Abstract
Indian meal moth, Plodia interpunctella Hübner (Pyralidae) is one of the most important stored-product insects that are controlled by fumigants. However, the use of plant essential oils and their constituents may have the advantage over conventional fumigants in terms of low mammalian toxicity and can be used as alternatives to conventional fumigants. Therefore, in this research, repellent activity of 18 plant essential oils was investigated on adults and last instar larvae of Indian meal moth. Also, fumigant toxicity of the essential oils was studied on the first instar larvae. Repellency of the essential oils on adults showed that Anethum graveolens and Rosmarinus officinalis at 2 µliter essential oil in 2 grams food had 100% activity. Hyossopus officinalis and Petroselinum sativum showed the lowest (14.8%) repellency. Consistent with adult repellency, both of R. officinalis and A. graveolens had high repellency on larvae. The fumigant toxicity results of the oils showed that all plants had LC50 values less than 26 µl/l air, indicating strong fumigant toxicity on first instar larvae. Dill was less toxic (LC50= 25.48 µl/l air); while Cinnamomum zeylanicum, Carum carvi, Achillea millefolium and Melissa officinalis were the most toxic with LC50 values of 2.12, 5.06, 5.20 and 5.57 µl/l air, respectively. Consequently, most of these plant essential oils specially Rosemary and Dill may have high potential for using in integrated control of Indian meal moth in storage, in terms of repellency.

Key words: Essential oils, Indian meal moth, Repellency, Fumigant toxicity, Stored product pests