Radar monitoring unveils migration dynamics of the yellow-spined bamboo locust (Orthoptera: Arcypteridae)

Accurate monitoring of locust migration is the basis for early warning and emergency control programs. This article integrates laboratory recordings with the use of Ku-band vertical insect radar to assess migration of the yellow-spined bamboo locust Ceracris kiangsu (Orthoptera: Arcypteridae) in the China-Laos border area. Under laboratory conditions, field-caught individuals engaged in flight at temperatures above 20℃ and exhibited a wingbeat frequency of 18.5–31.1 Hz. Between July 6 and August 23, 2020, a total of 39C. kiangsu migration events were recorded by radar. Locust individuals only engaged in diurnal migration, with peak activity after 15:00. Flight was recorded at an average height, flight speed and density of 410 m above ground level, 35.8 km/h, and 1305.9 individuals/km3, respectively. High-density C. kiangsu swarms exhibited high flight speeds. Departing from Laos, locusts migrated north by west 27.4–35.0° into Jiangcheng county (Yunnan, China). Migration flight was affected by ambient temperature, while its speed was determined by that of prevailing wind currents. Individual locusts autonomously adjusted their heading direction in order to unify the travel direction of the migrant swarm. Ku-band high-resolution fully polarimetric insect radar can thus accurately assess the migration patterns of C. kiangsu locusts and thereby constitutes an important forecasting tool.