Field studies of the efficacy of some commercially available essential oils against horse flies (Diptera: Tabanidae)
Krčmar, Stjepan; Gvozdić, Vlatka
Abstract The repellent activity of commercially available essential oils from the plants Cymbopogon winterianus, Mentha piperita, Litsea citrata and Lavandula angustifolia against female horse flies (Tabanidae) is not yet known, and it was studied in Eastern Croatia. In the absence of standard protocols for determining repellency in field studies, five canopy traps baited with 1-octen-3-ol were used, four of which were protected with essential oils. One canopy trap was always without any essential oil and used as negative control. The chi-square analyses of the trapping data for the canopy traps revealed that the essential oil of Lavandula angustifolia significantly reduced the number of collected horse flies in comparison to those collected in the canopy traps protected with the other essential oils. Significantly less specimens of Tabanus bromius were collected from the canopy traps protected with Lavandula angustifolia when compared with the traps protected with the other essential oils. However, the numbers of females of Tabanus tergestinus and Haematopota pluvialis collected from the canopy traps protected with all four essential oils did not differ significantly. A total of 93.6% of horse flies collected belonged to these three species. Tabanus bromius was the most abundant species with 76.5% in the samples collected by canopy traps. Finally, the traps protected with the essential oil of Lavandula angustifolia collected 0.50 times less horse flies than unprotected traps, whereas traps protected with oils of Mentha piperita, Cymbopogon winterianus, and Litsea citrata collected 0.19, 0.15 and 0.04 times less horse flies, respectively, than did unprotected traps.