently, remote sensing methods such as photonic sensors have shown promise for recording large numbers of insect observations. However, accurately determining species composition in collected data remains a challenge. In this study, we investigated the potential of photonic sensors for quantifying species richness of flying insects in the field and at five sites and compared the results with estimates based on conventional Malaise traps. Firstly, we evaluated two unsupervised clustering methods using a library of measured insect signals from 42 known species. Secondly, we correlated estimated number of clusters in data recorded at five sites with species richness assessment of catches from Malaise traps. This study is based on 84,770 library- and 238,584 field individual insect recordings. Our results demonstrate that both clustering methods perform well and reflect estimates obtained by Malaise traps, indicating the potential of automated insect biodiversity monitoring. This offers the possibility of more efficient but still accurate methods for studying insect biodiversity with broader temporal and spatial coverage. [ABSTRACT FROM AUTHOR]

In this paper, we use a novel spectral polarimetric optical tomographic imaging goniometer to investigate the scattering properties of Anopheles malaria mosquitoes to aid in their detection and identification in entomological lidar applications. Mosquitoes were mounted on a turn table, on which they were illuminated from different angles with linearly polarized near-infrared light and rotated. Thus, aspect-dependent optical cross sections were retrieved in backscatter and extinction mode. The backscattering and extinction properties of male and female mosquitoes were further condensed into a pair of parameters. We investigate the wings and bodies of mosquitoes together and independently, and conclude that the wings of mosquitoes strongly scatter copolarized light and that the degree of linear polarization of light scattered by insect bodies is independent of the aspect. In lidar measurements, light scattered by insect wings can be separated from light scattered by insect bodies due to the oscillatory wing beats. Therefore, obtaining the scattering properties of bodies and wings independently is of particular interest. Finally, we conclude that 808 nm light is well suited for detecting specular reflexes produced by Anopheles wings, which has large implications for the design of entomological lidar instruments used to study malaria mosquitoes. [ABSTRACT FROM AUTHOR]

Effective monitoring of flying insects is of major societal importance in view of the role of insects as indispensable pollinators, destructive disease vectors and economically devastating agricultural pests. The present paper reports on monitoring of flying agricultural pests using a continuous-wave lidar system in a rice-field location in Southern China. Using a Scheimpflug arrangement, range resolution over several 100 m long observational paths was achieved. The system operates with two perpendicularly polarized near-infrared lasers, which are activated intermittently, and back-scattered radiation from insects was recorded by a linear array detector placed after a linear polarizer. Our polarization sensitive system was used to monitor the flying insect diurnal activity and also the influence of changes in weather conditions, e.g., the occurrence of rain. Activity strongly peaked at dusk and rose again, although to a lower extent, just before dawn. At the onset of rainfall, a strong increase in insect counts occurred which was interpreted as the rain-induced bringing down of high-altitude migrant insects. [ABSTRACT FROM AUTHOR]

• Insects swarmed at the top of a wind farm. • The insect swarm persisted well past sunset on a warm night, despite significant predation pressure from bats. • Larger insects swarmed during two nights with lower wind speeds. • Bats engaged in both feeding and social interactions at the wind farm. Wind turbines have considerable impact on flying animals, particularly bats, which are sometimes killed in large numbers by the moving rotors. A longstanding question remains why bats are attracted to wind turbines and risk their lives among the moving rotor blades. One hypothesis is that they feed on insects swarming around the turbine towers and another is that they congregate there to court. The two are not mutually exclusive and may occur more or less simultaneously. It has been difficult to distinguish these hypothesis, because techniques that permit observations of small insects over the relevant distances (~100 m) in the dark are lacking. In this study, we monitored insects at the top of a wind turbine using a novel high-resolution Scheimpflug lidar. The instrument was employed around dusk during ten late summer nights in 2018, with the principal aim to evaluate its performance under real field conditions. Insect swarms were observed near the top of the turbine tower on every night. They appeared in short intervals and varied in density, timing, exact location and size of the swarming insects from day to day. Swarms formed in the afternoon and either dispersed around sunset before the emergence of bats, or remained until darkness, when bats arrived at the turbine. Some of the bats fed there, as indicated by ultrasonic feeding-buzzes, and also engaged in social interactions possibly including courtship, as indicated by song-flights. Daily variation in the formation, dispersal and behavior of the insect swarms appeared to be influenced by temperature and wind speed and also differed among the insect species. [ABSTRACT FROM AUTHOR]