Abstract:
The in vitro acaricidal activity of two concentrations (2.5% and 25%) of Annona muricata (guyabano) ethanolic seed extracts was tested against the dog tick Rhipicephalus sanguineus. Engorged, female brown dog ticks were exposed to distilled water (negative control), Cypermethrin (positive control), 2.5% and 25% guyabano seed extracts using the adult immersion test and were observed daily for mortalities and oviposition. The results show an increasing trend in mortality by the 25% and 2.5% guyabano seed extracts, exhibiting 100% and 93% mortality on the 17th day, as compared with controls, with 71% and 54% mortality, respectively. Despite the observed trend, the 25% and 2.5% guyabano seed extracts were not significantly different from the controls (p=0.271). The calculated 10-day LC50 of guyabano seed extract was at 12%. Mean tick hatching was lowest in the 25% guyabano seed extract group (23.62%) followed by the 2.5% guyabano seed extract group (24.64%) but differences across treatment groups were not statistically significant (p=0.320). It can be concluded that ethanolic seed extracts taken from Annona muricata have potential acaricidal activity. In vivo studies are recommended to assess the acaricidal activity of the extract in relation to various factors and its possible effects on the host.
