Aggregation Pheromone of the Bearded Weevil, Rhinostomus barbirostris (Coleoptera: Curculionidae): Identification, Synthesis, Absolute Configuration and Bioactivity
- 190 Downloads
The bearded weevil, Rhinostomus barbirostris (Coleoptera: Curculionidae: Dryophthorinae), attacks coconut trees, oil palms and other species of Arecaceae. Besides direct damage, R. barbirostris may be a vector of diseases in coconut and oil palms, such as stem bleeding (resinosis) and red ring disease. Currently, the only method to control this weevil is by visual observation of damage and removal of infected plants. Semiochemical-based trapping could improve the effectiveness of monitoring and management of R. barbirostris. In comparisons of volatiles released by R. barbirostris males and females by gas chromatography (GC) two male-specific compounds were observed. GC-mass spectrometry (MS) and GC-Fourier transform-infrared (FTIR) analyses of the natural compounds suggested these were diastereoisomers of 5-hydroxy-4-methylheptan-3-one, also known as sitophilure, a pheromone component of other dryophthorine species. Synthesis of the mixture of all four stereoisomers of sitophilure was performed in two steps, and the chemical structures were confirmed by comparing GC retention times and MS and FTIR spectra of natural and synthetic compounds. The absolute configurations of the two male-specific compounds were elucidated by enantioselective GC; the major component was the (4S,5R)-isomer, and the minor component (4S,5S)-sitophilure. In analyses by GC-electroantennography (EAG) the antennae of male and female R. barbirostris only responded to the (4S,5R)-isomer of the synthetic sitophilure. The stereoisomeric mixture of sitophilure was attractive to both sexes of R. barbirostris in laboratory experiments in the presence of sugar cane volatiles, and a similar result was obtained in a preliminary field trapping test.
KeywordsPalm weevil Semiochemicals Sitophilure Sitophinone 5-hydroxy-4-methylheptan-3-one
We thank the Coordination for Improvement of Higher Education Personnel (CAPES), the State of Bahia Research Foundation (FAPESB) and the National Institute of Science and Technology (INCT) Semiochemicals in Agriculture (CNPq Process 465511/2014-7 and FAPESP Process 2014/50871-0) for supporting research. We also thank Dr. Jeffrey R. Aldrich for his help in improving the English language corrections, and the Professors of the State University of Santa Cruz (UESC), Ivon Lobo and Rosenira Serpa, for assisting the GC-FID analyses, and Rosilene de Oliveira for preliminary GC-MS analyses.
- Coates J (2000) Interpretation of infrared spectra, a practical approach. In: Meyers RA (ed) Encyclopedia of analytical chemistry. John Wiley & Sons Ltd, Chichester, pp 10815–10837Google Scholar
- Ferreira JMS (1987) Proteção fitossanitária do coqueiral. III. Controle de pragas no campo. Empresa Brasileira de Pesquisas Agropecuárias-EMBRAPA, AracajúGoogle Scholar
- Ferreira JMS, Fontes HR (2006) Produção integrada de coco: identificação de pragas, doenças e desordem nutricionais e fisiológicas. Empresa Brasileira de Pesquisas Agropecuárias-EMBRAPA, AracajúGoogle Scholar
- Lubeck AJ, Sutton DL (1983) Kovats retention indices of selected hydrocarbons through C10 on bonded phase fused silica capillaries. J Sep Sci 6:328–332Google Scholar
- Morin J-P, Ps S, Purba RY, Desmier De Chenon R, Kakul T, Laup S, Beaudoin-Ollivier L, Rochat D (2001) A new type of trap for capturing Oryctes rhinoceros (Scarabaeidae, Dynastinae), the main pest in young oil palm and coconut plantings. Brazilian Journal of Agriculture 17:13–22Google Scholar
- Moura JIL (2017) Manejo integrado das pragas das palmeiras. Ceplac/Esmai, Ilhéus. http://www.ceplac.gov.br/paginas/publicacoes/paginas/cartilhas_tecnicas/cartilhas/MIPP.pdf
- Moura JIL, de Oliveira ML, Luz EDMN, Silva SDVM, Santos RS (2013) Weevil associated to gummosis in oil palm (Elaeis guineensis Jacq.) in Brazil. Braz J Agric 88:87–89Google Scholar
- Silverstein RM, Webster FX, Kiemle DJ, Bryce DL (2014) Spectrometric identification of organic compounds. John Wiley & Sons, New YorkGoogle Scholar