Antifeedant activity of plant extracts on Leptinotarsa decemlineata Say. and Spodoptera littoralis Bois. larvae

Antifeedant activities of methanol extracts obtained from 75 plant species of the Eurasian region were assessed on Spodoptera littoralis and Leptinotarsa decemlineata larvae. Significant differences in antifeedant activity were found in the highest tested dose of 500 μg/cm2, not only among individual extracts but also between both pest species tested.S. littoralis larvae were less sensitive to the extracts, when 43 extracts showed antifeedant activity lower than 50%, and an effectiveness in the range of 50–95% was found in 13 extracts. Out of all tested extracts, only the extracts obtained from the plants Angelica archangelica, Imperatoria ostruthium, Psoralea bituminosa and Vincetoxicum hirundinaria showed antifeedant activity higher than 95%, and their effective doses (ED50) were estimated as 44, 34, 72 and 11 μg/cm2, respectively.L. decemlineata larvae were very sensitive to all the tested extracts. Only 15 extracts showed antifeedant effectiveness lower than 50%. The highest number of extracts (42) showed effectiveness in the range of 50–95%. 23 extracts were chosen for subsequent tests; antifeedant effectiveness higher than 95% was determined for these extracts. Out of 23 extracts, 3 extracts obtained from A. archangelica, Grindelia camporum and Inula auriculata showed the highest effectiveness, when ED50 lower than 1 μg/cm2.