The effect of contact and respiratory repellency of four medicinal plant extract and powders on adults and last instar larvae of Plodia interpunctella (Hübner)

The indian meal moth is one of the most important pest of stored product. In this study‚ the repellency effect of the alcoholic and hexanic plant extract and powder of four medicinal plants , lavandula angstifolia, artemistia dracunculus, anethum graveolens, and petroselimun sativum have been studied on adults and last instar larvae of this pest. To prepare the extracts, plants were powdered, then dissolved in solvent and filtered after 24 houres. These crude plant extracts have been used in experiments. In contact repellency experiment, the 9 cm whatman filter paper divided into two parts from the middle. Half of it was weted with definite plant extract dose and another half was weted with solvent. after they dried, 20 last instar larvae released from centes each petri dish. then the repellency effect of plant extracts was measured after 24 hours. The results showed all plant extracts except hexanic extract of L. angstifolia, had the contact repellency effect on adult insect. The Y-shaped olfactometer has been used for dtermining fumigant repellency effect of the plant extracts. The repellency effect of treatment were measured on the last instar larvae and adults. In most cases the plant extracts showed a significant repellency effect at1% level on larveae and adults. But the repellency effect of the powders on adults was less than plant extracts, and had attractive effect on, the Indian meal larvae.