| 1. |
- Kirkeby, Carsten, et al.
(author)
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Advances in automatic identification of flying insects using optical sensors and machine learning
- 2021
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Journal article (peer-reviewed)abstract
- Worldwide, farmers use insecticides to prevent crop damage caused by insect pests, while they also rely on insect pollinators to enhance crop yield and other insect as natural enemies of pests. In order to target pesticides to pests only, farmers must know exactly where and when pests and beneficial insects are present in the field. A promising solution to this problem could be optical sensors combined with machine learning. We obtained around 10,000 records of flying insects found in oilseed rape (Brassica napus) crops, using an optical remote sensor and evaluated three different classification methods for the obtained signals, reaching over 80% accuracy. We demonstrate that it is possible to classify insects in flight, making it possible to optimize the application of insecticides in space and time. This will enable a technological leap in precision agriculture, where focus on prudent and environmentally-sensitive use of pesticides is a top priority.
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| 2. |
- Boateng, Rabbi, et al.
(author)
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Mapping of Algae on Walls with a 3D Printed Hyperspectral Fluorescence Lidar
- 2023
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In: Frontiers in Optics : Proceedings Frontiers in Optics + Laser Science 2023, FiO, LS 2023 - Proceedings Frontiers in Optics + Laser Science 2023, FiO, LS 2023. - 9781957171296
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Conference paper (peer-reviewed)abstract
- Mapping of algae on facades and difficult-to-reach parts of tall buildings is demonstrated using a low-cost 3D-printed hyperspectral fluorescence lidar (HSFL). The 3D-printed HSFL has the potential for rapid and cost-effective remote assessment of algae.
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| 3. |
- Brydegaard, Mikkel, et al.
(author)
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High Dynamic Range in Entomological Scheimpflug Lidars
- 2021
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In: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X. ; 27:4
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Journal article (peer-reviewed)abstract
- 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.
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| 4. |
- Brydegaard, Mikkel, et al.
(author)
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Lidar reveals activity anomaly of malaria vectors during pan-African eclipse
- 2020
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In: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 6:20
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Journal article (peer-reviewed)abstract
- Yearly, a quarter billion people are infected and a half a million killed by the mosquito-borne disease malaria. Lack of real-time observational tools for continuously assessing the unperturbed mosquito flight activity in situ limits progress toward improved vector control. We deployed a high-resolution entomological lidar to monitor a half-kilometer static transect adjacent to a Tanzanian village. We evaluated one-third million insect observations during five nights, four days, and one annular solar eclipse. We demonstrate in situ lidar classification of several insect families and their sexes based on their modulation signatures. We were able to compare the fine-scale spatiotemporal activity patterns of malaria vectors during ordinary days and an eclipse to disentangle phototactic activity patterns from the circadian mechanism. We observed an increased insect activity during the eclipse attributable to mosquitoes. These unprecedented findings demonstrate how lidar-based monitoring of distinct mosquito activities could advance our understanding of vector ecology.
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| 5. |
- Chen, Hui, et al.
(author)
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Lidar as a Potential Tool for Monitoring Migratory Insects : A Field Case Study in Sweden
- 2024
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In: iScience. - 2589-0042. ; 27:5
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Journal article (peer-reviewed)abstract
- The seasonal migrations of insects involve a substantial displacement of biomass with significant ecological and economic consequences for regions of departure and arrival. Remote sensors have played a pivotal role in revealing the magnitude and general direction of bioflows above 150 m. Nevertheless, the take-off and descent activity of insects below this height is poorly understood. Our lidar observations elucidate the low-height dusk movements and detailed information of insects in southern Sweden from May to July, during the yearly northward migration period. Importantly, by filtering out moths from other insects based on optical information and wing beat frequency, we have introduced a promising new method to monitor the flight activities of nocturnal moths near the ground, many of which participate in migration through the area. Lidar thus holds the potential to enhance the scientific understanding of insect migratory behaviour and improve pest control strategies.
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| 6. |
- Ellerstrand, Simon Jacobsen, et al.
(author)
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Weak population genetic structure in Eurasian spruce bark beetle over large regional scales in Sweden
- 2022
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In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 12:7
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Journal article (peer-reviewed)abstract
- The Eurasian spruce bark beetle, Ips typographus, is a major pest, capable of killing spruce forests during large population outbreaks. Recorded dispersal distances of individual beetles are typically within hundreds of meters or a few kilometers. However, the connectivity between populations at larger distances and longer time spans and how this is affected by the habitat is less studied, despite its importance for understanding at which distances local outbreaks may spread. Previous population genetic studies in I. typographus typically used low resolution markers. Here, we use genome-wide data to assess population structure and connectivity of I. typographus in Sweden. We used 152 individuals from 19 population samples, distributed over 830 km from Strömsund (63° 46′ 8″ N) in the north to Nyteboda (56° 8′ 50″ N) in the south, to capture processes at a large regional scale, and a transect sampling design adjacent to a recent outbreak to capture processes at a smaller scale (76 km). Using restriction site-associated DNA sequencing (RADseq) markers capturing 1409–1997 SNPs throughout the genome, we document a weak genetic structure over the large scale, potentially indicative of high connectivity with extensive gene flow. No differentiation was detected at the smaller scale. We find indications of isolation-by-distance both for relative (FST) and absolute divergence (Dxy). The two northernmost populations are most differentiated from the remaining populations, and diverge in parallel to the southern populations for a set of outlier loci. In conclusion, the population structure of I. typographus in Sweden is weak, suggesting a high capacity to disperse and establish outbreak populations in new territories.
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| 7. |
- Jansson, Samuel, et al.
(author)
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A Scheimpflug lidar used to observe insect swarming at a wind turbine
- 2020
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In: Ecological Indicators. - : Elsevier BV. - 1470-160X. ; 117
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Journal article (peer-reviewed)abstract
- 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.
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| 8. |
- Jansson, Samuel, et al.
(author)
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Real-time dispersal of malaria vectors in rural Africa monitored with lidar
- 2021
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 16:3 March
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Journal article (peer-reviewed)abstract
- Lack of tools for detailed, real-time observation of mosquito behavior with high spatio-temporal resolution limits progress towards improved malaria vector control. We deployed a high-resolution entomological lidar to monitor a half-kilometer static transect positioned over rice fields outside a Tanzanian village. A quarter of a million in situ insect observations were classified, and several insect taxa were identified based on their modulation signatures. We observed distinct range distributions of male and female mosquitoes in relation to the village periphery, and spatio-temporal behavioral features, such as swarming. Furthermore, we observed that the spatial distributions of males and females change independently of each other during the day, and were able to estimate the daily dispersal of mosquitoes towards and away from the village. The findings of this study demonstrate how lidar-based monitoring could dramatically improve our understanding of malaria vector ecology and control options.
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| 9. |
- Jansson, Samuel, et al.
(author)
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Spatial monitoring of flying insects over a Swedish lake using a continuous-wave lidar system
- 2023
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In: Royal Society Open Science. - 2054-5703. ; 10:5
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Journal article (peer-reviewed)abstract
- We have used a continuous-wave bi-static lidar system based on the Scheimpflug principle in measurements on flying insects above, and in the vicinity of, a small lake located in a forested area in Southern Sweden. The system, which operates on triangulation principles, has a high spatial resolution at close distance, followed by a subsequent decline in resolution further from the sensor, related to the compact system design with a separation of transmitter and receiver by only 0.81 m. Our study showed a strong increase in insect abundance especially at dusk, but also at dawn. Insect numbers decreased over water compared to over land, and larger insects were over-represented over water. Further, the average size of the insects increased at night compared to day time.
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| 10. |
- Kouakou, Benoit K., et al.
(author)
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Entomological Scheimpflug lidar for estimating unique insect classes in-situ field test from Ivory Coast
- 2020
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In: OSA Continuum. - 2578-7519. ; 3:9, s. 2362-2371
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Journal article (peer-reviewed)abstract
- Acquisition of entomological data with high-frequency lidar is an emerging research field in rapid development. The technique offers very high numbers of observations per time unit, suitable for statistical models. In this work, we use a near-infrared Scheimpflug lidar with a sampling frequency of 3.5 kHz to assess the activity of free flying organisms. In-situ measurements were done during the rainy season in Ivory Coast, and hierarchical cluster analysis was used to quantify the amount of unique modulation signatures. Here we propose a method to estimate the number of observed species within a certain air volume for a given time span. This paves the way for rapid in-situ biodiversity assessment in accordance with recent priorities for protection of pollinator diversity during global changes.
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