Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 11, 2005
Publication Date: August 1, 2005
Citation: Soroka, J.J., Bartelt, R.J., Zilkowski, B.W., Cosse, A.A. 2005. Responses of flea beetle Phyllotreta cruciferae in the field to synthetic aggregation pheromone components and plant host volatiles. Journal of Chemical Ecology. 31(8):1820-1843. Interpretive Summary: The crucifer flea beetle (Phyllotreta cruciferae) is a major pest of canola and rapeseed in the northern Great Plains, and new pest management tools are needed so that insecticide use can be reduced. It was learned previously that the male beetles produce a pheromone that is attractive to both sexes. Six male-specific compounds were subsequently identified at NCAUR that were believed likely to constitute the pheromone, and chemical syntheses were devised. The present research verified that the compounds do have pheromonal activity in the field, which is a crucial step in the development of this new pheromone. Furthermore, the effect of the synthetic pheromone was found to be enhanced by a chemical from the host plant, called allyl isothiocyanate. This sort of enhancement (synergism) is a common phenomenon with male-produced beetle pheromones. The present study is the first to demonstrate attraction in the field to a synthetic pheromone for any species of flea beetle (a large group of agriculturally important insects). This basic research will be of particular interest to scientists studying the biology and pheromonal communication of these and other beetle species and is a crucial step toward potential development of the pheromone as a pest management tool useful to growers to enhance crucifer crop production.
Technical Abstract: Male-specific compounds, previously identified and synthesized from Phyllotreta cruciferae were demonstrated to be attractive in field trials to both sexes of the beetle, and therefore, are concluded to function in nature as components of a male-produced aggregation pheromone. Six field experiments of 7 to 10 days' duration each were conducted over two years, using a modified boll weevil trap and two doses of pheromone. Treatments containing two doses of allyl isothiocyanate (AITC), a breakdown product of glucosinolates in Brassica napus L., a host plant attractive to the beetles, were also included in the study. Combinations of the pheromone and AITC attracted greater numbers of flea beetles than either component itself. A dose response was observed for both the pheromone and AITC.