The physiological responses of potato plants (Solanum tuberosum), cultivars Cal Red and Russet Burbank, including the production of α-chaconine and α-solanine, glycoalkaloids, were measured at different levels of defoliation by Colorado potato beetles (Leptinotarsa decemlineata). Glycoalkaloids act as acetylcholinesterase inhibitors to both Colorado potato beetles and humans. In a greenhouse and growth room, five replicates of the following treatments- a control, low, medium, high, and manual defoliation- for each variety were arranged in a randomized complete block design. Individual, potted plants served as the experimental units. Approximately 12, 16, and 20 third instars were applied to the low, medium and high treatment plants in cages at the mid flowering stage and allowed to defoliate until they pupated. Tubers were skinned approximately 3mm from the surface and the skin and flesh were separated and freeze dried in a LABCONCO Freeze Dry System/Freezone 4.5 and homogenized. A 25x4.6cm C₁₈ 5ìm solid phase extraction (SPE) column Techsphere 80 (Capital Limited, UK) using an ISCO V⁴ Absorbance Detector (Model 2350) controlled with a DELL OptiPlex G₁ was used for glycoalkaloids analysis of the skin and flesh of the tuber. Results will be presented and related to food toxicity and nutrition and human dietary risk assessment.