Monday, December 11, 2006 - 10:35 AM

Host plant choice in the Colorado potato beetle, Leptinotarsa decemlineata (Say)

Erin Hitchner,, Virginia Tech, 216A Price Hall, Blacksburg, VA, Thomas P. Kuhar, Virginia Tech, Entomology, Eastern Shore AREC, 33446 Research Drive, Painter, VA, and Joseph C. Dickens, USDA-ARS, Bldg 007, Beltsville, MD.

Colorado potato beetle (CPB) is a major pest of potatoes in the United States. Although potato has been identified as the preferred host for CPB, other solanaceous crops such as eggplant, tomato and pepper serve as suitable hosts. Geographically separated populations of CPB have shown intraspecific variation to host species. In order to better understand the mechanisms for host plant choice of CPB in Virginia, field and laboratory choice tests were conducted. Laboratory olfactometer choice tests utilizing field collected CPB showed a preference of potato over both tomato and eggplant foliage, and eggplant over tomato foliage. Field choice tests found significantly more CPB adults, larvae and egg masses on eggplant than on pepper or tomato. Additional field studies with untreated eggplant and potato showed more CPB adults and egg masses on eggplant than on potato. However, eggplant and potato treated with imidacloprid showed no differences in numbers of dead CPB adults or egg masses. Thus, the presence of CPB on plants appears to affect host plant choice. We tested this hypothesis using an imidacloprid treated eggplant or potato plant paired with an untreated eggplant or potato plant covered in a mesh bag containing two male CPB. Significantly more CPB adults were attracted to eggplant with feeding CPB paired with another eggplant than any other treatment combination. In conclusion, Virginia CPB populations showed a preference of eggplant to potato under field conditions, in contrast to laboratory choice tests where CPB preferred potato to eggplant foliage. This indicates that host plant choice in CPB is related to the presence of feeding CPB.

Species 1: Coleoptera Chrysomelidae Leptinotarsa decemlineata (Colorado potato beetle)

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