Recognition and characterization of migratory movements of Australian plague locusts,Chortoicetes terminifera, with an insect monitoring radar

Abstract

Abstract. Two special purpose insect-detecting radar units have operated in inland eastern Australia, in the region where nocturnal migratory movements of Australian plague locusts Chortoicetes terminifera occur, for over 10 years. The fully automatic radars detect individual insects as they fly directly overhead and "interrogate" them to obtain information about their characters (size, shape, and wing beating) and trajectory (speed, direction, and orientation). The character data allow locusts to be distinguished from most other migrant species. A locust index, calculated from the total count of locust-like targets for a night, provides a simple indication of migration intensity. For nights of heavy migration, the variation of numbers, directions, and speeds with both height and time can be examined. Emigration and immigration events can be distinguished, as can "transmigration," the passage overhead of populations originating elsewhere. Movement distances can be inferred, and broad source and (more tentatively) destination regions are identified. Movements were typically over distances of up to 400 km. Interpretation of radar observations requires judgment, and the present two units provide only partial coverage of the locust infestation area, but their capacity to detect major population movements promptly, and to provide information between necessarily infrequent surveys, has proved valuable. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

The grand challenges of migration ecology that radar aeroecology can help answer

“…First, if pest insects have distinctive characteristics of size, body shape and/or wing-beat characteristics, perhaps combined with a seasonal occurrence, this tends to limit the likelihood of confusion with non-focal species. An example for this are Australian plague locusts Chortoicetes terminifera, for which entomological monitoring radars have provided inputs into the Australian Plague Locust Commission's operational monitoring and forecasting system (Drake andReynolds 2012, Drake andWang 2013). Second, if insects of interest predominate in the airspace over a region, at least during certain seasons or years, it can reasonably be assumed that they are the major component of the biological scatterers detected by radars.…”

Resolving the heading‐direction ambiguity in vertical‐beam radar observations of migrating insects

“…Australian plague locusts, which were relatively plentiful over this year, were identified from the characteristics of their radar returns (Drake & Wang, 2013;Hao, 2016). Australian plague locusts, which were relatively plentiful over this year, were identified from the characteristics of their radar returns (Drake & Wang, 2013;Hao, 2016).…”

“…The radar observation data are from an IMR at Bourke airport (30.0392°S, 145.952°E, 107 m above sea level) and were acquired from September 2010 to April 2011: This period comprises spring (September-November), summer (December-February), and autumn (March-May) of a single insect-flight year. Australian plague locusts, which were relatively plentiful over this year, were identified from the characteristics of their radar returns (Drake & Wang, 2013;Hao, 2016). The radar observations were recorded every night in three periods of ∼8 min during each hour from 18:00 hr to 06:00 hr Australian Eastern Standard Time (AEST = UTC+10 hr; all times in this paper are AEST).…”

Investigating wind effects on insect migration

“…The Air Pollution Model (tapm) [6], developed by the csiro, was used to simulate the wind directions and wind speeds (wind vector W) at the heights the insects were flying. The air speed is derived from the vector subtraction of the radar-observed track vector T and the modelled wind vector W. In the analysis, Australian plague locusts (Chortoicetes terminifera) are classified based on the character of their radar returns [7], and their air speeds are used to estimate the ratio of the wind speed to the insects' air speed for use in the model. Locusts were detected at different times at all the heights that the radar covers.…”