Insecticidal Activity of Crude Ethanolic Extracts of Five Philippine Plants Against Cabbage Worm, Crocidolomia Pavonana Fabricius (Lepidoptera: Crambidae)
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Philippine Journal of Science 147 (3): 513-521, September 2018 ISSN 0031 - 7683 Date Received: 20 Feb 2018 Insecticidal Activity of Crude Ethanolic Extracts of Five Philippine Plants against Cabbage Worm, Crocidolomia pavonana Fabricius (Lepidoptera: Crambidae) Abigaile Mia V. Javier1,*, Virginia R. Ocampo2, Flor A. Ceballo2, and Pio A. Javier2 1Agriculture Research Section, Atomic Research Division, Philippine Nuclear Research Institute- Department of Science and Technology, Commonwealth Avenue, Diliman, Quezon City 1101 Philippines 2Institute of Weed Science, Entomology and Plant Pathology, College of Agriculture and Food Science, University of the Philippines Los Baños, College, Laguna 4031 Philippines Plant substances play a major role in insect pest management by exhibiting their insecticidal activity through toxicity, antifeedant activity, repellency, and growth regulatory activity. Ethanolic extracts from five plant species – “lantana”, Lantana camara (Linnaeus); oregano, Coleus amboinicus (Loureiro); “langkauas”, Alpinia pyramidata (Blume); “luyang dilaw”, Curcuma longa (Linnaeus); and “chichirica”, Catharanthus roseus (Linn.) – were evaluated for their insecticidal activities including contact and residual toxicity, antifeedant activity, and growth regulator activity against third larval instar of cabbage worm, Crocidolomia pavonana (Lepidoptera). Among the five ethanolic extracts, Cu. longa was the most toxic to cabbage worm when applied topically (LD50=51.00 µg/g) and through leaf residue film method (LC50=116.73 µg/mL) at 72 h after treatment. L. camara ranked second in providing contact toxicity and leaf residue film method. Ethanolic extract from Co. amboinicus showed high antifeedant activity against cabbage worm at 500 µg/mL. All the ethanolic extracts showed insect growth regulatory activities expressed in high larval and pupal mortalities for Co. amboinicus and Cu. longa; high number of abnormal adults for Ca. roseus; and shortened lifespan of adults in L. camara and A. pyramidata. In view of the overall pesticidal properties of the plants, ethanolic extracts from Cu. longa and L. camara can be exploited as botanical insecticides for cabbage worm management. Key words: antifeedant, botanical insecticide, Curcuma longa, Lantana camara, topical toxicity INTRODUCTION 2003). It is considered as one of the major constraints in Brassica production because the larvae feed on young Cabbage worm, Crocidolomia pavonana Fabricius leaves and attack the cabbage head that could lead to 100% (Lepidoptera: Crambidae), is one of the major pest of yield loss (Morallo-Rejesus & Navasero-Ward 2003). crucifers. Newly hatched larvae feed on the underside of the leaf and disperse throughout the other plant parts as The usual control employed against lepidopterous moths they mature. In some cases, they reach the center of the like cabbage worm is the use of synthetic pesticides. plant and produce mass webbing and frass (Smyth et al. However, continuous and improper use of chemical insecticides has several drawbacks; these include *Corresponding author: [email protected] insecticide resistance, toxicity to natural enemies, risk to 513 Philippine Journal of Science Javier et al.: Ethanolic Extracts Against Cabbage Worm Vol. 147 No. 3, September 2018 human health, and lower prices because of consumers' shift Plant Materials and Preparation of Ethanolic to buying organic products (Bommarco et al. 2011). The use Extracts of botanical pesticides is an effective alternative approach Fresh leaves of L. camara (Verbenaceae), Co. amboinicus for controlling many insect pests. Many plants have been (Lamiaceae), and Cymbopogon nardus Linn. (Poacaeae); reported to be toxic against cabbage worm. Methanolic rhizomes of A. pyramidata (Zingiberaceae) and Cu. longa extracts from seeds of Barringtonia asiatica, Melia (Zingiberaceae); and leaves, stems, and flowers of Ca. azedarach, and Annona muricata showed potential control roseus (Apocynaceae) were collected during Jun-Sep against C. pavonana. Mixture of these three plants at 0.1% 2012 in areas of Los Baños, Laguna. Plants collected caused 100% mortality at 3 days after application using were brought to the laboratory, washed with dechlorinated leaf disc method against second instar larvae (Retnasari et water, and air-dried under room temperature of 28±1 ºC. al. 2017). Mixture of ethyl acetate extract from leaves of The extraction procedure was conducted at the Insect Tephrosia vogelii, seeds of Brucea javanica and fruit from Physiology Laboratory of IWEP. The rhizomes were Piper aduncum (1:3:2.5) showed remarkable insecticidal chopped into small pieces, while the other plant parts activity against second instar larvae of C. pavonana with were detangled and cut into smaller pieces using scissors. LC50 value of 0.03% (Lina et al. 2013). In Indonesia, two The plant parts were oven-dried at 60 ºC for 48-72 h. The botanical insecticide formulations – mixtures (at 0.1%) air-dried plant parts were ground using the Nutri Tech of Piper retrofractum and An. squamosa, and mixtures of blender-juicer set at 32000 rpm. Two hundred grams (200 Aglaia ordorata and An. squamosa – were more effective g) of dried samples were kept in a clean bottle, soaked than the synthetic insecticide (deltamethrin) in reducing the in 500 mL of 95% ethanol for at least two weeks for population of C. pavonana in the field (Dadang et al. 2011). homogenization. After homogenization, the liquid mixture was filtered in Whatman filter paper No. 1 and the filtrate Although botanical extracts have been studied in many was concentrated using a rotary evaporator until all the laboratory tests, very few studies are available on study solvent had evaporated. The resulting ethanolic extracts of insecticidal activities of ethanolic extracts against were stored at 4 °C in airtight bottles until use in bioassay. cabbage worm. Therefore, in this study, the researchers reported the insecticidal activity of ethanolic extracts of five Philippine medicinal plants including Alpinia pyramidata, Preparation of Test Solutions Lantana camara, Coleus amboinicus, Curcuma longa, and Stock solutions and lower concentrations were prepared Catharanthus roseus against cabbage worm. Most of them for each ethanolic extracts using acetone as diluent. The were reported toxic against stored pests and mosquitoes. final doses and concentrations for each plant extract were These plants also showed promising insecticidal activity prepared from the stock solution using acetone as diluent. using aqueous, alcoholic extracts using coconut wine Final doses and concentrations against cabbage worm (Javier et al. 2015), and essential oil extracts against Plutella were determined from preliminary bioassays. Series of xylostella Linnaeus (Javier et al. 2016) and Spodoptera dilutions between doses and concentrations that caused litura Fabr. (Javier et al. 2017). To evaluate the insecticidal 10-90% mortality of test insect was identified from the activity of ethanolic extracts of five Philippine medicinal preliminary results. plants (A. pyramidata, L. camara, Co. amboinicus, Cu. longa, and Ca. roseus), the researchers determined the Bioassay Procedures contact toxicity, residual toxicity, antifeedant property, and Contact Toxicity Test: Topical Application Method. morphogenetic effects against third instar larvae of cabbage One microliter (1 µL) of the solution of each treatment worm. The study was conducted at LB Uichanco Wing, was topically applied equivalent to doses of 8, 15, 31, Institute of Weed Science, Entomology and Plant Pathology 61, 122, and 245 µg/g larva on the thoracic region of (IWEP), College of Agriculture and Food Sciences (CAFS), each larva using a Hamilton Repeating Dispenser plus University of the Philippines, Los Baños (UPLB), College, a 10-µL microsyringe. Acetone and chlorfluazuron Laguna from Jun 2012 to Nov 2013. (Atabron 5 EC) at a dose of 12 µg/g larval body weight (recommended rate) served as the negative and positive controls, respectively. Ten larvae were placed in a Petri dish and were given 8 cm-diameter of pechay leaf as food. MATERIALS AND METHODS Ten larvae were used per replication and each treatment was replicated four times. In all the tests, third instar larvae Rearing of C. pavonana of cabbage worm with an average weight of 4.089 mg per Larvae of cabbage worm were collected from pechay larva were used. Mortality was recorded at 24, 48, and 72 plants, Brassica rapa (Loureiro), grown around the h after treatment (HAT) (Javier et al. 2016; Javier et al. greenhouse of the IWEP, UP Los Baños and were reared in 2017; Javier et al. 2018). the laboratory following the method of Javier et al. (2018). 514 Philippine Journal of Science Javier et al.: Ethanolic Extracts Against Cabbage Worm Vol. 147 No. 3, September 2018 Residual Toxicity Test: Leaf Residue Film Method. An the LD25 of the ethanolic extracts based on contact toxicity 8 cm-diameter pechay leaf was cut and 0.50 mL of the test of the five extracts using topical application at 72 HAT. different test solutions (31.25, 62.5, 125, 250, 500, and Third instar cabbage worm larvae were topically treated 1000 µg/mL) was evenly spread on both abaxial and with 30.57 μg/g body weight of the ethanolic extracts. adaxial sides of the leaves using forceps. After air-drying for about 10 min, each treated leaf was placed in a Petri Each of the treated larvae was released inside a Petri dish dish measuring 9 cm, and ten third instar larvae of cabbage containing moistened filter paper and pechay