| Summary: | The aim of this study was to determine the effects of water extracts of tarragon (<i>Artemisia dracunculus</i> L.) on the feeding intensity, mortality, and weight gain of selected pests, i.e., adult pea leaf weevils (<i>Sitona lineatus</i> L.), nymphs, wingless females of black bean aphids (<i>Aphis fabae</i> Scop.), and L2 and L4 larvae of Colorado potato beetle (<i>Leptinotarsa decemlineata</i> Say). In addition, the effect of the tarragon extracts on the voracity of the non-target organism <i>Coccinella septempunctata</i> L. L3 larvae was examined. To reduce <i>S. lineatus</i> feeding, at least 10% dry matter (DM) extract and 20% fresh matter (FM) should be used. Tarragon water extract has strong aphicidal potential against <i>A. fabae</i>, with 84% mortality of nymphs at 30% FM and 78% mortality of wingless females at 10% DM after 108 h of exposure. Aphid nymphs turned out to be more sensitive to the extracts prepared from fresh tarragon than from its dry matter. They were also more sensitive than wingless females. The body weight gain of L2 and L4 larvae of Colorado potato beetle was significantly reduced through the application of 10% and 5% extracts prepared from dry matters, respectively, while extracts prepared from fresh matter turned out to be ineffective. L2 larvae were more susceptible to extracts than L4 larvae, which suggests that they should be used as early as possible in the pest season. No negative influence of the extracts used on the voraciousness of <i>C. septempunctata</i> L3 larvae was found.
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