Pheromone identification of<i>Dioryctria abietivorella</i>(Lepidoptera: Pyralidae) from an eastern North American population: geographic variation in pheromone response

Abstract

Abstract The fir coneworm, Dioryctria abietivorella (Groté), is a transcontinental pest of coniferous seed cones. Recently, the attractive pheromone components and lure blend for the fir coneworm in western Canada were identified as a 200 µg : 2000 µg ratio of (9 Z ,11 E )-tetradecadienyl acetate (9 Z ,11 E -14:Ac) and a polyunsaturated hydrocarbon, (3 Z ,6 Z ,9 Z ,12 Z ,15 Z )-pentacosapentaene (C 25 pentaene). A potential third component, ( Z )-9-tetradecenyl acetate (9 Z -14:Ac), which was detected in pheromone gland extracts, had no effect on males of the western population when added to the binary blend. In contrast, in eastern Canada (Quebec) we found that the 200 µg : 2000 µg binary blend was unattractive to male fir coneworms until 9 Z -14:Ac was added. By means of several field experiments we established that a 67 µg : 200 µg : 2000 µg ratio of 9 Z -14:Ac, 9 Z ,11 E -14:Ac, and the C 25 pentaene was attractive to fir coneworms in Quebec. Gas chromatography - mass spectrometry analysis of pheromone gland extracts of fir coneworm from Quebec confirmed the presence of the three components in extracts in an approximately 1 µg : 4 µg : 10 µg ratio of 9 Z -14:Ac, 9 Z ,11 E -14:Ac, and the C 25 pentaene. Our results provide evidence that the eastern and western populations of D. abietivorella are distinct geographic pheromone races, with 9 Z -14:Ac being required for attracting males of the eastern population but not males of the western population.