Acaricidal efficacy of bitter almond against two tick species, Argas persicus and Haemaphysalis darjeeling – an in vitro study

Use of plant extracts as acaricides for controlling ticks is an essential area of research concerning economic security and environmental health. The aim of this study was to focus on the acaricidal efficacy of bitter almond powder and bitter almond extracts (aqueous and alcoholic) against the nymph and adult stages of two tick species. It was evaluated at five different concentrations (1% to 5%) with bitter almond powder, bitter almond extracts, and alpha-cypermethrin (1 ml/100 ml) at four different exposure times (24, 48, 72, and 96 hours). The effectiveness of bitter almond alcoholic extract was significantly higher than the aqueous extract, and effectiveness was lowest with the powder at all concentrations at different exposure times for both species. Furthermore, aqueous and alcoholic extracts showed a higher mortality rate among both species than alpha-cypermethrin. LC50 value showed that the toxicity level of bitter almond acaricides increased with the longer exposure time and higher concentration. Toxicity level decreased in the order of alcoholic > aqueous > powder on both species. For both species, the highest toxicity level of bitter almond alcoholic extract was shown for the adult than nymph. Therefore, extracts of bitter almond can be used as an excellent acaricidal alternative to alpha-cypermethrin against these two species.