Eucalyptus dundasii Maiden essential oil, chemical composition and insecticidal values against Rhyzopertha dominica (F.) and Oryzaephilus surinamensis (L.)

Abstract

The insecticidal effects of Eucalyptus dundasii Maiden essential oil was studied on the adults of the lesser grain borer, Rhyzopertha dominica (F.), and the saw-toothed grain beetle, Oryzaephilus surinamensis (L.). Essential oil was obtained by the hydro-distillation method and essential oil composition was analysed by GC-MS. Chemical analysis indicated that 1,8-cineole (54.15%), p-cymene (12.41%), α-thujene (11.37%), and E-caryophyllene (6.7%) were major constituents. For R. dominica and O. surinamensis, the LC50 of E. dundasii essential oil was 41.69 and 57.92 μl · l-1 of air, respectively. Increasing the concentration of the essential oil and the exposure time, increased mortality. The durability of fumigant toxicity on O. surinamensis adults was higher than on R. dominica adults and was statistically different. Based on the mean of the repellent indexes and the standard deviation, E. dundasii essence was repellent for both insects at 70, 140, and 280 μl · l-1 of air concentrations. Statistical analysis showed that Relative Growth Rate (RGR) in O. surinamensis was higher than in R. dominica, and the Relative Consumption Rate (RCR), the Efficiency of Conversion of Ingested food (ECI), and the Feeding Deterrence Index (FDI) in O. surinamensis was lower than in R. dominica. The many diverse bio-effects of E. dundasii essential oil confirmed that it is a good candidate for management of R. dominica and O. surinamensis.