Abstract
The Colorado potato beetle feeds only on glycoalkaloid-laden solanaceous plants, appears to be toxic to predators, and has aposematic coloration, suggesting the beetle may sequester alkaloids from its host plants. This study tested 4th instars and adults, as well as isolated hemolymph and excrement, to determine if the beetles sequester, metabolize, or excrete alkaloids ingested from their host plants. HPLC analysis showed: that neither the larvae nor the adults sequestered either solanine or chaconine from potato foliage; that any alkaloids in the beetles were at concentrations well below 1 ppm; and that alkaloids were found in the excrement of larvae at approximately the same concentrations as in foliage. Analysis of alkaloids in the remains of fed-upon leaflet halves plus excreta during 24 hr feeding by 4th instars, as compared to alkaloids in the uneaten halves of the leaflets, showed that equal amounts of alkaloids were excreted as were ingested. The aposematic coloration probably warns of a previously-identified toxic dipeptide instead of a plant-derived alkaloid, as the Colorado potato beetle appears to excrete, rather than sequester or metabolize, the alkaloids from its host plants.
This is a preview of subscription content, log in via an institution to check access.
REFERENCES
Armer C. A. 2003. Entomopathogenic nematodes for biological control of the Colorado potato beetle, Leptinotarsa decemlineata (Say). Doctoral dissertation, Oregon State University.
Armer, C. A., Berry, R. E., Reed, G. L., and Jepsen, S. J. 2004. Colorado potato beetle control by application of the entomopathogenic nematode Heterorhabditis marelata Liu & Berry and potato plant alkaloid manipulation. Entomol. Exp. Appl. in-press.
Brown, M. S., McDonald, G. M., and Friedman, M. 1999. Sampling leaves of young potato (Solanum tuberosum) plants for glycoalkaloid analysis. J. Agric. Food Chem. 47:2331–2334.
Daloze, D., Braekman, J. C., and Pasteels J. M. 1986. A toxic dipeptide from the defense glands of the Colorado beetle. Science 233:221–223.
Deroe, C. and Pasteels, J. M. 1977. Defensive mechanisms against predation in the Colorado beetle (Leptinotarsa decemlineata, Say). Arch. Biol. (Brux.) 88:289–304.
Friedman, M. and McDonald, G. M. 1997. Potato glycoalkaloids: Chemistry, analysis, safety, and plant physiology. Crit. Rev. Plant Sci. 16:55–132.
Hsiao, T. H. and Fraenkel, G. 1969. Properties of Leptinotarsin, a toxic hemolymph protein from the Colorado potato beetle. Toxicon 7:119–130.
Hough-Goldstein, J. A., Geiger J., Chang D., and Saylor W. 1993. Palatability and toxicity of the Colorado potato beetle (Coleoptera: Chrysomelidae) to domestic chickens. Ann. Entomol. Soc. Am. 86:158–164.
Pasteels, J. M., Duffey S., Rowell-Rahier, M. 1990. Toxins in chrysomelid beetles: Possible evolutionary sequence from de novo synthesis to derivation from food-plant chemicals. J. Chem. Ecol. 16:211–222.
Pasteels, J. M., Termonia, A., Windsor, D. M., Witte, L., Theuring, C., and Hartmann, T. 2001. Pyrrolizidine alkaloids and pentacyclic triterpene saponins in the defensive secretions of Platyphora leaf beetles. Chemoecology 11:113–120.
Rothschild, M. 1972. Secondary plant substances and warning colouration in insects, pp. 59–83, in H. F. van Emden (ed.). Royal Entomological Society of London Symposia No. 6: Insect/Plant Relationships. Blackwell Scientific Publications Oxford.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Armer, C.A. Colorado Potato Beetle Toxins Revisited: Evidence the Beetle Does Not Sequester Host Plant Glycoalkaloids. J Chem Ecol 30, 883–888 (2004). https://doi.org/10.1023/B:JOEC.0000028495.26931.c7
Issue Date:
DOI: https://doi.org/10.1023/B:JOEC.0000028495.26931.c7