Acute Oral Mammalian Toxicity and Effect of Solvents on Efficacy ofMaerua edulis(Gilg. & Ben.) De Wolf againstRhipicephalus (Boophilus) decoloratusKoch, 1844 (Acarina: Ixodidae), Tick Larvae

Abstract

Efficacy and toxicity of aqueous and organic solvents extracts of Maerua edulis against ticks and mice, respectively, were determined. Ground leaves were extracted separately using cold water, cold water plus surfactant (1% v/v liquid soap), hot water plus surfactant, hexane, or methanol to make 25% w/v stock solutions from which serial dilutions of 5, 10, 20, and 25% were made. For each concentration, 20 Rhipicephalus decoloratus tick larvae were put in filter papers impregnated with extracts and incubated for 48 h at 27°C and 85–90% RH for mortality observation after 24 h and 48 h. In the toxicity experiment, hot water plus surfactant treatments of 5, 10, 20, and 25% (w/v) M. edulis were administered in suspension per os to sexually mature Balb/C mice and observed for clinical signs and mortality for 72 h. Larvae mortality was highest (>98%) in methanol-extracted M. edulis treatments (20 and 25%), which was not different from the amitraz-based control (Tickbuster®). Mortality was also higher in the hot water than in cold water plus surfactant treatments (P < 0.05). No postadministration adverse health effects were observed in the mice. These results suggest that M. edulis is an effective tick remedy best extracted using methanol or hot water plus surfactant.

Addition of a surfactant to water increases the acaricidal activity of extracts of some plant species used to control ticks by Zimbabwean smallholder farmers

“…After drying, 0.1 g of the residue was dissolved in 1 mL of acetone to make a 10% w/v (or 100 mg/mL) concentration used in the tick bioassays. Previous studies have shown that acetone alone is not toxic or has very low toxicity to tick larvae and other microorganisms and therefore can be used in bioassays [13, 23, 24].…”

“…It has also been shown that solvent-solvent fractionation into different polarity fractions may increase efficacy of plant extracts [14]. Some low-cost measures that can be used include the use of a surfactant and hot water for extraction purposes [15]. In this study, we examined the acaricidal activity of acetone and water extracts with and without a surfactant of different plant species that rural farmers in Zimbabwe use to protect their cattle against ticks.…”

“…The overall objective of the study was to determine the in vitro efficacy of different extractants and fractions of selected plant species against cattle ticks. Based on previous work [15, 16], special attention was given to M. edulis .…”

Novel Agmatine Derivatives in Maerua edulis With Bioactivity Against Callosobruchus maculatus, a Cosmopolitan Storage Insect Pest

“…DeWolf (Capparaceae) is a shrub widely distributed in Southern Africa where it has reported antimicrobial and pesticidal activity ( Nyahangare et al, 2012 , 2017 ; Mazhawidza and Mvumi, 2017 ). To date, however, nothing is known about the components that mediate these reported activities limiting the potential to maximize the pest control benefits of M. edulis for smallholder farmers or understand more about the potential toxicity of the genus ( Malami et al, 2014 ; Nyahangare et al, 2016 ). There are currently a further 13 species of Maerua in southern Africa, ( Swanepoel, 2015 ) so there may be others that have use as botanical pesticides.…”