Abstract—Viscum album berry lectin (MChbL) was tested against rustic shoulder-knot (Apamea sordens) and turnip moth (Agrotis segetum) larvae. MChbL affected larval development and survival at different growth stages. MChbL produced ca. 40% mortality of larvae when incorporated into an artificial diet at a level of 0.01% (w/w). MChbL affected larval gut proteolytic enzymes decreasing the total midgut protease activity. N-terminal amino acid sequencing of MChbL showed homology to osmotin-like protein from Hevea brasilienisis and -amylase/trypsin inhibitor from Zea mays with 60% homology. The results show that MChbL may be useful in the development of insect resistance in important agricultural crops. Keywords— Insecticidal activity, lepidoptera, mistletoe, Viscum album. I. INTRODUCTION ECTINS are among wide range of natural defense proteins found in plants [1]. They are heterogeneous group of proteins classified together on the basis of their ability to bind in a reversible way to well-defined simple sugars or complex carbohydrates. The main characteristic of these proteins is their ability to interact specifically with carbohydrates and to combine with glyco-components of the cell surface. While the physiological functions of plant lectins have not yet been fully elucidated, one possible function that of serving as a chemical defense towards large array of insect pests belong to the Coleoptera, Homoptera, Diptera and Lepidoptera order has been well documented [2]-[5]. Insecticidal activities of plant agglutinins are associated mostly with two main groups of plant lectins: monocot mannose-binding and chitin-binding lectin groups. GNA and wheat germ agglutinin are the best characterized representatives of these groups which are increasingly used in development of transgenic crops [6]. European mistletoe (Viscum album L.) is considered to be a toxic plant, and its content of toxic lectins lends support to this. Poison centers report toxicity of the whole plant, but especially the berries [7]. Due to the environmental concerns Mariam Gaidamashvili is with the Laboratory of Plant Physiology, Department of Biology, Iv.Javakhishvili Tbilisi State University, 0128, Tbilisi, Georgia (corresponding author’s phone: +995 32 2304148). Eka Khurtsidze is with the Laboratory of Plant Physiology, Department of Biology, Iv.Javakhishvili Tbilisi State University, 0128, Tbilisi, Georgia (phone: +995 32 2304148). of pesticide use and limited list of effective alternatives mistletoe lectins would be promising candidates for biological pesticides that have low mammalian and environmental toxicity. In the present paper we characterized Viscum album agglutinin (MChbL) and showed its antinutritive effect towards serious herbivore Lepidoptera pests of agricultural importance Apamea sordens Hufn. and Agrotis segetum Schiff. (Lepidoptera: Noctuidae). We found chitin-binding mistletoe lectin has high homology to thaumatin protein family and demonstrated its detrimental effect on larval development at different growth stages. The possible implication of mistletoe agglutinin as biological pesticide against Lepidoptera pests is proposed. II. MATERIALS AND METHODS A. Materials The fruits of European Mistletoe were harvested in mountainous region of East-Georgia, in winter (December- February) and stored at -15°C until use. B. MChbL Purification Mistletoe chitin-binding lectin (MChbL) was prepared as described with some modifications [8]. The plant material was homogenized in medium consisting of 0.05 M Na-acetate buffer, pH 4.5, at ratio 1:3 (g/ml). The extracts were centrifuged at 5,000g for 15 min; supernatant was filtered through Miracloth (Calbiochem., USA) and Watman GF/c filter. The soluble protein fractions were purified by affinity chromatography on the agarose (Serva) and chitin (Sigma) sorbents, dialyzed, lyophilized and stored until use. C. Insect Feeding Trials The larvae of A. sordens and A. segetum were obtained from Khashuri region (East Georgia). Larval cultures were reared continuously at 25±1°C and relative humidity of 65- 75%, under a L16/D8 light regime. To examine the effects of MChbL on insect larvae, they were maintained in plastic boxes, with perforated plastic covers and reared on a control and experimental diet with or without lectin, respectively. The lectins were incorporated into natural diet daily at a level of 0,001% (w/w). 10-15 larvae were used per treatment. Insect survival was estimated daily, the weights of larvae and pupae were measured and the duration of developmental Larvicidal Activity of Mistletoe Lectin on Lepidopteran Pests: Mechanisms of Action Mariam Gaidamashvili, and Eka Khurtsidze L International Conference on Civil, Biological and Environmental Engineering (CBEE-2014) May 27-28, 2014 Istanbul (Turkey) http://dx.doi.org/10.15242/IICBE.C514525 45