Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 12, 2001
Publication Date: N/A
Interpretive Summary: The Colorado potato beetle (CPB) is a major pest of solanaceous plants in North America, Europe and Asia. Development of resistance in CPB to synthetic pesticides and other control measures has stimulated a search for alternative approaches for control. Although CPB resistance correlates with levels of glycoalkaloids (GA's), a specific class of chemical in foliage of host plants, the mechanism by which GA's are detected and their mode of action has remained a mystery. Here we report our discovery of taste nerve cells in adult CPB that respond specifically to the glycoalkaloid, leptine I, a chemical correlated with CPB resistance in potatoes and their relatives. These identifiable taste nerve cells can be used by entomologists to evaluate potential feeding deterrents as components of integrated management of CPB, and molecular biologists and plant breeders in their efforts to develop plants with increased resistance.
Neurons from chemosensory sensilla on the galeae of adult Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), were investigated for responses to glycoalkaloids of the family Solanaceae. While solanine and tomatine elicited irregular firing by multiple neurons and bursting activity at 1mM concentration in most sensory hairs, stimulation with leptine I resulted in consistently high frequency, phasic-tonic responses with a dose dependent effect between 0.03 and 0.3mM concentrations. Responses to a mixture of solanine and leptine I suggested possible modification of the leptine I response by other glycoalkaloids, resulting in reduced neural activity relative to leptine I alone. These results establish a method for specifically evaluating leptine I and other glycoalkaloids for effects on feeding behavior of CPB, and provide a sensory component for incorporating deterrent chemistry into biorational control methods for the CPB.