Pheromone-based assortative mating in a bark beetle

Abstract

Abstract. Assortative mating based on a courtship signal was investigated by examining the relationship between the male-produced pheromone and female preference in the bark beetle, Ips pini. Female preference in response to the male-produced pheromone was measured in the field using traps baited with a range of 11 synthetic blends of the two pheromone enantiomers, (+) and (-)ipsdienol. The production of ipsdienol enantiomers was measured from individual, live-trapped male beetles in the laboratory. Although there was a significant regression of the blend that male beetles produced and the blend to which they responded, the sex ratios of beetles responding to different blends of enantiomers in the field did not differ significantly. In a second experiment, male female pairs were sampled in the field, females were assayed for preference in a laboratory olfactometer, and male enantiomer production was measured in the laboratory. There was a significant correlation between female preference and male blend production. Pheromone production and response were not correlated with body size, nor was body size correlated in male-female pairs.