The generalist insect herbivore, Icerya seychellarum (Westwood) heavily infests mango trees (Mangifera indica) and can complete its entire life cycle on this plant. However, we observed that mango cultivars are not equally susceptible to I. seychellarum infestation. While mango trees of Sultani cv are heavily infested and severely damaged, trees of Alphonso cv are completely free of I. seychellarum infestation. Comparison between the two cultivars leaves and their total extracts in chemotaxis, feeding and toxicity assays revealed that leaf material of Alphonso cv. contained I. .ychellarum repellant, feeding deterrent and toxic substance. The leaf components of secondary metabolites were screened using solvent/solvent extraction technique followed by gas chromatographic/mass spectrometric (GC-MS) analysis to determine which compound(s) best explained the repellent and toxic properties of Alphonso mango cv. The results suggested that p­cymene, camphene, and limonene play an important role in resistance of Alphonso mango cv. to I. seychel/arum infestation.