The potato tuber moth (PTM), Phthoninaea operulella (Zeller) is considered the most serious potato insect pest Varied categories of infestation were observed on different potato cultivars. Potato varieties resistant to insect pests are considered great source of potentiality. Nicola potato cultivar, however was reported as the least performance variety to PTM infestation. Sponta cultivar demonstrates with moderate infestation levels and Arinda cultivar declares the highest level of PTM infestations. The potato plants produced certain metabolic substances that had its role in impediment or made the plants not favorable to the PTM larvae. Phenolic compounds and glutamic acid of the secondary plant metabolites were determined and approved to have certain action on the PTM infestation. The chemical analysis revealed that potato cultivar that demonstrates high content sap of total phenol, high content of conjugated phenol, lowest content of free phenol and lowest content of glutamic acid harbored the least level of PTM infestations. That will give us ideal explanation why Nicola cultivaris considered as the least susceptible in PTM infestations. These circumstances were accomplished with it, and vice versa i.e. Arinda cultivar demonstrates the highest level of PTM infestations. The idea behind this research is to promote biotechnological approaches that can selectively increase the amounts of defense compounds in crop plants, thereby reducing the need for costly and potentially toxic pesticides. Other approach is to promote for importing and/or planting the potato cultivars that perform with good indication of having adequate amounts of these metabolic substances just to minimize the chemical insecticides as far as possible.