New knowledge for yield, composition and insecticidal activity of essential oils obtained from the aerial parts or seeds of fennel (Foeniculum vulgare Mill.)

Abstract

Fennel is an important medicinal and aromatic plant. Essential oils obtained from this plant have found application in various fields, including the production of botanical insecticides. In two seasons, we evaluated the yields of seeds and above-ground biomass, and we monitored the yield rate, chemical composition and insecticidal efficacy of the EOs.We found out that the tested genotype provided a high biomass yield, with two harvests per year; the yield of fresh above-ground biomass was 15.8kg/m2 in the first year, and 14.3kg/m2 in the second year, or 3.3kg/m2 and 3.1kg/m2, respectively, of dry biomass. This biomass could be used to potentially obtain 366.2kg and 317.4kg of EO/ha, respectively, in the first and second year, i.e. an amount statistically significantly higher compared to EOs obtained from seeds (215.3kg and 187.9kg of EO/ha, respectively, for the first and second year).Their analysis detected 7–9 substances (relative contents >0.05%), forming 88.99–98.59% of the EO contents. All EOs contained a majority share of trans-anethole (48.42–63.23%). The highest amount of trans-anethole was found in EOs obtained from seeds (≥60%).All EOs obtained from different biomasses exhibited important insecticidal effects against Culex quinquefasciatus larvae, Spodoptera littoralis larvae and Musca domestica adults.Czech fennel F. vulgare cv. Moravsky is a high-growth genotype that provides a high yield of above-ground biomass; this biomass can be used with a benefit to obtain EOs utilizable for the development and production of botanical insecticides