Aerial detection of nymphal bands of the Australian plague locust ( Chortoicetes terminifera (Walker)) (Orthoptera: Acrididae)

Abstract

The ability to detect nymphal bands quickly from an aircraft flying overhead is critical to the success of preventive control programmes against the Australian plague locust. Ground and aerial observations of bands over a 20-year period have revealed that marching bands, at least 30 m long with a dense front, are visible from an aircraft flying at a height of 300–500 m above ground level. Sustained marching and band visibility are highly temperature dependent and were generally limited to mid-morning to mid-afternoon (0900–1600 h), though on hot days the period was shorter (0800–1100 h). Bands were not visible when it was cool or cloudy. Bands are more visible when nymphs are in the 2nd–4th instars and when vegetation is green as the dark band of feeding nymphs contrasts with the uneaten green vegetation ahead of the band. Overall, only medium to large bands with dense fronts were visible from an aircraft. The findings have enabled the development of operational guidelines for more effective aerial surveys for band detection.