Synthesis of southern corn root worm pheromone from S-Citronellol and its field evaluation

Authors: THANGAIAH, SUBRAMANIAN - University Of Utah; Webb, Meiling; GANGA, BHAGAVATHY - University Of Kentucky; Chauhan, Kamlesh

Submitted to: Journal of Agricultural Chemistry and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/14/2016
Publication Date: 11/17/2016
Citation: Thangaiah, S., Webb, M.Z., Ganga, B., Chauhan, K.R. 2016. Synthesis of southern corn root worm pheromone from S-Citronellol and its field evaluation. Journal of Agricultural Chemistry and Environment. 5:223-230.

Interpretive Summary: Southern corn rootworm (SCR), is one of the most important agriculture pests, affecting billions of dollars of crop vegetables and cereals worldwide. At present there are limited alternatives to control this pest besides synthetic pesticides. But, because of complexity and availability, novel economical approaches to produce alternative semiochemicals or biopesticides are needed We developed a synthetic approach using natural terpenes as the starting material to produce SCR pheromone in only six steps. This synthetic method is not only economical, but it can be used to develop novel analogues to assess structural activity relationships of this important natural product. This information will be a useful tool for farmers and scientists working towards crop protection in organic farming, as well as for integrated pest management.

Technical Abstract: The southern corn rootworm (SCR), also called as larvae of spotted cucumber beetle has devastating impact on several grass crops such as soybean, sorghum, wheat, cucumber, alfalfa, cucurbits and it is most damaging to corn and peanuts. In recent times there has been tremendous improvement in the pest control through focused research on granular insecticide, genetic modification of plants. On the other hand synthetic insect sex pheromones play important role in managing pest control through “attract and kill” strategy. In our lab we work on developing new synthetic methods for important pheromones in large scale so that we can test them in a controlled field environment at USDA. Recently we have accomplished large scale synthesis of SCR pheromone through an improved strategy in eight simple steps starting from S-Citronellol. The large scale production of this pheromone enabled us to test in the field and thus we will be presenting preliminary results from field evaluation. The present strategy in synthesis takes advantage of existing chiral center of commercially available cheap material S-Citronellol. The key step in our strategy is coupling of two aliphatic units through Wittig reaction to get the basic carbon skeleton. The Wittig salt from a non-functionalized aliphatic bromide followed by Wittig reaction improves the overall yield in this multistep synthesis of this pheromone. The preliminary field evaluation conductes in the Beltsville Agriculture Research Center’s south farm revealed robust attraction of SCR beetles to synthetic pheromone lures. The SCR pheromone lures also attracted a small amount of cucumber beetles in the traps.