Evaluation of Some Plant Origin Commercial Biopesticides against Red Spider Mite, <i>Oligonychus coffeae</i> Nietner (Acarina: Tetranychydae) in Tea

Abstract

An experiment was conducted to evaluate some plant origin commercial biopesticides against red spider mite in tea under both in the Entomology Laboratory and main farm of Bangladesh Tea Research Institute (BTRI), Srimangal, Moulvibazar during the period from March 2013 to December 2014. Bio-Cawach ( Pongamia pinnata ), Karanza ( Azadirachta indica + Pongamia pinnata ), Miticon (Various herbs, alkaloids and salt of fatty acids), Neemakar (Neem, Karanja & Tulsi), Rescue ( Vitex negundu + Clerodendron infortunatum ) and Torpedo ( Sophora alopecuroides + Stemona sessilifolia ) were considered as treatments and dosages were @ 0.8 ml, 1.0 ml, 1.0 ml, 1.0 ml, 0.5 ml and 0.5 ml, respectively. Data were collected at 24 HAT, 48HAT, 72HAT (Hours after Treatment) in the laboratory and at weekly interval in field condition. Results indicated that all the biopesticides showed the toxic effect on red spider mite in tea and significantly reduced mite population both in laboratory and field conditions. In laboratory condition, Miticon showed the highest (93.28%) toxic effect at 72HAT followed by Karanza (92.55%) against red spider mite where as Bio-Cawach, Neemakar, Rescue and Torpedo exhibited pronounced acaricidal action (89.78%~91.67%) at 72HAT. Similar trend of toxicity was found at 24HAT & 48HAT. The mortality was in a linear trend i.e. increasing with increasing of time. From the field evaluation, it was found that the highest (81.34%) reduction in mite population was observed in Miticon treated plot followed by Rescue treated plot (81.01%). The lowest (74.07%) reduction in mite population was observed in Bio-Cawach treated plot. The order of toxicity of the six plant origin commercial biopesticides on adult red spider mite in both laboratory and field condition was: Miticon>Rescue>Neemakar>Karanza>Torpedo>Bio-Cawach. Application of the tested biopesticides did not affect the natural predators such as Stethorus gilvifrons and Oxyopes sp. Tea samples made from biopesticide-treated shoots were found taint free when subjected to organoleptic evaluation. These eco-friendly low cost plant products can therefore be incorporated in the strategy of integrated pest management (IPM) to reduce the load of chemical pesticides in tea.