Fumigant toxicity of mustard essential oil and its main compound alone and combinations with modified atmosphere treatments against Tribolium confusum du Val., 1863 (Coleoptera: Tenebrionidae)

This study was carried out in 2017 in Entomology Laboratory of Kahramanmaras Sutcu Imam University to determine fumigant toxicity of mustard essential oil and its main compound (allyl isothiocyanate) alone and in combination with high concentration (92%) of CO2 or N-2 to all life stages of Tribolium confusum du Val., 1863 (Coleoptera: Tenebrionidae) was determined. Preliminary bioassay tests indicated that 10 mu l/l of mustard essential oil and allyl isothiocyanate alone resulted in 100% mortality for all life stages of T. confusum without any necessity of CO2 and N-2 combinations. Lethal concentration tests indicated that combinations of mustard essential oil or allyl isothiocyanate with 92% CO2 produced 1.8 to 7.3 times reductions in LC90 values for larvae, pupae and adults of T. confusum. Generally, the combinations of mustard essential oil or allyl isothiocyanate with 92% CO2 were more toxic to larvae, pupae and adults of T. confusum than those in combinations with 92% N-2 as evidenced by significant decrements in their LC50 and LC90 values. It appears that high concentration of CO2 or N-2 might have a synergistic effect on larvae, pupae and adults of T. confusum when exposed together with mustard essential oil or allyl isothiocyanate. In conclusion, this study indicates that combinations of mustard essential oil or its main compound, allyl isothiocyanate with modified atmospheres can be a potential alternative to the most commonly used commercial fumigants, methyl bromide and phosphine.