In vitro investigation of the toxic effects of extracts of Allium sativum bulbs on adults of Hyalomma marginatum rufipes and Rhipicephalus pulchellus

F Nchu,J.N Eloff,S.R Magano

doi:10.4102/jsava.v76i2.405

Abstract

The toxic effects of the extracts of Allium sativum (Garlic) were evaluated against adults of Hyalomma marginatum rufipes and Rhipicephalus pulchellus using three types (Types A, B and C) of contact toxicity bioassays. A. sativum bulbs were extracted with acetone, ethanol and dichloromethane (DCM) solvents. Among these three solvents, it is the DCM extract of A. sativum that appears to have anti-tick activity. In the Type A contact toxicity bioassay, DCM extracts of A. sativum demonstrated a high acaricidal bioactivity against H. m. rufipes with 100% of ticks killed in less than an hour, and toxicity persisted to the second day. A weak acaricidal activity of aqueous extracts of A. sativum was observed in the Type B contact toxicity bioassay. In the Type C contact toxicity bioassay, a concentration of 24% w/v of DCM extracts of garlic in sunflower oil (Helianthus annuus) had killed 100% of H. m. rufipes (LC50 = 5.9% w/v) and R. pulchellus (LC50 = 10.3% w/v) by 24 hours post-treatment of ticks. The results obtained from this study suggest that DCM extract of A. sativum is a potential source of novel acaricidal agents.

Highlights

Ticks are haematophagous ectoparasites of vertebrates[27] and they play a very important role in the transmission of many disease-causing agents to humans and livestock[5,11,25]
Type C contact toxicity bioassay Data recorded 24 hours following the start of the experiment shows that the mortality of R. pulchellus increased significantly (P < 0.05) with an increase in the concentration of DCM extract of garlic in sunflower oil (Figs 1, 2 ; Table 3)
The results of this study show that the toxicity of the DCM extract of garlic decreased with time and fewer ticks were killed at 48 hours post-preparation of DCM extract (Table 3)

Summary

Introduction

Ticks are haematophagous ectoparasites of vertebrates[27] and they play a very important role in the transmission of many disease-causing agents to humans and livestock[5,11,25]. Tick infestation has been linked to production losses in livestock[22] and to the increase of lifethreatening diseases in humans[23]. The current methods used to control ticks rely largely on the use of acaricides, but, despite their efficacy[7,15], extensive usage has been associated with increased resistance to them[20]. Their uncontrolled use has led to environmental toxicity[2]. Botanical pesticides are said to be biodegradable[16], making them less toxic to the environment and non-targeted species[6]

Methods

Results

Conclusion