Visual 'pinpoint' location associated with pheromonal cue in males of the black chafer Holotrichia loochooana loochooana (Coleoptera: Scarabaeidae)

Abstract

Females of the black chafer Holotrichia loochooana loochooana (Sawada) (Coleoptera: Scarabaeidae) release anthranilic acid, which functions as sex attractant pheromone for males and aggregation pheromone for females. When a white lure treated with anthranilic acid was placed next to an untreated black lure in the field, males were observed to make pinpoint landings significantly more frequently on the latter. When the distance between the two lures was increased from 0 to 20 cm, frequency of pinpoint landing onto the untreated black lures significantly decreased while that onto the treated white lures slightly increased. When the lures were further separated to 2.5-m intervals, males approached only to the treated lures regardless of the color but significantly more frequently landed on the black ones than on the white. These observations demonstrated that males locate and land on a female by visual cues after reaching the vicinity by olfaction.