54 1 Research Fellow (e mail: sikhadeka@yahoo.com; 2 Principal Scientist (e mail: tanwaripm@rediffmail.com); 3 Research Fellow (raj_sumitha@rediffmail.com); 4 Senior Scientist and Principal Investigator (e mail: n_sabir@rediffmail.com); 5 Director (e mail: bambawale1@rediffmail.com; 6 Principal Scientist and In-charge (e mail: drbsingh2000@yahoo.com), Centre for Protected Cultivation Technology, IARI, New Delhi 110012. Indian Journal of Agricultural Sciences 81 (2): 158–62, February 2011 Relative efficacy of agricultural spray oil and azadirachtin against two-spotted spider mite (Tetranychus urticae) on cucumber (Cucumis sativus) under greenhouse and laboratory conditions SIKHA DEKA 1 , R K TANWAR 2 , R SUMITHA 3 , NAVED SABIR 4 , O M BAMBAWALE 5 and BALRAJ SINGH 6 National Centre for Integrated Pest Management, New Delhi 110 012 Received: 25 August 2010; Revised accepted: 1 December 2010 ABSTRACT Laboratory and greenhouse experiments were conducted on relative efficacy of agricultural spray oil and azadirachtin for the management of two-spotted spider mite (Tetranychus urticae on cucumber (Cucumis sativus L.). The treatments included the spray of agricultural spray oil, azadirachtin and combination of both at 0.1, 0.5, 1 and 2% under laboratory conditions and 0.1 and 0.5% under greenhouse conditions, replicated thrice. The laboratory experiment results indicated highest mortality of the mite after 24, 48 and 72 hr of spray in agricultural spray oil + azadirachtin (at 1 and 2%), followed by 2% agricultural spray oil alone in both the seasons. Greenhouse experiment results also indicated highest mortality of the mite on spraying agricultural spray oil + azadirachtin (0.5%) throughout the period, however, agricultural spray oil (0.5%) resulted in highest mortality only a day after spraying during the first season. Key words: Agricultural spray oil, Azadirachtin, Cucumber, Greenhouse, Mites Two-spotted spider mite (Tetranychus urticae Koch), the most common type of mite affecting crop plants, is a serious pest of cucumber in greenhouses. It is a polyphagous pest and is globally considered an important agricultural pest (Jeppson et al. 1975). It is particularly dominant in intensive, high yielding cropping systems and in green houses (Alzoubi and Cobonoglu, 2008). It affects crops by direct feeding, usually colonizing the lower side of the leaves primarily along the mid-ribs and lateral veins. When many mites are present, silken webs and white flakes of molted skin can be observed on the lower leaf surface. It causes severe damage, expressed as leaf wilting, losses of yield quantity and quality and even plant death. The introduction and spread of covered cultivation, along with newer agricultural practices enabled the spider mites to rise in very large populations. It causes significant economic losses in cucumber, tomato, pepper, and bean grown in greenhouses. Many spider mites have become resistant to most of the commonly used pesticides. The loss of acaricidal efficacy as a result of resistant mite population is the major problem encountered in greenhouses (Alzoubi and Cobonoglu, 2008). They have evolved resistant to more than 80 acaricides to date, and resistance has been reported from more than 60 countries (Database from online). Spider mites impose a great expense on greenhouse growers worldwide in terms of damage and control cost and are, therefore, considered one of the most important pests of greenhouse production (Miresmailli et al. 2006). Considerable research efforts have been devoted to finding alternative strategies for suppression of T. urticae. Integrated Pest Management (IPM) is a holistic approach to the management of pests in green house. Now, IPM programmes using biorational insecticides are in progress in greenhouse production. Biorational insecticides are more acceptable than conventional insecticides because they are assumed to be active against pest populations and relatively innocuous to beneficial organisms. Biorational pesticides such as agricultural spray oils and azadirachtin have been shown to be effective against the most common interiorscape pests (Smith and Krischik, 2000). Azadirachtin is a natural biorational pesticide derived from neem tree. It is growth regulating, antifeedant and repellent compound for phytophagous insects (Menke and Gerhard, 2009). It has been demonstrated that the antifeedant effects of azadirachtin on insects varies depending on the concentration and species of the target insects (Xie et al.