Assessing chemical communication in elephants

The study of chemical communication in elephants has resulted in startling and exciting new discoveries in the past decade (Rasmussen and Schulte, 1998; Rasmussen et al., 2003). To date, the highlight of this research has been the identification of two compounds that serve as pheromones (as defined by Karlson and Luscher, 1959). Rasmussen et al. (1996, 1997) identified (Z)-7-dodecen-1-yl acetate (Z7-12:Ac) in female Asian elephant urine collected during the pre-ovulatory period. This estrous pheromone signals approaching ovulation to conspecific males but elicits little interest from female conspecifics. The compound is not unique to elephants; Z7-12:Ac is a component of the mating pheromones for numerous lepidopteran species. More recently, Rasmussen and Greenwood (2003) isolated frontalin, a known aggregation pheromone in bark beetles (Kinzer et al., 1969), from male Asian elephant temporal gland secretion. Male and female Asian elephants exhibit a range of behaviors when exposed to frontalin. The responses depend on the age, sex, and status of the receiver. Male Asian elephants release temporal gland secretion profusely only during musth (Jainudeen et al., 1972a,b), suggesting that frontalin carries a musth-alerting message. Thus, two single compounds, likely acting in conjunction with other chemical components such as proteins (Lazar et al., 2002), mediate sexual and social interactions among Asian elephants.