Journal of Chemical Ecology

, Volume 20, Issue 10, pp 2687–2703 | Cite as

Comparative analysis of steam distilled floral oils of cacao cultivars (Theobroma cacao L., Sterculiaceae) and attraction of flying insects: Implications for aTheobroma pollination syndrome

  • Allen M. Young
  • David W. Severson
Article

Abstract

Steam-distilled floral fragrance oils from nine distinctive cultivars ofTheobroma cacao L. (Sterculiaceae) in Costa Rica were examined with GC-MS to determine whether or not major differences existed among these cultivars for volatile constituents comprising 50% or more of the samples. The cultivars selected for floral oil analyses were chosen to represent diverse cultivars having supposedly different genetic backgrounds and histories of artificial selection for agronomic purposes. Cluster analysis revealed two major groupings of cultivars: those with higher molecular weight dominant compounds, and those having lower molecular weight compounds. Additionally, one cultivar, Rim-100, selected from criollo or ancestral-type cacao in Mexico and resembling criollo in the appearance of flowers and fruits, formed an extreme group having the highest molecular weight profile for major volatile compounds. Based upon these analyses, bioassays using McPhail traps were performed in an abandoned cacao plantation in northeastern Costa Rica during rainy and dry seasons to determine the relative attraction of these oils to flying insects. Bioassays revealed that the Rim-100 cultivar attracted by far the greatest numbers of cacao-associated midges (Diptera: Ceratopogonidae and Cecidomyiidae), as well as stingless bees (Hymenoptera: Apidae: Meliponinae), suggesting that a floral fragrance having high-molecular-weight volatiles is more potent as an attractant to flying insects than floral oils having lower-molecular-weight compounds. It is suggested that Rim-100 more closely resembles an ancestral or wild-type cacao than the other cultivars examined, and therefore it is more effective in attracting opportunistic dipteran floral visitors and pollinators than other cultivars in plantation settings. Several of the major volatile compounds found in the floral oils ofT. cacao and other species ofTheobroma occur in mandibular and other exocrine glands in various bees, including stingless bees and halictids, known visitors ofTheobroma flowers. These compounds are particularly present in noncultivated species ofTheobroma and have much more noticeable fragrances than the seemingly scentless flowers of cultivatedT. cacao selected for agriculture. It is hypothesized that the floral attraction system of ancestral or wild (noncultivated)T. cacao and other species ofTheobroma may have evolved to attract certain bees as their principal pollinators in natural habitats in the Neotropics, with a floral reward hypothesized as being sociochemicals needed by bees for mating, foraging, territorial defense, etc. Because of the many generations of extensive selection by cloning for desired cultivars,T. cacao might have lost much of its original floral attraction system for bees, instead being pollinated opportunistically by dipterans in plantation habitats. This may help to explain why natural pollination in cultivatedT. cacao is generally very poor relative to observed levels of fruit-set in wild or noncultivated species ofTheobroma.

Key words

Floral oils cacao Theobroma cacao Sterculiaceae attraction Diptera Ceratopogonidae Cecidomyiidae Hymenoptera Apidae pollination 1-pentadecene n-pentadecene 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Aguiar-Falcao, M., andLieras, E. 1983. Aspectos fenologicos, ecologicosce de productividade do cupucao-Theobroma grandflorum (Willd. ex Spreng) Schum.Acta Amazonica 13:725–735.Google Scholar
  2. Allen, J.B. 1982. Collecting wild cocoa in its centre of diversity, pp. 655–662,in Proceedings of the 8th International Cocoa Research Conference, October 1981, Cartegena, Colombia, Stephen Austin, Ltd., London.Google Scholar
  3. Bennett, F.D. 1972. Baited McPhail fruitfly traps to collect euglossine bees.J.N.Y. Entomol. Soc. 80:137–145.Google Scholar
  4. Blum, M.S., Crewe, R.M., Kerr, W.E., Keith, L.H., Garrison, A.W., andWalker, M.M. 1970. Citral in stingless bees: isolation and functions in trail-laying and robbing.J. Insect Physiol. 16:1637–1648.CrossRefPubMedGoogle Scholar
  5. Brew, A.H. 1986. Studies on natural pollination of cocoa. Cocoa Research Institute of Ghana, Annual Reports, 1982/1983–1984/1985, pp. 100–109.Google Scholar
  6. Bystrak, P.G., andWirth, W.W. 1978. The North American species ofForcipomyia, subgenusEuprojoannisia (Diptera: Ceratopogonidae). Technical Bulletin No. 1591, U.S. Department of Agriculture.Google Scholar
  7. Crewe, R.M., andFletcher, D.J.C. 1976. Volatile secretions of two Old World stingless bees.S. Afr. J. Sci. 72:119–120.Google Scholar
  8. Cuatrecasas, J. 1964. Cacao and its allies, a taxonomic revision of the genusTheobroma.Contrib. U.S. Natl. Mus. 35:379–614.Google Scholar
  9. Dessart, P. 1961. Contribution a l'etude des Ceratopogonidae (Diptera).Bull. Agric. Congo Belge 52:525–540.Google Scholar
  10. Duffield, R.M., Wheeler, J.W., andEickwort, G.C. 1984. Sociochemicals of bees, pp. 387–420,in W.J. Bell and R.T. Cardé (eds.). Chemical Ecology of Insects. Sinauer Associates, Sunderland, Massachusetts.Google Scholar
  11. Enriquez, G.A., andSoria, J.V. 1970. Cacao Cultivars Registers. San Jose, Costa Rica: Instituto de Investigaciones de Ciencias Agricola (I.I.C.A.)Google Scholar
  12. Entwhistle, P.F. 1972. Pests of Cocoa. Longmans, London.Google Scholar
  13. Erickson, B.J., Young, A.M., Strand, M.A., andErickson, E.H., Jr. 1987. Pollination biology ofTheobroma andHerrania (Sterculiaceae). II. Analyses of floral oils.Insect Sci. Appl. 8:301–310.Google Scholar
  14. Gabel, B., Thiery, D., Suchy, V., Marion-Poll, F., Hradsky, P., andFarkas, P. 1992. Floral volatiles ofTanacetum vulagre L. attractive toLobesia botrana Den. et Schiff. females.J. Chem. Ecol. 18:693–702.CrossRefGoogle Scholar
  15. Glendenning, D.R. 1962. Natural pollination of cacao.Nature 193:1305.Google Scholar
  16. Hernandez, J. 1965. Insect pollination of cacao (Theobroma cacao L.) in Costa Rica. Unpublished dissertation. University of Wisconsin, Madison, Wisconsin.Google Scholar
  17. Holdridge, L.R. 1966. Life Zone Ecology. Tropical Science Center, San José, Costa Rica.Google Scholar
  18. Ibrahim, A.G., andJussein, A.M. 1987. Role of insects in the pollination of cocoa flowers.Pertanika 10:103–106.Google Scholar
  19. Kaufman, T. 1973. Preliminary observations of cecidomyiid midge and its role as a cocoa pollinator in Ghana.Ghana J. Agric. Sci. 6:1093–1098.Google Scholar
  20. Kaufman, T. 1975a. Biology and behavior of cocoa pollinating Ceratopogonidae in Ghana.Environ. Entomol. 4:347–351.Google Scholar
  21. Kaufman, T. 1975b. An efficient, new cocoa pollinator,Lasioglossum sp. (Hymenoptera: Halictidae) in Ghana, West Africa.Turrialba 25:90–91.Google Scholar
  22. Posnette, A.F. 1944. Pollination of cacao in Trinidad.Trop. Agric. 21:115–118.Google Scholar
  23. SAS Institute. 1990. SAS Language Guide for Personal Computers. SAS Institute, Cary, North Carolina.Google Scholar
  24. Saunders, L.G. 1959. Methods for studyingForcipomyia midges, with special reference to cacaopollinating species (Diptera, Ceratopogonidae).Can. J. Zool. 37:33–51.Google Scholar
  25. Soria, S.de J. 1970. Studies onForcipomyia midges (Diptera, Ceratopogonidae) related to the pollination ofTheobroma cacao L. Unpublished dissertation. University of Wisconsin, Madison, Wisconsin.Google Scholar
  26. Soria, S.de J. 1975. O papel das abelhas sem ferrao (Meliponinae) na pollinizacao o cacaueiro na America tropical.Rev. Theobroma. (Brazil) 5:12–20.Google Scholar
  27. Winder, J.A. 1977. Field observations on Ceratopogonidae and other Diptera: Nematocera associated with cocoa flowers in Brazil.Bull. Entomol. Res. 67:57–63.CrossRefGoogle Scholar
  28. Yamida, M. 1991. Genetic studies in cacao (Theobroma cacao L.). Unpublished dissertation. University of Wisconsin, Madison, Wisconsin.Google Scholar
  29. Young, A.M. 1983. Seasonal differences in abundance and distribution of cacao-pollinating midges in relation to flowering and fruit set between shaded and sunny habitats of the La Lola Cocoa Farm in Costa Rica.J. App. Ecol. 20:801–831.Google Scholar
  30. Young, A.M. 1985a. Studies of cecidomyiid midges (Diptera: Cecidomyiidae) as cocoa pollinators (Theobroma cacao L.) in Central America.Proc. Entomol. Soc. Wash. 87:49–79.Google Scholar
  31. Young, A.M. 1985b. Cocoa pollination.Cocoa Growers' Bull. 37:5–23.Google Scholar
  32. Young, A.M. 1985c. Pollen collecting by stingless bees on cacao flowers.Experientia 41:760–762.CrossRefGoogle Scholar
  33. Young, A.M. 1989a. Comparative attractiveness of floral fragrance oils of “Rim” and “Catongo” cultivars of cacao (Theobroma cacao L.) to Diptera in a Costa Rican cacao plantation.Turrialba 39:137–142.Google Scholar
  34. Young, A.M. 1989b. Pollination biology ofTheobroma andHerrania (Sterculiaceae). IV. Major volatile constituents of steam-distilled floral oils as field attractants to cacao-associated midges (Diptera: Cecidomyiidae and Ceratopogonidae) in Costa Rica.Turrialba 39:454–458.Google Scholar
  35. Young, A.M., Schaller, M., andStrand, M. 1984. Floral nectaries and trichomes in relation to pollination in some species ofTheobroma andHerrania (Sterculiaceae).Am. J. Bot. 71:466–480.Google Scholar
  36. Young, A.M., Erickson, B.J., andErickson, E.H., Jr. 1987a. Steam-distilled floral oils ofTheobroma species (Sterculiaceae) as attractants to flying insects during dry and wet seasons in a Costa Rican cocoa plantation, pp. 289–296,in Proceedings of the 10th International Cocoa Research Conference, Santo Domingo, The Dominican Republic. Stephen Austin, Ltd., London.Google Scholar
  37. Young, A.M., Erickson, E.H., Jr. andErickson, B.J. 1987b. A trap survey of flying insects in “Finca Experimental La Lola” in Costa Rica.Turrialba 37:337–356.Google Scholar
  38. Young, A.M., Erickson, B.J., andErickson, E.H., Jr. 1988. Pollination biology ofTheobroma andHerrania (Sterculiaceae). III. Steam-distilled floral oils ofTheobroma species as attractants to flying insects in a Costa Rican cocoa plantation.Insect Sci. Appl. 10:93–98.Google Scholar

Copyright information

© Plenum Publishing Corporation 1994

Authors and Affiliations

  • Allen M. Young
    • 1
  • David W. Severson
    • 2
  1. 1.Zoology SectionMilwaukee Public MuseumMilwaukee
  2. 2.Department of Animal Health and Biomedical SciencesUniversity of WisconsinMadison

Personalised recommendations