PHEROMONE-BASED ASSORTATIVE MATING IN A BARK BEETLE

Assortative mating based on a courtship signal was investigated by exa mining the relationship between the male-produced pheromone and female preference in the bark beetle, Ips pini. Female preference in respons e to the male-produced pheromone was measured in the held using traps baited with a range of 11 synthetic blends of the two pheromone enanti omers, (+) and (-)ipsdienol. The production of ipsdienol enantiomers w as measured from individual, live-trapped male beetles in the laborato ry. Although there was a significant regression of the blend that male beetles produced and the blend to which they responded, the sex ratio s of beetles responding to different blends of enantiomers in the fiel d did not differ significantly. In a second experiment, male-female pa irs 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 respon se were not correlated with body size, nor was body size correlated in male-female pairs.