|Campbell, James - Jim|
Submitted to: Naturwissenschaften
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2011
Publication Date: 8/17/2011
Publication URL: http://ddr.nal.usda.gov/bitstream/10113/50413/1/IND44619123.pdf
Citation: Lu, Y., Beeman, R.W., Campbell, J.F., Park, Y., Aikins, M.J., Mori, K., Akasaka, K., Tamogami, S., Phillips, T.W. 2011. Anatomical localization and stereoisomeric composition of Tribolium castaneum aggregation pheromones. Naturwissenschaften. 98:755-761. http://dx.doi.org/10.1007/s00114-011-0824-x. Interpretive Summary: Pheromone lures are important tools for both monitoring and control of pest insect populations. Although the commercially produced pheromone "Tribolure" has long been used for monitoring of populations of flour beetles, no one has ever determined either the site of production in the insect body or the natural blend of components in the attractant actually produced by the insect, and there is evidence that the commercial blend is not optimized for maximum attractive potency. In this work, we showed that the natural pheromone is produced in the outer layer of the abdomen, and we determined the composition of the natural blend of the pheromone. We also demonstrated that this natural blend is significantly more attractive than commercial Tribolure. These results could lead to significant improvements in flour beetle detection in mills and warehouses.
Technical Abstract: We report that the abdomen and associated tissues are the predominant sources of male-produced pheromones in the red flour beetle, Tribolium castaneum, and for the first time describe the stereoisomeric composition of the natural blend of isomers of the aggregation pheromone 4,8-dimethyldecanal (DMD) in this important pest species. Quantitative analyses via GC-MS showed that the average amount of DMD released daily by single feeding males of T. castaneum was 878±72 ng (SE). Analysis of different body parts found the abdominal epidermis as the major source of aggregation pheromone; the thorax was a minor source, while no DMD was detectable in the head. No internal organs or obvious male-specific glands were associated with pheromone deposition. Complete separation of all four stereoisomers of DMD was achieved following oxidation to the corresponding acid, derivatization with (1R, 2R)- and (1S, 2S)-2-(anthracene-2,3-dicarboximido)cyclohexanol to diastereomeric esters, and their separation on reversed phase HPLC at –54°C. Analysis of the hexane eluate from Porapak-Q-collected volatiles from feeding males revealed the presence of all four isomers (4R,8R):(4R,8S):(4S,8R):(4S,8S) at a ratio of approximately 4:4:1:1. A walking orientation bioassay in a wind tunnel with various blends of the four synthetic isomers further indicated that the attractive potency of the reconstituted natural blend of 4:4:1:1 was equivalent to that of the natural pheromone, and greater than that of the 1:1 blend of (4R,8R):(4R,8S) used in commercial lures.