Insecticidal Activity of Latex of Euphorbia Antiquorum on Agricultural Insect Pests
Date
2001-11-16
Authors
De Silva, W. A. P. P.
Manuweera, G. K.
Karunaratne, S. H. P. P.
Journal Title
Journal ISSN
Volume Title
Publisher
University of Peradeniya, Peradeniya, Sri Lanka
Abstract
Euphorbia antiquorum (Euphorbiacea) (Sinhalese name: Daluke), a plant native to Sri lanka, has various medicinal uses. Its latex has been described as having emetic, purgative, diuretic and poisonous properties. The latex is used to control paddy pests such as Scirpophaga insertulas and Sitophelus orizae in rural areas of Sri Lanka. This study was undertaken to investigate the potential use of E. antiquorum latex as an insect pest control agent and to isolate the compounds that are responsible for insect control.
Latex of E. antiquorum was collected from Ebbagala (Kurunegala District) and dissolved separately in 7 solvents dichloromethane, distilled water, n-hexane, petroleum ether, methanol, diethyl ether and acetone. Activity of each solution was tested against laboratory colonies of the aphids Myzus persicae and Aphis gossipii, using a potters 'sprayer. Both species showed 100% mortality at levels of 10,000ppm of the xylene solution. At this concentration the degree of activity was much lower in acetone (20% mortality), distilled water (8% mortality) and methanol (38% mortality) solutions. The latex when dissolved in dichloromethane, n-hexane and diethyl ether formed a white precipitation when applied on insects. Insecticidal activity of the xylene solution (10,000ppm)was further tested on paddy bug Leptocoriza oratorius (48% mortality) black bug Scotinophara lurida (0% mortality) brown plant hopper Nilaparvata lugens (50% mortality) and cabbage looper Chrysodeixis erisoma. Predatory ladybird beetles, Harmonia octomaculata and Menochilus sexmaculates showed 0% mortality whereas predatory the spider Lycosa pseudoannulata showed 100% mortality at this concentration. control experiments were done using seven solvents dichloromethane, distilled water, n-hexane, petroleum ether, methanol, diethyl ether and acetone.
Of the seven latex solutions, latex in xylene gave clear spots on thin layer chromatography (TLC). Column chromatography (florisil 60-80 mesh size) was used for the separation of xylene solution. Sample was eluted with n-hexane (120ml) and 5ml fractions were collected. Bioassays were carried out using Myzus persicae with each fraction (0.25microliter) of each solution was topically applied on to the thorax of the insect using a microapplicator). Fraction 17 had the highest bioefficacy (80%mortality). Separated fractions were studied by TLC and high performance liquid chromatography (HPLC). Fraction 17 showed one clear spot on TLC and showed three separated peaks on HPLC. LD50 values for the xylene latex solution (10,000ppm) and the 17th fraction were 0.06721ppm and 3.221ppm respectively when tested on Myzus persicae.
Description
Keywords
Science , Insecticidal , Agricultural , Euphorbia , Antiquorum
Citation
Proceedings & abstracts of the Annual Research Sessions 2001,University of Peradeniya, Peradeniya, Sri Lanka,pp.116