Synergistic effect of some essential oils on toxicity and knockdown effects, against mosquitos, cockroaches and housefly

The toxicity and knockdown effect of Eucalyptus globulus, Rosmarinus officinalis essential oils and their mixed formulation on Periplaneta Americana (L.), Blattella germanica (L.), Supella longipalpa, Culex pipiens, Anopheles stephensi and Musca domestica were evaluated in a series of laboratory experiments. In all bioassay five different doses (0.625, 1.25, 2.5, 5 and 10%) were used by filter paper (cm2) and aerosol (cm3) bioassay methods, all essential oils was toxic to cockroaches, mosquitos and housefly species the lowest and the highest LC50 belong to mixed formulation on B. germanica (LC50 6.1) and E. globulus on P. americana (LC50 27.7) respectively. In continuous exposure experiments, Mortality (LT50) values for cockroaches ranged from 1403.3 min with 0.625% E. globulus (for P. americana) to 2.2 min with 10% mixed formulation for A. stephensi. The KT50 values ranged from 0.1 to 1090.8 min for 10% and 0.625 for mixed formulation and R. officinalis respectively. The mortality after 24 h for mixed formulation was 100% but for single essential oils ranged from 81.5 to 98.3 for P. americana treated with R. officinalis and A. stephensi treated with E. globulus respectively. Studies on persistence of essential oils on impregnated paper revealed that it has more adulticidal activity for longer period at low storage temperature. Gas chromatographic-mass spectrometric analysis of essential oil showed 14 and 16 peaks for E. globules and R. officinalis respectively. α-Pinene (39.8%), 1, 8-Cineole (13.2%), Camphene (9.1%) and Borneol (3.7%) were present in major amounts for R. officinalis and 1,8-Cineole (31.4%), α-Pinene (15.3%), d-Limonene (9.7%) and α-Terpinolen (5.3%) were present in major amounts for E. globulus respectively. Our results showed that two surveyed essential oils has compatible with synergistic effect on various insect species, furthermore it is useful for applying as integrated pest management tool for studied insects management, especially in situations in which conventional insecticides would be inappropriate.