A novel mark-recapture technique and its application to monitoring the direction and distance of local movements of rangeland grasshoppers (Orthoptera: Acrididae) in the context of pest management.
Rangeland grasshopper movement was studied in Wyoming, USA, in July 1997 with respect to the biological and ecological factors (population density, developmental stage and weather) influencing net displacement and directionality. A novel adaptation of the mark-recapture method was developed to monitor grasshopper dispersal. The method used fluorescent powder and resighting marked grasshoppers in the field with ultraviolet light, rather than physical recapturing of individuals. Rangeland grasshoppers (mainly Melanoplus sanguinipes, Ageneotettix deorum and Aulocara elliotti) exhibited a strong tendency for directional movement. Adult grasshoppers demonstrated a significant tendency for dispersal in a north-westerly direction across a range of population densities (5-8, 10-15 and ≥18 grasshoppers m