Collection and quantification of airborne pheromone from individual females of the black chafer Holotrichia loochooana loochooana (Coleoptera: Scarabaeidae): Heterogeneity of feral females in respect to pheromone release

Abstract

Females of the black chafer, Holotrichia loochooana loochooana emit anthranilic acid which attracts males and also induces female aggregation. Such aggregation comprises different groups of females: those settle first and began to release pheromone and the reinforcements that are attracted. To find out the female heterogeneity, it is essential to quantify the airborne pheromone released by individual females. Two methods were established for quantitative analysis of airborne pheromone, anthranilic acid from female individuals: Collection of released pheromone to glass beakers in the laboratory and collection into a portable device equipped with glass-bead in the field. Both approaches were followed with HPLC analyses. In the laboratory, large variations were found both in calling durations [19.4±18.8 min (mean±SD), n=147] and in the amounts of collected pheromone (47.7±63.3 ng). Furthermore, large daily fluctuations were also observed for individual females. In the field, large variations were also found in the quantities of collected pheromone among the individual females ranged from 0.57 to 24.7 ng/2 min [8.9±6.06 ng (mean±SD), n=46]. These results provided evidence of heterogeneity in the feral females with respect to the pheromone release in the field.