Assessment of the larvicidal potential of Momordica Charantia and Eucalyptus Globulus against Rhipicephalus Microplus ticks using the larval packet test

Abstract

The increasing development of acaricide resistance in Rhipicephalus microplus has created a need for alternative and environmentally sustainable approaches to tick control. Plant-derived products containing bioactive compounds may provide useful botanical alternatives to conventional acaricides. The present study evaluated the in vitro larvicidal activity of aqueous leaf extracts of Momordica charantia and Eucalyptus globulus against R. microplus larvae using the Larval Packet Test (LPT). Leaves of both plants were shade-dried, powdered and extracted with water. Approximately 14-day-old larvae obtained from eggs laid by laboratory-maintained engorged female ticks were exposed to extract concentrations of 12.5, 25, 50 and 100 mg/ml for 24 h. Deltamethrin was used as the reference acaricide and distilled water as the untreated control. Mortality increased with increasing extract concentration. M. charantia produced 34.6, 58.2, 84.7 and 100% mortality at 12.5, 25, 50 and 100 mg/ml, respectively, whereas E. globulus produced 26.4, 49.8, 76.5 and 95.8% mortality at the corresponding concentrations. The estimated LC₅₀ and LC₉₅ values for M. charantia were 33.84 and 57.42 mg/ml, respectively, while those for E. globulus were 29.67 and 62.95 mg/ml. Deltamethrin produced complete mortality, while no mortality occurred in the untreated control. Phytochemical screening indicated the presence of alkaloids, flavonoids, tannins, saponins, glycosides, steroids and triterpenoids. The findings demonstrate promising larvicidal activity of both botanical extracts, with M. charantia showing higher observed mortality at the tested concentrations. Further studies on active compounds, formulation, safety and field efficacy are warranted