Insecticidal effect of microencapsulated rosemary (Rosmarinus officinalis) essential oil on the confused flour beetle, Tribolium confusum

The confused flour beetle is an important stored product pest in the worldwide. At first, the essential oil of the aerial parts of rosemary (Rosmarinus officinalis) was microencapsulated and then its physicochemical properties and fumigant toxicity were investigated on Tribolium confusum, in this study. Insecticidal bioassays were conducted at 27±3°C temperature and 70±5% relative humidity in the dark. Insecticidal effect of the non-formulated and microcapsules of rosemary essential oil was investigated at 115.84, 142.24, 163.28, 187.52 and 203.44 µl/L air after 24 and 72 h exposure time. Our results demonstrated that the fumigant toxicity of microencapsulated essential oil was significantly lower than the non-formulated essential oil. The mortality rate of non-formulated essential oil at the concentration of 203.44 µl/L air reached 76.6 % after 24 h exposure time and increased to 86.6 % after 72 h exposure time. While the mortality rate of microencapsulated essential oil at the same concentration reached 44.9% and 48.3% after 24 and 72 h exposure time, respectively. Our results revealed that the microencapsulation procedure could be a suitable strategy to obtain a controlled release formulation of R. officinalis essential oil as a botanical insecticide.