CHAPTER ONEINTRODUCTION
1.1 General Background to the Study
Ticks are obligatory blood-sucking arachnid arthropods infesting a wide variety of animals including mammals, birds, reptiles and amphibians. They are vectors of disease agents (babesia, cowdria, anaplasma, etc) causing anaemia, dermatitis, paralysis, otocariasis as well as loss of production (Schimdt and Roberts, 1989). Two Families of ticks are well known and of veterinary importance, Ixodidae (hard ticks) and Argasidae (soft ticks) (Sonenshine, 1991; Luqman et al., 2007). Ticks are the most important ectoparasites of cattle, causing economic losses in terms of reduced productivity, fertility, diseases and death (Rajput et al., 2006). Besides being haematophagous, they also inflict notable dermatitis, predispose their host to dermatophilosis and other arthropod-borne infestations such as myiasis (Mtshali et al., 2004). Tick control by use of chemical acaricides, is fraught with various problems like residues, environmental pollution and high cost, clearly demanding the need for alternative approaches (Ghosh et al., 2007). Even though many plants extracts with promising acaricidal effects have been reported in literature, the feasibility of many of these extracts for the control of ticks infesting animals in field conditions has not been adequately studied (Rechav and Hay, 1992).
Jatropha curcas (Euphorbiaceae called pinion of India) is a species originating in the Indies and currently widespread in the villages of Tropical Africa (Adjanohoun et al., 1989). J. curcas grows in tropical and subtropical climates across the developing world, and is often cultivated as a hedge crop. It is easy to establish as it grows relatively quickly with high yield (Willis, 1967). It requires minimal water and nutrients, and is able to grow on barren land under harsh
conditions and poor quality or degraded land (Kandpal and Madan, 1995). It is a multipurpose, drought resistant tree and can be cultivated in areas of low rainfall (Pratt et al., 2002). J. curcas Linn is the commonest specie found in Nigeria, but many species exist in different parts of the world. Oil from its seeds has been found useful for veterinary and medicinal purposes as insecticide, for soap production and as a fuel substitute (Gubitz et al., 1999). Names used to describe the plant vary per region or country. It is most commonly known as ―physic nut. In Mali it is known as ―pourghere, ―bagani in Ivory Coast and it is known as ―tabanani in Senegal. In Tanzania it is known as ―makaen/―mmbono (Fact Foundation, 2006). In Nigeria it is known as ―binidazugu/cinidazugu and ―lapalapa in Hausa and Yoruba languages, respectively (Blench, 2003 and Blench, 2007).
Jatropha is one of the promising biodiesel plants. Oil from its seeds has been found useful for veterinary and medicinal purposes as insecticide, for soap production and as a fuel substitute (Gubitz et al., 1999). The antimicrobial and larvicidal activities of the leaves of the plant (Kalimuthu et al., 2010; Kalimuthu et al., 2011), stem bark (Igbinosa et al., 2009) and the insecticidal property (Adebowale and Adedire, 2006) of the J. curcas seed oil have been reported. Reports on the acaricidal activity of essential oils from various plants against ticks like Boophilus annulatus (Pirali-Kheirabadi and Teixeira da Silva, 2011) and B. microplushave been documented (Gazim et al., 2011). However, there are only few reports on acaricidal properties of J. curcas. Acaricidal activity of crude extracts from stem and leaves of different plants against the cattle ticks were also reported (Madzimure et al., 2011). Jatropha seed is usually toxic when consumed because it contains toxic phorbol esters (Makkar et al., 1998). Thus, alternative use of the seed to derive /extract oil is more appropriate and beneficial than simply exploiting the seed as a food crop. Apart from its use as a biofuel, the Jatropha seed oil is reported to be used to produce soap, medicine and pesticides (Shanker and Dhyani, 2006). Jatropha oil can be used as a fuel formulation in diesel engines directly and by blending it with methanol (Gubitz et al., 1999). The clear seed oil was used as diesel substitute during the World War II (Agarwal and Agarwal, 2007) and these tests conducted at Thailand during WW II.
1.2 Statement of Research Problem
Ticks are the most important ectoparasites of livestock in tropical and sub-tropical areas. Ticks do not only cause direct effect on animals by sucking blood. They are also responsible for the transmission of several important protozoan, rickettsial and viral diseases in man, companion and domestic animals (Soulsby, 1982). Besides their manifested abilities as vectors of disease causing organisms, the direct effects of ticks have substanstial economic importance since they prevent livestock from attaining maximum production (Kocan, 1995). The blood sucking activity of ticks (Ixodidae), irritation and destruction to hides and skins of infested animals, in addition to their role as vectors and intermediate hosts to a number of important protozoan, rickettsial, bacterial and viral diseases are well documented (Authur, 1970), with resultant negative implications on the total energy balance of the animal thereby resulting in decreased productivity (Byford etal., 1992).
Tick-borne diseases were again ranked high in terms of their impact on the livelihood of resource poor farming communities in developing countries (Perry etal., 2002; Minjauw and McLeod, 2003). This is particularly relevant in parts of Sub-Saharan Africa, Asia and Latin America where the demand for livestock products is increasing rapidly (Delgado etal., 1999). Tick bite marks damage the value of hides and skin up to 20–30% (Biswas, 2003). Ticks have also been reported as vectors of infectious agents and zoonotic diseases in humans (Petney et al., 2007). Ticks are routinely controlled by use of chemical acaricideswhich however have serious limitations and cause environmental contamination and destruction to non-target organisms (Garcia-Garcia et al., 2000). These have stimulated research into alternative methods to control ticks by the use of natural products (Graf et al., 2004). The oil is a strong purgative and is used in treating skin ailments and rheumatism (Heller 1996; Marroquin et al., 1997). All parts of the plant have been shown to have insecticidal properties (Grainge and Ahmed, 1988; Consoli et al., 1989; Jain and Trivedi, 1997; Meshram et al., 1994), e.g.against insect/ pests like cotton bollworm, and on pests of pulses, potato and corn (Kaushik and Kumar, 2004). If effective as an acaricide, it may be a potent, eco-friendly vector control alternative.
1.3 Justification
The control of these tick species is therefore paramount if productivity of livestock is to be enhanced (George etal., 1999). Ticks are routinely controlled by the use of chemical acaricides (eg Amitraz®, Flumethrin®, etc). Chemical acaricides cause serious environmental and food chain contaminations, in addition to the development of resistance by some tick species. The use of alternative means of controlling ticks is necessary so as to have a range of compounds with different modes of action to enable the rotational use of these chemicals in the management of existing problems of acaricidal resistance (Rechav and Hay, 1992).
Traditional medicine using plant extracts continues to provide health coverage for over 80% of the world’s population, especially in the developing world (WHO, 2002). All parts of the plant— roots, stems, leaves seeds and fruits—have been widely used in traditional folk medicine in many parts of West Africa (Adamu et al., 2006) and their use for veterinary purposes has been practiced for a long time (Duke, 1985). J. curcas extracts are used in alternative medicine, e.g. acaricidal activity (Dimri and Sharma, 2004), insecticidal properties (Jing et al., 2005; Georges etal., 2008). All parts of the plant have been reported to show insecticidal properties (Grainge and Ahmed, 1988; Consoli et al., 1989; Jain and Trivedi, 1997; Meshram et al., 1994) e.g against insect/ pests like cotton bollworm, and on pests of pulses, potato and corn (Kaushik and Kumar, 2004). Jatropha curcas contains higher steroids, terpenoids (mainly, phorbol ester), flavonoids and alkaloids (mainly, Jatrophine) compounds in the leaf and seed in comparison to other species of Jatropha (Krishnan and Paramathma, 2009). Studies by Makkar et al., 1997 as well as Goel et al., 2007 have indicated that J. curcas seeds extract have a higher concentration of toxic phorbol esters and other compounds than in other parts of the plant including the leaves. Although plant based natural medicines/products are acclaimed to be safe, leading to a rise in it popularity, scientist advocate proper toxicological studies in other to ensure safety of these natural medicines/products before being used because it has been demonstrated that some poisons are also natural (Ansari and Inamdar, 2010). However, much work has not been done on evaluation of acaricidal properties of the seeds of Jatrophacurcas.
1.4 Aim of the Study
The study was aimed at evaluating the in-vitro acaricidal effects of Jatropha curcasmethanolic seed extract on Rhipicephalus (Boophilus) decoloratus ticks and its toxicity on host animals using rabbits as models.
1.5 Objectives of the Study
The following were the objectives of this study:
- determine the phytochemical constituents of the methanol seeds extract of curcas.
- evaluate the effects of different concentrations of the methanol extract on larvae of Rhipicephalus (Boophilus) decoloratus ticks in-vitro.
- determine the effects on hematological, biochemicalparameters and pathological effects on rabbits treated topically with the methanol seed extract of Jatropha curcas
1.6 Research Questions
- Does Jatropha curcas have various phytochemical constituents?
- Does Jatropha curcas methanol seed extract have acaricidal activity on larval stage of Rhipicephalus (Boophilus) decoloratus?
- Do the different concentrations of the methanol seed of Jatropha curcas extract have effect on the larvae of Rhipicephalus (Boophilus) decoloratus ticks in-vitro?
- Does treatment with Jatropha curcas seed extract have effect on hematologic, biochemical parameters and pathology of rabbits?
