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During the past six decades chemical preparations have plays an important role and dominated in pest control. This has led to pollution of environment, danger to humans and developing resistance against toxicants of over 500 species of insects and mites (Thomas, 1999), forcing scientists to develop new kinds of insecticides. Plant products and microbials have been the subject of thorough investigation for the past few years and have emerged as an excellent alternative to synthetic insecticides for the management of insect pests. The compounds from plants having insecticidal property shows a number of useful activities like toxicity, repellence against feeding and oviposition, deterrence and insect growth regulator activity etc. (Mordue, 2004).
Cruciferae pests are one of the most limiting factors in cabbage production. The monitoring of cabbage fields at ICAR, Umiam, Meghalaya in 2010 showed high densities of large white butterfly, Pieris brassicae (L.) populations. The cabbage white butterfly, Pieris brassicae (Linnaeus) (Lepidoptera: Pieridae) is a serious pest of cabbage (Bhalla and Pawar, 1977) and the insect pest alone causes more than 40% of yield loss of vegetables annually (Ali and Rizvi, 2007). It causes extensive damage in almost all parts of India including north eastern states, during seedling, vegetative and flowering stages of cole crops (Lal and Ram, 2004; Younas et al., 2004).
Bio-insecticides are distinguished for their favorable eco-toxicological traits and low initial toxicity. The efficacy of bio-pesticides depends considerably on application timing and the aim of this investigation was to assess the bio-efficacy of eco-friendly insecticides against Pieris brassicae.
1 Materials and Methods
Field experiments were conducted during 2009-2010 in Entomology Division of ICAR Research Complex for NEH Region at Umiam, Ri-Bhoi, Meghalaya (Table 1). The cabbage variety; 'Wonder Ball' was transplanted on November, 2009 on the plot size of 3 x 2.5 m² and a plant to plant distance of 45 cm x 45 cm. Thirty plots having Pieris brassicae infestation were selected and five cabbages/plot were tagged. The treatments consisted of Annonin, Azadirachtin (oil base 300 ppm), Neem Seed Kernel Extract 300 ppm, Garlic Extract (1%), Karanjin, Bacillus thuringiensis (Bt), Beauveria bassiana, Spinosad 45 SC and Endosulfan 35 EC. The experiment was carried out in Randomized Block Design (RBD) and each treatment was replicated three times. The treatments were applied...