Pheromonal control of the invasive brown treesnake: potency of female sexual attractiveness pheromone varies with ovarian state

The female sex pheromone has potential a s a control tool for the Brown Treesnake, Boiga irregularis Merrem, a pest introduced into Guam. We conducted male-guided bioassays to determine whether potency of the female pheromone varied according to reproductive state and during vitellogenesis. In weekly simultaneous choice tests, we presented males with skin lipid samples from vitellogenic females, non-vitellogenic females, conspecific males, and carrier controls. The total time each sample was tongue-flicked was recorded: mean total tongue-flick time was highest for samples from vitellogenic females followed by samples from non-vitellogenic females. Pair-wise comparisons of male tongue-flick time for samples of non-vitellogenic females versus males and vitellogenic females versus non-vitellogenic females revealed differences in some weeks, but the greatest and most frequent differences were between vitellogenic females versus males. We observed no trend in the potency of the pheromone during vitellogenesis. Pheromone potency was greatest during vitellogenesis, with lesser potency retained while non-reproductive. Efforts at chemical identification of the pheromone and development of control tools should focus on material obtained from vitellogenic females.