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ABSTRACT
The ethanol extract of Polygonum aviculare L. was investigated for its insecticidal activity against the peach aphid (Myzus persicae), the cabbage aphid (Brevicoryne brassicae L.), Plutella xylostella L. (Lepidoptera: Plutellidae), Spodoptera exigua and the Northern armyworm Mythimna separate (Walker) (Lepidoptera: Noctuidae). Results showed that the ethanol extract of P. aviculare had a potent toxicity on M. persicae and P. xylostella, moderate activity on M. separate., B. brassicae and S. exigua, where mortality percentages were 95.72, 76.67, 43.82, 34.14 and 33.53%, respectively, after 48h. The extract activity on M. persicae and P. xylostella were concentration-dependent. The LC^sub 50^ of M. persicae and P. xylostella were 2.81 and 9.44 mg/ml, respectively. The sub-fractions, with varying polar-solvents, were also tested for their activity against P. xylostella and the results showed that petroleum ether extract exhibited the strongest activity with the mortality of 97.95 %, followed by the chloroform extract 70.14%, ethyl acetate extract 11.53% and water-soluble part 0%. The results of the present work indicated a potential activity of P. aviculare as insecticide for the management of M. persicae and P. xylostella.
Key words: Polygonum aviculare L; Agricultural Pests; Insecticidal Activity.
INTRODUCTION
The search for new strategies or natural products to control destructive insects is desirable due to prevalent occurrence of pest resistance and negative impact on natural enemies as well as environmental and health harm (Rattan, 2010 and Regnault-Roger et.al., 2012). Utilization of plants' bioactive molecules is one of for these alternatives. Plants are the most efficient producers of phytochemicals in the environment, including secondary metabolites that are used by the plant in defense against phytophagous insects (Boulogne et al., 2012). Over 2000 species of plants are known to possess some insecticidal properties (Klocke, 1989) and many works have reported the bioactivity of extracts from various plants against important agricultural insect pests (Park et al., 2002; González-Coloma et al., 2011; Guo et al., 2014; Moussa et al., 2014 and Amer et al., 2014).
Polygonum aviculare is an annual herbaceous plant, belongs to family Polygonaceae. It can be found in many parts of the world (Granica et al., 2013). In China, it is mainly distributed in southwest regions and has been commonly used in traditional oriental medicine because of its pharmacological properties (Hsu, 2006 and Park...