*Asawalam EF and U. Igwe

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1 Agricultural Science Research Journals Vol. 2(9), pp , September 2012 Available online at ISSN-L: International Research Journals Full Length Research Paper Insecticidal potentials of curcuma longa l. rhizomes and cymbopogon citratus leaves extracts against the khapra beetle (trogoderma granarium everts.) (coleoptera dermestidae) on stored groundnut *Asawalam EF and U. Igwe Department of Plant Health Management Michael Okpara University of Agriculture, Umudike P.M.B 7267 Umuahia, Abia State, Nigeria. *Corresponding Author s elechiasw@yahoo.com ABSTRACT A laboratory study was conducted to determine the efficacy of Curcuma longa rhizomes and Cymbopogon citratus leaves extracted with different organic solvents (petroleum ether, hexane, methanol and acetone) for the control of Trogoderma granarium Everts. The experimental design was a completely randomized design with four replications. The efficacy of the extracts of these botanicals was assessed under laboratory conditions at room temperature for their biological activities against T. granarium (Kharpra beetle) in stored groundnut seeds. 0.3% of the extracted essential oils were mixed with 50g of the groundnut seeds which were put in plastic vials. The effects of the treatments on insect mortality and adult emergence were assessed. All the treatments with the essential oil showed significant levels of toxicities to the insects. Petroleum ether extract of lemongrass showed the highest mortality amongst the lemongrass extracts while the treatment of turmeric extracted with methanol recorded the highest mortality out of the turmeric extracts. Significantly higher number of adults emerged (10.00%) in the control when compared with the other treatments. This study showed that these essential oils can serve as a means of conserving groundnut seeds. The use of turmeric and lemon grass is recommended for the control of T. granarium in stored groundnut. Key words: plant extracts, essential oil, T. granarium, groundnut seeds, bioactivity. INTRODUCTION Groundnut, Arachis hypogaea L. is a legume belonging to the family Fabaceae. It is an important oil crop of Brazil origin and is cultivated in tropical and warm temperate climates (Musa et al., 2009). As an important oil seed, it accounts for more than one-third of the total oilseeds (Sahayara and Martin, 2003). It is not only rich in protein which is easily digestible and consequently, a higher biological value coupled with its ability to fix nitrogen, it is also rich in B-complex vitamins (Musa et al., 2009). It is an important item in several confectionary products, and in supplementary feeding programs such as in weaning food formulations, in combination with cereals and pulses in many developing countries (Pillari et al., 1984). Various cultivars of groundnut tested in Andra Pradeshsouthern India have shown high content of vitamins K, Phosphorus and potassium. EIegbene (1998) reported that the principle use of groundnut is in the production of oil. Musa et al. (2010) reported that groundnut oil is also used in soap making, and manufacturing of cosmetics and lubricants. The kernels are also eaten raw, roasted or sweetened. They are rich source of protein and vitamins A, B and B 2 groups. Their calorific value is about

2 Asawalam and Igwe per 100 grams and is source of foreign income through export. The residual oil cake contains 7-8 % of Nitrogen, 1.5% of phosphorus and 1.2% of K 2 O as such, it is used as fertilizer. It is also an important protein supplement in cattle and poultry rations. The cake is often used for the manufacture of artificial fiber. The plant stalk (green, dried or silage) are used to feed livestock. Being a legume with root nodules, it can synthesize atmospheric nitrogen and therefore improves soil fertility. However the production and preservation of this crop is greatly constrained by Khapra beetle (Trogoderma granarium Everts. In addition to direct losses caused by secondary feeding, infestation is often followed by colonization by secondary insect pests especially Ephestia cautella Walker and fungi (Aspergillus flavus L.) This consequently leads to deterioration in grain characteristics (El-Nadi, 2001). The insect also contaminate the produce with their moulds and frass. Oil extracted from infested groundnut is also contaminated. Adult T. granarium do not feed but their larvae voraciously feed and cause heavy contamination to the stored product through mass webbing and frass (Musa et al. 2010). Khapra beetle is frequently intercepted on obvious food products such as rice, peanuts, dried animal skins, as well as its preferred natural foods such as wheat and malted barley. Several methods of insect pest control have been employed against this notorious insect pest of stored oil seeds and processed cereal products in Nigeria. According to Redlinger et al., (1988), the efficient and effective control of storage insects like T. granarium has centered mainly on the use of synthetic insecticides. However, many problems are associated with these chemicals such as the development of insect resistance, high mammalian toxicity, high level of persistence in the environment and health hazards to workers (Asawalam et al., 2006). These problems have necessitated search for alternative eco-friendly insect pest control methods amongst which are the use of botanical insecticides. Kabera et al. (2011) observed that the essential oils of Pelargonium graveolens and C. citratus recorded 100% mortality on S. zeamais. Makanjuola (1989) observed that aqueous extracts of neem oil, neem kernel powder and neem press cake were effective against the Khapra beetle. Nadra (2004) reported that powders prepared from parts of eleven different plant species were effective against T. granarium adult and larvae. Dwivedi and Bajaj (2000) reported the repellent activities of Cassia leaf extracts against Khapra beetle. Turmeric is a low growing shrubby species in the family Zingiberaceae. The rhizomes are used in the treatment of menstrual disorders, rheumatism etc in Asia. It contains protein (6.3%), fat (5.1%), minerals (3.5%), carbohydrate (69.4%) and moisture (13.1%). The essential oil (5.8%) obtained by steam distillation of rhizomes has a-phellandrene (1%), sabinene (0.6%), cineol (1%), borneol (0.5%), zingiberene (25%) and sesqurterpines (53%) Curcumin (diferuloylmethane) (34%) is responsible for the yellow colour, and comprises curcumin I (94%), curcumin II (6%) and curcumin III (0.3%) (Bhardwaj et al., 2011). Lemongrass is grown as pot herbs for local medicines and exists in a diversity of forms and cultivars (Rachel, 2011). Jilani, et al. (1988) observed the repellent and growth-inhibiting effects of the essential oil of Turmeric on rust red flour beetle. The objective of this study was to evaluate the efficacy of methanol, acetone, hexane and petroleum ether extracts of Turmeric (Curcuma longa) and Lemon grass (Cymbopogon citratus) against T. granarium (Khapra beetle). MATERIALS AND METHODS Insect culture Adults T. granarium (1:1) were obtained from existing culture in Crop Science Laboratory of Michael Okpara University of Agriculture Umudike Nigeria. The insects were maintained on a groundnut variety (RRB) kept in a Kilner jar (250 ml) fitted with wire-mesh cap to allow aeration and prevent entry of other insects. All live and dead insects were removed two weeks after infestation while emerging larvae were used for the experiment. The culture was raised in a 5 liter plastic container covered with a muslin cloth and held by the side with an expansible rubber band to allow for aeration and avoid suffocation of the insects and equally prevent escape of the insects. The experiment was carried out in the Crop Science Laboratory of Michael Okpara University of Agriculture Umudike under room temperature. Plant collection and extraction of oil Turmeric (C. longa) rhizomes were obtained from the National Root Crop Research Institute Umudike while Lemongrass (C. citratus) was obtained from Umudike farmland. They were shade dried for 4 days. They were both milled using Thomas (model Ed 5) milling machine. The extraction of the essential oil was carried out at Food Technology Laboratory of Michael Okpara University of Agriculture Umudike using soxhlent extractor apparatus and hexane, petroleum ether, acetone and methanol as extract ants. 700g of the milled materials were poured into a 1liter plastic container and 800ml of the respective solvents were added to each of the milled materials and then covered with an aluminum foil. They were allowed for 7 days before being sieved using a plastic sieve and a muslin cloth inside it. This is known as cold extraction and it is necessary to help the respective solvents absorb the oil content of the turmeric and the lemongrass such that when subjected to soxhlet extraction, the essential oil could easily be obtained. The essential oils obtained through soxhlet extraction were stored in amber coloured vials and kept in a refrigerator until when needed.

3 536 Agric. Sci. Res. J. Turmeric extracts yielded 6mls of the oil while lemon grass extract yielded 5 mls of the oil. Bioassays The extracted plant materials obtained from the different solvents was mixed separately with 50g of groundnut in plastic vials at the rate of 150mg per 50g of grain (0.3%) dissolved in 2ml of the solvents and stirred thoroughly with a glass rod for 5minutes to ensure uniform distribution on the seed surface. The treated seeds were allowed for 2 minutes for the solvents to evaporate completely before bioassay. Two sets of control consisting of untreated seeds as well as control of all the solvents were maintained during the study. Ten (10) freshly emerged weevils 5-7 day old of T. granarium were introduced into the plastic vials containing the different treated and untreated groundnut seeds by means of a pooter. The lid of the plastic vial was perforated with hot iron and muslin cloths tightly held with a rubber band was used to secure the opening of the plastic vials to ensure aeration and avoid suffocation. Each treatment was replicated four times and the experiment was arranged in a Completely Randomized Design. Effects of essential oils on mortality Number of dead insects in each vial was counted at 35 days after treatment to estimate T. granarium mortality as: 100 (Number of dead insects) / (Total number of insect) Data on percentage adult weevil mortality were corrected using the formula: P T = (P o P c ) / (100 - P c ) Where P T = Corrected mortality (%) P O = Observed mortality (%) P C = Control mortality (%) Effects of essential oils on adult emergence In a similar experiment, 10 pairs of adult T. granarium were introduced into treated and untreated grains. After 30 days oviposition period, parent adults were removed. Insects subsequently emerging were counted to estimate F I progeny production at 35 days after treatment. Statistical analysis The data obtained were subjected to analysis of variance (ANOVA) procedure for a Completely Randomized Design. Significant means were separated by using Fishers Protected Least Significant Difference (F-LSD). RESULTS AND DISCUSSION Table 1 shows the effect of different solvent extracts of C. longa rhizome extract on percentage adult mortality and adult emergence of T. granarium at 35 days after treatment. The result showed that higher numbers of adult T. granarium mortality were recorded on groundnut seeds treated with different solvent extracts than with the control treatment. There was however no significant difference (P>0.05) between the adult mortality on groundnut seeds treated with acetone, hexane and methanol extracts of C. longa. The result obtained (Table 1) also showed that adult emergence was significantly reduced in the different solvent extracts of C. longa rhizomes than the control. However, there was however no significant difference in adult emergence of T. granarium between the different solvent extracts of C. longa rhizomes. Table 2 shows the effect of C. citratus leaves extract on percentage adult mortality and adult emergence of T. granarium at 35 days after treatment. Result obtained showed that there was significantly higher mortality of T. granarium from groundnut seeds treated with the various solvent extracts of C. citratus leaves compared to the control (0.91%). Pet- ether extract of C. citratus recorded the highest percentage mortality (35.62%) which was significantly different from acetone extract but not significantly different from hexane and methanol extract of C. citratus. The result also showed that higher number of adult T. granarium emerged from groundnut seeds that were not treated with any C. citratus extract (10.00) compared to the groundnut seeds treated with different solvent extracts of C. citratus. There was no significant difference between the acetone, methanol and Pet- ether extracts of C. citratus (Table 2). The result of this study showed that C. longa rhizomes extract and C. citratus leaves extract caused adult mortality. This could be attributed to direct contact of the plant extracts with the beetle. This is in agreement with the work of Kabera et al. (2011) observed that the essential oils of Pelargonium graveolens and C. citratus recorded 100% mortality on S. zeamais. Dike (1992), had earlier reported the efficacy of lemongrass extracts in the control of Callosobruchus maculatus on stored cowpea. Jilani et al. (1988) observed the repellent and growth inhibiting effects of turmeric oil on the rust red flour beetle. Turmeric powders at 5% (w/w) exhibited a significant toxicity of the adult of Rhyzopertha dominica (F.) and Sitophilus oryzae (L.) in stored wheat (Ashouri et al., 2010). Turmeric powder was found to be insecticidal against S. oryzae (Chander et al., 1991). The bioactivity

4 Asawalam and Igwe 537 Table 1. Effect of different solvent extracts of C. longa rhizomes on biological activities of T. granarium at 35 days after treatment (DAT) Treatments Mean % adult mortality Adult emergence Acetone Hexane Methanol Pet- Ether Control L.S.D( 0.05) Table 2. Effect of different solvent extracts of C. citratus leaves on biological activities of T. granarium at 35 days after treatment (DAT) Treatments Mean % adult mortality Adult emergence Acetone Hexane Methanol Pet- ether Contro LSD (0.05) and mode of action of insecticidal- active plant materials are often related to the chemical nature of their biologically active constituents which include fatty acids, phenolics, alkaloids and terpenes (Okunola and Ofuya, 2007). CONCLUSION The result of this study revealed that application of C. longa rhizomes extract and C. citratus leaves extract to stored groundnut against T. granarium was effective and could be exploited as an alternative to synthetic insecticides. It is recommended that methanol can be used to extract the C. longa rhizomes before application on groundnut seeds while hexane or pet- ether can be used to extract the C. citratus leaves for T. granarium control. There is need for further research with these essential oils at varying concentrations to determine the least concentration most effective against the khapra beetle, to aid possible commercial formulations with minimal waste. ACKNOWLEDGEMENT The authors are grateful to Mr. Ifenkwe and Mr. Chukwudi of Food Technology Laboratory, Michael Okpara University of Agriculture Umudike, Nigeria for their assistance with extraction of the essential oils. REFERENCES Asawalam EF, Emosairue SO, Ekeleme F, Wokocha RC (2006). Insecticidal Effect of Powdered Parts of Eight Nigerian Plant Species against Maize Weevils Sitophilus zeamais (Coleoptera: Curculionidae). Nigeria Agricultural Journal 37: Ashouri S, Shayesteh N, Maroufpoor M, Ebadollahi A, Ghasemzadeh S (2010). Toxicity and progeny reduction potency of two powdered spices, turmeric and cinnamon on adults of Rhyzopertha dominica (F.) and Sitophilus granarius (L.). Munis Entomol. Zool., 5, suppl.: Bhardwaj RS, Bhardwaj KS, Ranjeet D, Ganesh N (2011). Curcuma Longa leaves exhibits a potential antioxidant, antibacterial and immunomodulating properties. International J. Phytomed., 3: Chander H, Kulkarni SG, Berry SK (1991). Effectiveness of turmeric powder and mustard oil as protectants in stored milled rice against the rice weevil Sitophilus oryzae. International Pest Control 33: Dike MC, Mbah OI (1992). Evaluation of Lemon Grass, Cymbopogon citratus Staphs. Products in the Control of Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) on Stored Cowpea. Niger. J. Plant Protection. 14: Dwivedi, Bajaj (2000). Repellent Action of Seven Plant Extracts against Trogoderma granarium. Utter Pradesh J. Prints India 5: Elegbene JA (1998). Legumes in: Nutritional Quality of Plant Foods. 1 st Edition, Post Harvest Research Unit. Department of Biochemistry, University of Benin, Benin City, Nigeria. 83pages. El-Nadi AH, Ziaton EA, Doghairi MA (2001). Toxicity of three Plant Extracts to Trogoderma granarium Everts (Coleopteran: Dermestidae). J. Biol. Sci., 4 (12):

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