Fumigant toxicity of essential oils extracted from three plant species against Sithophilus oryzae (L.) (Coleoptera: Curculionidae)

Subject Areas : entomology and othea arthropods

Y.  Motamedi ¹ (Graduated student, Department of Entomology, Jahrom branch, Islamic Azad University, Jahrom, Iran)
M.  Fallahzadeh ² (Department of Entomology, Jahrom branch, Islamic Azad University, Jahrom, Iran)
V.  Roshan ³ (Agricultural and Natural Resource Research Center of Fars, Shiraz, Iran)

Received: 2012-10-03 Accepted : 2013-02-20 Published : 2014-05-22

Keywords:

Abstract :

Over the past few decades, many investigations have been conducted on different plant products in order to obtain safer and more effective alternatives rather than chemical insecticides for controlling store-product insects. For this purpose, in search of alternatives agents for conventional pesticides, the fumigant activity of essential oils from Mentha longifolia L., Tagetes minuta L. and Salvia macrosiphon Boiss. were tested against adult insects of Sitophilus oryzae L. (Coleoptera: Curculionidae) on laboratory condition. The experiment was conducted using a completely randomized design of factorial experiment with five concentrations and three replications at 25±10C, 60±5% R.H in darkness. The results showed that the percentage of mortality was increased with increase in concentration and exposure period. The highest fumigant toxicity was related to M. longifolia and the lowest toxicity was recorded for S. macrosiphon against insects. At the highest concentration of essential oils (25μl/L of air) by M. longifolia, T. minuta and S. macrosiphon the mortality were recorded as 80%, 73.3% and 66.6% after 12h and 96.6%, 86.6% and 73.3% after 24h against S. oryzae, respectively. The LC50 values were evaluated by M. longifoli, T. minuta and S. macrosiphon 8.166, 11.488 and 14.161 μl/L of air after 12h and 5.898, 7.814 and 11.068 μl/L of air after 24h for S. oryzae. According to the results, the essential oils of M. longifolia, T. minuta and S. macrosiphon are source of biologically active vapor that can be used in protection of stored grains against rice weevil.