Abstract:
Species Monarda fistulosa L. (Lamiaceae), which is currently successfully cultivated in the conditions of the Republic of
Moldova, is of great interest due to the content of various components that possess biological activity. Studying the effect
of ethanolic extract and essential oils from M fistulosa in the laboratory conditions showed the presence of ovicidal,
insecticidal, and antifeedant properties against the Colorado potato beetle. Hatching of larvae of L. decemlineata in all
experimental variants was completely suppressed (100 %) in comparison with the control. Essential oils showed higher
insecticidal activity than ethanol extract. The death of the larvae of L. decemlineata in the variant with 5 % ethanol extract
is 13.3 %, and in the variants with essential oils (with and without timoquinone) – 93.3 and 60.0%, respectively. It was
established that the essential oil with thymoquinone has a higher insecticidal properties (by 33.3%) than the oil without
thymoquinone.Mathematical analyses revealed some significant differences of insecticidal activity between variants:
ethanolic extract, essential oils and control (р≤0,05, LSD0.05= 6.7). The larvae in the variants with essential oils did not
feed on the treated leaves of potatoes. In the variant with ethanolic extract treatment (EE), the larvae tried to feed, but the
damage to the leaf plate did not exceed 10 %. In the control the leaves damage was 100 %.
