Chemical Ecology Group

Identifying and understanding the role of chemical signals (semiochemicals)

Chemical ecology deals with chemical mechanisms controlling intra- and inter-specific interactions among living organisms and in particular "semiochemicals" which are the chemical signals that transmit information. Identification of these signals is a major component of the work of the chemical ecology group.

Sophisticated electrophysiological recordings coupled to high resolution gas chromatography give primary identification of semiochemicals from samples of volatiles collected with specialised equipment. The insect antenna is used as a biological detector to identify the active compounds. In this technique, compounds eluting in very narrow bands from a high resolution GC column are presented, in real time, to the electrophysiological preparation allowing active components to be located even in highly complex mixtures. In addition to use of this technology for identifying semiochemicals we are developing applications to detect indicator compounds for biological contamination and deterioration of food.

Coupled Gas Chromatography – Electroantennogram equipment

Electroantennogram trace

Electrophysiologically active compounds are identified using GC-MS and NMR. Behavioural experiments are conducted to determine the biological of chemical signals. Molecular structures for pheromones such as the mosquito oviposition pheromone, aphid sex pheromone, sandfly pheromone, and vine bud moth pheromone have all been identified by us using these approaches.

Publications

Borges, M., Birkett, M., Aldrich, J.R., Oliver, J.E., Chiba, M., Murata, Y., Laumann, R.A., Barrigossi, J.A., Pickett, J.A., Moraes, M.C.B. Sex attractant pheromone from the rice stalk stink bug, Tibraca limbativentris stal (2006) J. Chem. Ecol., 32: 2749-2761.

Birkett, M.A., Chamberlain, K., Khan, Z.R., Pickett, J.A., Toshova, T., Wadhams, L.J., Woodcock, C.M. Electrophysiological responses of the lepidopterous stemborers Chilo partellus and Busseola fusca to volatiles from wild and cultivated host plants (2006) J. Chem. Ecol., 32: 2475-2487.

Gouinguené, S., Pickett, J.A., Wadhams, L.J., Birkett, M.A., Turlings, T.C.J. Antennal electrophysiological responses of three parasitic wasps to caterpillar-induced volatiles from maize (Zea mays mays), cotton (Gossypium herbaceum), and cowpea (Vigna unguiculata) (2005) J. Chem. Ecol., 31: 1023-1038.

Goldansaz, S.H., Dewhirst, S., Birkett, M.A., Hooper, A.M., Smiley, D.W.M., Pickett, J.A., Wadhams, L., McNeil, J.N. Identification of two sex pheromone components of the potato aphid, Macrosiphum euphorbiae (Thomas) (2004) J. Chem. Ecol., 30: 819-834.

Birkett, M.A., Dodds, C.J., Henderson, I.F., Leake, L.D., Pickett, J.A., Selby, M.J., Watson, P. Antifeedant compounds from three species of Apiaceae active against the field slug, Deroceras reticulatum (Muller) (2004) J. Chem. Ecol., 30: 563-576.

Birkett, M.A., Bruce, T.J.A., Martin, J.L., Smart, L.E., Oakley, J., Wadhams, L.J.  Responses of female orange wheat blossom midge, Sitodiplosis mosellana, to wheat panicle volatiles (2004) J. Chem. Ecol., 30: 1319-1328.

Tsanuo, M.K., Hassanali, A., Hooper, A.M., Khan, Z., Kaberia, F., Pickett, J.A., Wadhams, L.J. Isoflavanones from the allelopathic aqueous root exudate of Desmodium uncinatum (2003) Phytochemistry, 64: 265-273.

Hooper, A.M., Donato, B., Woodcock, C.M., Park, J.H., Paul, R.L., Boo, K.S., Hardie, J., Pickett, J.A. Characterization of (1R,4S,4aR,7S,7aR)-dihydronepetalactol as a semiochemical for lacewings, including Chrysopa spp. and Peyerimhoffina gracilis (2002) J. Chem. Ecol., 28: 849-864.

Costantini, C., Birkett, M.A., Gibson, G., Ziesmann, J., Sagnon, N.'F., Mohammed, H.A., Coluzzi, M., Pickett, J.A. Electroantennogram and behavioural responses of the malaria vector Anopheles gambiae to human-specific sweat components (2001) Med. Vet. Entomol., 15: 259-266.

Kimani, S.M., Chhabra, S.C., Lwande, W., Khan, Z.R., Hassanali, A., Pickett, J.A. Airborne volatiles from Melinis minutiflora P. Beauv., A non-host plant of the spotted stem borer (2000) J. Ess. Oil Res., 12: 221-224.

Barata, E.N., Pickett, J.A., Wadhams, L.J., Woodcock, C.M., Mustaparta, H. Identification of host and nonhost semiochemicals of eucalyptus woodborer Phoracantha semipunctata by gas chromatography-electroantennography (2000) J. Chem. Ecol., 26: 1877-1895.

Birkett, M.A., Campbell, C.A.M., Chamberlain, K., Guerrieri, E., Hick, A.J., Martin, J.L., Matthes, M., Napier, J.A., Pettersson, J., Pickett, J.A., Poppy, G.M., Pow, E.M., Pye, B.J., Smart, L.E., Wadhams, G.H., Wadhams, L.J., Woodcock, C.M. New roles for cis-jasmone as an insect semiochemical and in plant defense  (2000) PNAS, 97: 9329-9334.