Fumigant Toxicity of New Formulations Prepared from Artemisia sieberi (Asteraceae) Essential Oil against Sitophilus oryzae (Col.: Curculionidae)

Nowadays, the increased pest resistance to chemical pesticides and the pesticide residues in food, together with the toxic effects of pesticides on mammals and the environment, necessitate the use of newer and safer alternatives for controlling insect pests. The use of encapsulation technology for pesticides formulations has led to increased efficiency and controlled release of these substances. In this study, four formulations containing Artemisia sieberi Besser essential oil based on biodegradable polymers such as polyethylene glycol, starch, glycerol mono stearate, and maltodextrin were prepared as powder and pellet to control the rice weevil, Sitophilus oryzae. Chemical composition of A. sieberi essential oil was determined and 16 components were identified. Cis-thujone, Santolinyl acetate, Trans-thujone, and Camphor were the major components of the oil. These formulations were different in the amount and type of polymers and surfactants. Also, these formulations were combined with a different rotation speed of the homogenizer. In this study, the fumigant toxicity of these formulations was compared with the A. sieberi oil. The experiments were carried out on the adult stage of the rice weevil at 27±1°C, 70±5% RH and in total darkness condition. The results showed that the LC50 value of the essential oil after 72 hours was 11.33 ppm, while the LC50 of formulations 1 to 4 were 47.61, 57.55, 23.94, and 44.66 ppm, respectively. Therefore, encapsulation of plants essential oils as a safe pesticide with slow release and fumigant toxicity can be used in integrated pest managements.