Graduate student: Michelle D. Marko - now Postdoc at the Connecticut Agricultural
Experiment Station
Advisor: Ray Newman
Key Paper: Marko, M. D., R. M. Newman and F. K. Gleason. 2005. Chemically mediated host-plant selection by the milfoil weevil: a freshwater insect-plant interaction. Journal of Chemical Ecology 31 (12): 2857-2876.
Historically, Euhrychiopsis lecontei has fed on Northern watermilfoil, Myriophyllum sibiricum. However, E. lecontei has shifted onto the invasive exotic Eurasian watermilfoil from Northern watermilfoil (Solarz and Newman 1996). In fact, research by Susan Solarz has shown that the weevil exhibits equal preference for the exotic milfoil and the native milfoil when raised on native milfoil, and actually prefers the exotic milfoil when raised on the exotic milfoil (Solarz 1995, Solarz and Newman 1996). Solarz has also shown that a chemical is released from Eurasian watermilfoil that attracts weevils (Solarz 1995).
I am working to isolate the chemical, or chemicals involved in that host range expansion from Northern watermilfoil to Eurasian watermilfoil. A combination of DEAE, reverse-phase High Performance Liquid Chromatography, Atmospheric Pressure Chemical Ionization-Mass spectroscopy and 1H and 13C NMR will be used to identify the primary weevil attractant(s). A qualitative series of bioassay (Y-tube) driven fractionations will be used to determine which chemicals elicit the strongest response by the weevils.
Because herbivore attraction to host plants often involves
a mixture of chemicals, synergistic effects will also be tested
(Harborne 1988). This quantitative information is important in
order to discern the ecological function of the chemical. The
identification of this chemical, or these chemicals, their location
within the plant and seasonal production may be used to promote
better management practices for controlling milfoil.
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| An example of a Y-tube used in fractionations, weevils "select" one of the test substances by swimming up the branch of the tube containing it. |
updated 5/18/06 by Ray Newman