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Abstract
The effect of essential oil (EO) from anise (Pimpinellia anisum) on the mortality of young larvae of Colorado potato beetles has been studied. In our bioassays, P. anisum EO significantly increased the mortality of the second instar larvae of L. decemlineata. Significantly different values of LD 50 and LD90 were established for acute (LD50 = 1.76, and LD90 = 8.29) as well as chronic toxicity (LD50 = 0.45, and LD90 = 1.01). Decrease of both values over experimental period was evident, which showed that the larval mortality was slow and cumulative. The composition of EO used for biological experiments was also assessed. The main component detected in EO from P. anisum was anethole (79.87%), followed by anisaldehyde (7.74%), estragole (5.88%) and [beta]-linalool (1.07%). Within five days, residual concentration of EO decreased from 3.87 mg/g of dry weight immediately after foliar applications to 0.9 mg per g of dry weight. The effect of this slow evaporation could be explained by dominant presence of anethole or by the type of formulation and the addition of oil and tween. Results of our study demonstrate that EO from P. anisum has insecticidal properties that may lead to the development of new organic products for the control of Colorado potato beetles.