Radar Measurements of Morphological Parameters and Species Identification Analysis of Migratory Insects

Cheng Hu,Rui Wang,Fan Zhang,Shaoyang Kong

doi:10.3390/rs11171977

Abstract

Migratory insect identification has been concerning entomology and pest managers for a long time. Their nocturnal behavior, as well as very small radar cross-section (RCS), makes individual detection challenging for any radar network. Typical entomological radars work at the X-band (9.4 GHz) with a vertical pencil beam. The measured RCS can be used to estimate insect mass and wingbeat frequency, and then migratory insects can be categorized into broad taxon classes using the estimated parameters. However, current entomological radars cannot achieve species identification with any higher precision or confidence. The limited frequency range of current insect radars have precluded the acquisition of more information useful for the identification of individual insects. In this paper, we report an improved measurement method of insect mass and body length using a radar with many more measurement frequencies than current entomological radars. The insect mass and body length can be extracted from the multi-frequency RCSs with uncertainties of 16.31% and 10.74%, respectively. The estimation of the thorax width and aspect ratio can also be achieved with uncertainties of 13.37% and 7.99%, respectively. Furthermore, by analyzing the statistical data of 5532 insects representing 23 species in East China, we found that the correct identification probabilities exceed 0.5 for all of the 23 species and are higher than 0.8 for 15 of the 23 species under the achievable measurement precision of the proposed technique. These findings provide promising improvements of individual parameter measurement for entomological radars and imply a possibility of species identification with higher precision.

Highlights

Animal migration is increasingly recognized to have ecological effects on both habitats and ecosystems by transport effects and trophic effects [1,2,3]
Researchers in entomology have built various kinds of entomological radars, including airborne entomological radar [12,13], scanning entomological radar [14], tracking entomological radar [15] and vertical-looking radar (VLR) [16,17,18]. Among these radars, scanning entomological radar and vertical entomological radar are the most widely used in the research of insect migration, which have greatly promoted the development of radar entomology
Since the late 2000s, radar-led research has refined our knowledge of the strategies and sensory capabilities employed by migratory insects in flight at night such as navigation, aggregation and orientation [19,20,21]

Summary

Introduction

Animal migration is increasingly recognized to have ecological effects on both habitats and ecosystems by transport effects and trophic effects [1,2,3]. Many tools and techniques, including aerial net sampling and searchlight trapping have been applied [9,10]. In contrast to these traditional monitoring tools and techniques, radars have the advantages of a long detection range and the capability for continuous observation [1,11]. Researchers in entomology have built various kinds of entomological radars, including airborne entomological radar [12,13], scanning entomological radar [14], tracking entomological radar [15] and vertical-looking radar (VLR) [16,17,18] Among these radars, scanning entomological radar and vertical entomological radar are the most widely used in the research of insect migration, which have greatly promoted the development of radar entomology. Since the late 2000s, radar-led research has refined our knowledge of the strategies and sensory capabilities employed by migratory insects in flight at night such as navigation, aggregation and orientation [19,20,21]

Methods

Findings

Discussion

Conclusion