Effect of Two Plant Essential Oils and the Entomopathogenic Fungus, Lecanicillium muscarium (Zare & Gams) on the Cotton Aphid, Aphis gossypii Glover

Pathogenicity of the fungus, Lecanicillium muscarium (Zare & Gams) and toxicity of essential oils isolated from the medicinal Ajowan, Carum copticum C. B. Clarke, and the Persian cumin, Carum carvi L., were investigated against the cotton aphid, Aphis gossypii Glover, under laboratory conditions. GC-MS analysis of the used essential oils revealed that cuminal (29.13%), gamma-terpinene (20.23%), cymene (20.02%) and phenylbutanol (13.82%) in C. carvi and thymol (52.23%), cymene (20.41%) and gamma-terpinene (12.58%) in the C. copticum were the main components. Essential oil of C. carvi (LC50 value of 13.392 (11.116-16.500)) was more toxic than C. copticum oil. Concentrations of 1 x 10(7) and 1 x 10(6) spore/ml of L. muscarium created (100%) mortality after 4 and 5 days, respectively. Mortality of A. gossypii was considerably increased in the combination of essential oils with pathogenic fungus. Based on the synergistic ratio, observed phenomenon was additive for all essential oils' concentrations. Based on the present results, C. carvi and C. copticum essential oils and the fungus L. muscarium showed a significant efficacy in controlling A. gossypii. Utilization of such natural agents may decline the wide use of harmful synthetic chemicals and their negative side-effects.