Pol. J. Environ. Stud. Vol. 26, No. 4 (2017), 1653-1662 DOI: 10.15244/pjoes/73800 Original Research Chemical Composition and Insecticidal Activities of Essential Oils of Myrtaceae against Tribolium castaneum (Coleoptera: Tenebrionidae) Saima Siddique1*, Zahida Parveen3, Firdaus-e-Bareen2, Abida Butt4, Muhammad Nawaz Chaudhary1, Muhammad Akram5 1College of Earth and Environmental Sciences, University of the Punjab, 54890-Lahore, Pakistan 2Department of Botany, University of Punjab, Lahore-54890, Pakistan 3Applied Chemistry Research Centre, PCSIR Laboratories Complex, Lahore-54600, Pakistan 4Department of Zoology, University of the Punjab, 54890-Lahore, Pakistan 5Medicinal Botanic Centre, PCSIR Laboratories Complex, Peshawar-25000, Pakistan Received: 22 April 2017 Accepted: 15 May 2017 Abstract The present study was designed to determine chemical composition of essential oils extracted from different species of the Myrtaceae family and to evaluate their insecticidal activities against Tribolium castaneum (Coleoptera: Tenebrionidae). The essential oils of 10 species were extracted by hydrodistillation and analyzed by a gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The main component of Eucalyptus crebra, E. microtheca, E. rudis and Melaleuca quinquenervia essential oils was 1,8-cineole (31.6-49.7%). E. melanophloia and E. tereticornis contained p-cymene (41.8-58.1%) as a major component, while Eucalyptus kitsoniana and E. pruinosa essential oils were dominated by α-pinene (25.8-31.4%). Eugenol methyl ether was identified as a major component in M. bracteata essential oil (82.3%). α-Pinene (31.4%) was the main component in the C. viminalis essential oil. Essential oils of all selected plant species showed good insecticidal activities against T. castaneum when compared with pyrethroid as a positive control. Eucalyptus rudis proved most potent against T. castaneum, followed by M. bracteata, M. quinquenervia, and C. viminalis. The results of this study indicate that essential oil of Myrtaceae leaves have potential to be used in the control of T. castaneum. Keywords: 1,8-cineole, E. melanophloia, hydro-distillation, GC-MS, LC50, M. quinquenervia, α-pinene *e-mail: [email protected] 1654 Siddique S., et al. Introduction most chemical treatments are unsatisfactory and can be dangerous to health. Pakistan is rich in medicinally and Wheat (Triticum aestivum L.) is the major source of economically rich flora. Myrtaceae is represented by protein in human foods and the second main food crop seven genera and 26 species in Pakistan [27]. Keeping in terms of production [1]. More than 2,000 species of in view the insecticidal properties of Myrtaceae and pestiferous insects annually destroy approximately one the need for natural fumigants, the present study was third of the world wheat production, valued at more than designed to explore chemical composition of oil extracted $100 billion [2]. Synthetic chemical insecticides and from 10 species (C. viminalis, E. crebra, E. kitsoniana, fumigants are commonly used to manage pestiferous E. melanophloia, E. microtheca, E. pruinosa, E. rudis, insects throughout the world. Fumigants are preferred E. tereticornis, M. bracteata, and M. quinquenervia) as they are convenient to use, economical, and have from Pakistan and to assess their insecticidal effects for broad spectrum action and rapid penetration into the their potential use as alternatives to chemical fumigants. commodity [3]. However, the use of synthetic insecticides The selection of species was made on the basis of their and fumigants lead to the problems of residual toxicity abundance and availability. in non-targeted organisms, development of resistance and resurgence in pestiferous insect populations, adverse environmental impacts such as ozone depletion, pollution, Material and Methods etc. [4]. These problems have necessitated the search for alternative ecologically safe insect pest control methods. Chemicals Plant-derived insecticides have gained attention in recent years in the pest management industry because of their low Homologous series of C8-C25 n-alkanes used in this toxicity on mammals, short environmental persistence, study were obtained from Sigma Chemical Co. (St. minimal residual activity, and thus wide public acceptance Louis, MO, USA). Ethanol was purchased from Merck [5]. (Darmstadt, Germany). Among plant-derived insecticides, essential oils are worth mentioning. They are secondary plant metabolites, Plant Material aromatic in nature, and give a distinctive odour or flavour to a plant [6]. Chemically, they are complex mixtures Mature leaves of 10 selected species of Myrtaceae comprised of a large number of constituents in variable were collected from different localities around Pakistan ratios [7]. The effectiveness of essential oils and their (Table 1). Taxonomic authentication was performed components in the control of stored product pests has been by Prof. Dr. A. N. Khalid at the Herbarium, Department well-established [8-11]. of Botany, University of Punjab, Lahore, Pakistan. Plant The Myrtaceae (Myrtales) family, comprising at least specimens were deposited in the same herbarium. 133 genera, is a rich source of essential oils. It is found abundantly in Australia, Southeast Asia, and tropical to Isolation of Oils southern temperate America, while a few are domesticated in Africa [12]. The essential oils from Myrtaceae have From each plant, fresh leaves weighing 2 kg were demonstrated antibacterial, anti-inflammatory, fungicidal, hydrodistilled for 3 hours using a Clevenger-type antioxidant, and antiviral properties [13-15]. Studies have apparatus according to the method recommended in the also reported insecticidal activities of different species of European Pharmacopoeia [28]. Oils were dried over Myrtaceae against T. castaneum [16-18]. α and β-pinene, anhydrous sodium sulfate, filtered, and stored at -4ºC in terpinen-4-ol, 1,8-cineole, and methyl eugenol have been a freezer until analyzed. The essential oil contents (%) reported as major components in Myrtaceae essential were expressed as volume of essential oil vs.weight of oils, which have been known for their toxicities against fresh leaves (v/w). pestiferous insects [19-23]. Pakistan is the 9th largest wheat-producing country, Chemical Analysis of Essential Oils accounting for 3.0% of the world’s wheat production from an area of 3.57% of the world [24]. The warm and moist GC-FID climate of Pakistan is conducive to infestation of stored grains by different pests. Tribolium castaneum (Herbst) GC analysis of the essential oils was carried (Coleoptera: Tenibrionidae) is one of the most abundant out on a Shimadzu GC 2010 equipped with a flame and detrimental insects that affects stored grains [25]. ionization detector (FID) and AOC-20i autosampler using Estimated weight loss during storage is approximately 4% a DB-5 MS (30 m × 0.25 mm id, 0.25 µm film thickness) in Pakistan and accounts for about 1,000 million rupees capillary column. The column oven temperature was in losses contributing more than 24% to gross domestic programmed initially at 40-90ºC at the rate of 2ºC/min product (GDP) each year [26]. Sun-drying, aluminium and then raised to 90-240ºC at the rate of 3ºC/min. The phosphine tablets, insecticides, and elemental mercury final temperature was held constant for 5 min. Injector have been used to control pestiferous insects. Although and detector temperatures were maintained at 240 and some degree of control seems to have been achieved, 280ºC, respectively. Essential oil (0.5 µl) was injected in Chemical Composition and Insecticidal Activities... 1655 Table 1. Detail of collected plants from different sites in Pakistan. Plant Name Harvesting Month Locality of Collection GPS coordinates Voucher Number Qarshi Botanical garden, Longitude 72.85 °E, Callistemon viminalis October 2013 BDSS #4055 Hattar, Abottabad Latitude 33.85°N Pakistan Forest Research Longitude 73.11°E, Eucalyptus crebra March 2013 BDSS #4023 Institute, Faisalabad Latitude 31.28°N Pakistan Forest Research Longitude 73.11°E, Eucalyptus kitsoniana March 2013 BDSS #4024 Institute, Faisalabad Latitude 31.28°N Pakistan Forest Research Longitude 73.11°E, Eucalyptus melanophloia March 2013 BDSS #4025 Institute, Faisalabad Latitude 31.28°N Pakistan Forest Research Longitude 73.11°E, Eucalyptus microtheca March 2013 BDSS #4026 Institute, Faisalabad Latitude 31.28°N Pakistan Forest Research Longitude 73.11°E, Eucalyptus pruinosa March 2013 BDSS #4027 Institute, Faisalabad Latitude 31.28°N Pakistan Forest Research Longitude 73.11°E, Eucalyptus rudis March 2013 BDSS #4028 Institute, Faisalabad Latitude 31.28°N Pakistan Forest Research Longitude 73.11°E, Eucalyptus tereticornis March 2013 BDSS #4029 Institute, Faisalabad Latitude 31.28°N Government College Longitude 74.31°E, Melaleuca bracteata April 2013 University botanical garden, BDSS #4040 Latitude 31.57°N Lahore Pakistan Horticulture Authority Longitude 74.30°E, Melaleuca quinquenervia October 2013 BDSS #4042 botanical garden, Lahore Latitude 31.50°N a split-mode ratio of 1:5. Helium was used as a carrier gas Toxicity as Fumigant at a flow rate of 1 ml/min. Quantification of constituents was done by integration of peak areas without using The activity of essential oils against T. castaneum was correction factors. evaluated using the method of Pires et al., (2006) [31]. Different concentrations of essential oils were selected GC-MS on the basis of preliminary tests. Tested concentrations