Comparative Use of Botanical Oil Extracts in Pest Management Olotuah, O.F

Comparative use of botanical oil extracts in pest management Olotuah, O.F. Department of Plant Science and Biotechnology, Adekunle Ajasin University, P.M.B.001, Akungba – Akoko, Ondo State, Nigeria. E-mail: [email protected]

ABSTRACT

The efficacy of three botanicals, Cymbopogon citrates, Hyptis suaveolens and Eucalyptus globulus were tested on Callosobruchus maculatus (F), a pest of cowpea under ambient laboratory conditions. Oil extracts were obtained using soxhlet apparatus and petroleum ether as solvent. Efficacies of the extracted oils were determined on counted Callosobruchus maculatus and cowpea seeds in petri dishes. Insect mortality was observed at the different concentration levels for a few minutes and repeated three times for three weeks. In a screen house experiment, 1.0% concentration was observed to be the average and most effective concentration and subsequently selected as a basis for comparison in all the selected botanicals. The application of Hyptis suaveolens at 1.0 % was observed to be the most effective and significantly different from other botanicals while Eucalyptus globulus was the least effective. Keywords: Pest control, Hyptis, Eucalyptus, Callosobruchus maculatus, Cymbopogon INTRODUCTION Henneberry, 1990). This research work was based on the laboratory evaluation of use of three botanical Cowpea, (Vigna unguiculata) (L). Walp is the one of oils in the control of insect pest of cowpea. the most ancient crops known to man. It is an annual legume and is commonly referred to as Southern MATERIALS AND METHODS pea, black eye pea, etc. The largest production is in This experiment was carried out at the Department of Africa, with Nigeria and Niger predominating. The Plant Science and Biotechnology, Adekunle Ajasin cowpea is predominantly a hot weather crop. It is University, Akungba-Akoko. The insect pest, more tolerant to drought, water logging, infertile soils, Callosobruchus maculatus used was obtained from a and acid stress than common bean. Cowpea can be culture of infected cowpea seeds maintained at grown successfully under conditions that are totally ambient condition in the Department of Plant Science unsuitable for the common bean. They are much less and Biotechnology Laboratory. Fresh plant leaves of tolerant to cold soils than common bean. Cowpea is Hyptis suaveolens, Eucalyptus globulus and considered nutritious with a protein content of about Cymbopogon citratus were collected at maturity from 24.8%, fat content of 1.9%, fibre content of 6.3%, different locations at Akungba Akoko,Ondo State, carbohydrate content of 63.6% & water content of 8- Nigeria during the rainy season. The leaves were 9%. detached from the stalk, washed and sun-dried for The cowpea bruchid, Callosobruchus maculatus (F.) about 3 weeks before being pulverized using an (Chrysomelidae: Bruchin), is a worldwide pest of electric blender. stored cowpea grain (Vigna unguiculata (L.) Walp. The soxhlet apparatus (extractor) was used for the Several methods had been adopted in its control. extraction of oils of Eucalyptus globulus, Hyptis Some were effective while there were draw backs suaveolens and Cymbopogon citratus and the observed in some, especially in the use of synthetic different oils stored in McCartney bottle which were chemicals. kept in a refrigerator at 5°C before use. Research in recent years has been turning more 10ml of oil of Hyptis suaveolens, Eucalyptus globulus towards selective bio-rational pesticides, generally and Cymbopogon citratus was prepared separately perceived to be safer than the synthetics (Anarson et for the experiment while 40 seeds of Cowpea (Vigna al, 1989) and extensive works on the use of plant unguiculata) were put in each Petri-dish, with three extracts in pest control have also been documented. replicate and one control. The control was a petri dish Consequently, plant derived oils and powders have of cowpea seeds without treatment application. recently been evaluated and shown to be effective Twenty (20) pairs consisting of 20 males and 20 against a number of insect pests (Butler and females of C. maculatus were put in each Petri-dish Agric. Biol. J. N. Am., 2013, 4(4): 419-421

and the botanical oils were applied at each setup. control of Okra field insect pests, Podagrica uniforma This experiment was monitored for 3 weeks. At the and P. sjostedti. end of the experiment, data collection was based on Essential oils are used in perfumery, aromatherapy, mortality rate at each concentration levels and data cosmetics, incense, medicine, household cleaning was subjected to analysis of variance and means products and for flavouring food and drink. They are compared using Tukey’s Honestly Significant Test at responsible for the aroma and flavour associated with 5% level of probability. herbs, spices and perfumes. They are also called volatile oils because they easily diffuse into the air RESULTS AND DISCUSSION where they are then detectable by our olfactory Tables 1 to 3 show the cumulative mortality rate of senses. Essential oils are usually terpenoids another insect pests with the application of the three large class of secondary chemicals. Their presence botanicals for three weeks. in certain plant parts probably reflects their functions. It has also been reported that some organic pest In tables 1to 3 it could be observed that the three control product such as Orange Guard use a citrus botanicals are significantly different, P > 0.05, fruit peel base, such as from lemons and oranges. compared to one another, which makes Hyptis Citrus oils kill many flying and crawling insects on suaveolens the most effective. The least performance contact by destroying the waxy coating of the insect’s observed in Eucalyptus globulus was not an respiratory system. Other organic pesticides use indication of weak potentials as it has equally been natural extracts to repel rather than kill pests. Some reported in some research works as being effective. products use garlic or hot peppers and essential oils Consequently, this variance in potentials may likely of herbs such as cloves to repel insects and other be dependent on the concentration levels adopted in pest. the research. Observations made in this experiment In addition to terpenoids, phenolic compounds are corroborate the view of several researchers on the responsible for the aroma and flavour of some adoption and use of plant oils in pest control. spices. For example eugenol is a phenolic compound Consequently, the high infestation of cowpea at found in both cinnamon (Cinnamonum spp) and almost every stage of its growth and concomitant cloves from Syzygium aromaticum. The functions of damage necessitate a proactive and promising essential oils were once considered waste products. approach to its control. Although the use of synthetics However, the biosynthetic pathways that yield had been adopted but since its use was faced with essential oils are specialized and imply an several challenges, the use of botanicals had been expenditure of energy by the plant of their production. gaining attention in recent times. The use of essential Another debated role for essential oils is to inhibit oils had equally been adopted and proven effective. competing plants or allelopathy. For example, Raja et al., (2001) reported that pulse stored in gunny essential oils in sheds leaves can leach into the soil bags and treated with aqueous extracts from leaves where they may inhibits the germination or growth of of Melia azadirachta, Hyptis suaveolens and tuber of other plants competing for the same resources (e.g. Cyperus rotundus, were effectively protected without light, minerals nutrient, water). As with many other any infestation for up to 6 months. Kim et al, 2003 secondary compounds, they are now believed to also reported the insecticidal activities of aromatic plant defer herbivory and prevent infections by pathogens extracts and essential oils against Sitophilus oryzae i.e. bacteria and fungi. Nature had provided plant and Callosobruchus chineensis. extracts that make very effective pesticides and Also, Keita et al, (2001) reported that seeds treated insect repellants, which seems to be cheaper, safer with botanical extract oils did not lose their viability and more easily produced than the synthetic and they also established that powder made from insecticides. essential oil of different basils provided complete On this basis, the use of botanical oil extracts protection against C. maculatus and did not show any should be seen as an effective protective measure in significant effect on the seed germination rate. In a pest control and adoption of use extended to other similar experiment on pest control focused on the crops of economic value. adoptive use of extract, Tapondjou et al., (2002) showed that the dry ground leaf of Chenopodium ambrosioides inhibited F1 progeny production and adult emergence of the Callosobruchus chinensis and C. maculatus, while Olotuah (2010) reported that the use of Cashew Nut shell liquid is effective in the

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Table1: Cumulative mortality rate of insect pests determined REFERENCES at different times at the first week of the experiment

2 MINUTES 4 MINUTES 6 MINUTES Arnason, J.T., B.J.R. Philogen and P. Morand. 1989. Hyptis 40.0±0.0a 0±0.0c (0%) 0±0.0b (0%) Insecticides of Plant Origin. ACS, Symposium Series suaveolens (100%) No. 387, American Chemical Society, Washington, Cymbopogon 37.5±0.5b 2.5±0.5b 0±0.0b (0%) D.C. USA, pp: 213. citratus (93.75%) (6.25 %) Eucalyptus 27.0±1.0c 7.5±1.5a 5.5±0.5a Butler, G.D., Jr and Henneberry, T.J. 1990. Pest Control on globulus (67.5%) (18.75%) (13.75%) Vegetables and Cotton with Household Cooking Oils Control 0±0.0d (0%) 0±0.0c (0%) 0±0.0b (0%) Means in each column bearing the same letter are not significantly different at the 5 % level and Liquid Detergents. Southwest. Entomol. 15, 123- of probability using Tukey’s Test 131.

Table2: Cumulative mortality rate of insect pests Keita, S.M., C.Vincent, J.Schmit, P, Arnason and J. T. determined at different times at the second week of the Belange,2001. Efficacy of Essential oil and Ocimum experiment basilicum L. And O. gratissimum L. applied as an insecticidal fumigant and powder to control 2 MINUTES 4 MINUTES 6 MINUTES Callosobruchus maculatus (Fab.) (Coleoptera: Hyptis 40.0±0.0a 0±0.0c (0%) 0±0.0b (0%) Bruchidae). Journal of Stored Products Research.37 suaveolens (100%) (4):339-349. Cymbopogon 35.5±0.5b 4.5±0.5b 0±0.0b (0%) citratus (88.75%) (11.25%) Kim, S.I., J.Y. Roh, D.H. Kim, H.S. Lee and Y.J Ahn, 2003. Eucalyptus 26.0±0.5c 8.5±0.5a 5.5±0.5a Insecticidal activities of Aromatic plant extracts and globulus (65%) (21.25%) (13.75%) essential oils against Sitophilus oryzae and Control 0.0±0.0d 0.0±0.0c 0.0±0.0b Callosobruchus chineensis. Journal of Stored products (0%) (0%) (0%) Means in each column bearing the same letter are not significantly different at the 5 % level Research 39(3): 293-303. of probability using Tukey’s Test Olotuah, O.F. and Ofuya, T.I. (2010)a: Comparative

Protection of Cowpea, Vigna unguiculata, (L.) Walpers Table3: Cumulative mortality rate of insect pests against Field Insect Pests using Cashew Nut Shell determined at different times at the third week of the Liquid and Cypermethrin (Cymbush). P. J. Nut.9 (2): experiment 158-161. 2 MINUTES 4 6 MINUTES MINUTES Raja, N., A. Babu, S. Dorn and S. Ignacimuthu, 2001. Hyptis 40.0±0.0a 0±0.0c 0±0.0b Potential of Plants for protecting Stored pulses from suaveolens (100%) (0%) (0%) Callosobruchus maculatus (Coleoptera: Bruchidae) Cymbopogon 38.0±0.5b 2.0±0.0b 0±0.0b infestation. ESN Occasional Publication,31: 227-235. citratus (95%) (5%) (0%) Taponjou, L.A., C. Adler, H.Bouda and D.A Fontan,2002. Eucalyptus 28.0±0.5c 8.0±0.5a 4.0±0.5a Efficacy of Powder and Essential Oil from globulus (70%) (20%) (10%) Chenopodium ambrostodes leaves as post-harvest Control 0±0.0d (0%) 0±0.0c 0±0.0b grain Protestants against six-stored product beetles, (0%) (0%) Journal of Stored Product Research. 38(4) 395-402. Means in each column bearing the same letter are not significantly different at the 5 % level of probability using Tukey’s Test

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