Fumigation Toxicity of Essential Oils from Five Species of Eucalyptus against Adult of Sitophilus Oryzae L. (Coleoptera: Curculionidae)

Rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae) is one of the major and cosmopolitan pests of stored products. This study was conducted to estimate the fumigant toxicity effect of essential oils from five species of Eucalyptus including E. camaldulensis, E. grandis, E. viminalis, E. microtheca and E.sargentii against adults of this pest. Essential oils were prepared by hydro distillation methods using clevenger-type apparatus. Based on primary experiments, for each essential oil, five concentrations in five replications with controls were used. The adult mortality was recorded after 24, 48 and 72 h of treatment. Probit analysis was used to estimate LC50 values by SAS 9.1. Based on the results, the mortality of 1-7 day old adults of the insect pest increased with increasing concentration and exposure time from 24 to 72 h. LC50 values of essential oil of E. camaldulensis, E. grandis, E.viminalis, E. microtheca and E. sargentii on adults of S. oryzae were found to be 17.49, 15.65, 14.73, 11.11 and 11.94 µl/lair, respectively. Results show that after 48 h of fumigation the highest and lowest toxicity was related to the E. microtheca (LC50= 11.11 µl/lair) and E. camaldulensis (LC50=17.49 µl/lair), respectively. It was found that essential oils extracted from Eucalypts species could be used as a safe pesticide or model for new synthetic pesticides to control storage pest.