Isolation, identification and bioassay of repellent factors in the essential oil of pyrethrum for grain protection against Sitophilus zeamais (Molts.).
The repellency of the essential oil of Chrysanthemum cinerariaefolium and identified constituents was evaluated against Sitophilus zeamais in the laboratory. Repellency was measured using a Y-tube olfactometer bioassay. The pyrethrum oil showed a higher repellency against S. zeamais relative to DEET [diethyltoluamide] at all five concentrations tested. Twelve compounds were identified in the C. cinerariaefolium oil by GC and GC-MS. The major components of the oil were trans-β-farnesene, β-cubebene and δ-nerolidol (at 41.36, 17.27 and 14.23%, respectively).