FACTORS INFLUENCING LARVICIDAL ACTIVITY OF BACILLUS THURINGIENSIS AGAINST FILARIAL VECTOR CULEX QUINQUEFASCIATUSSUCHARITA GHOSH1, ARNAB CHATTERJEE, SYED AFRIN AZMI1, RAKTIMA BANDYOPADHYAY, SURAJIT DAS, NIMAI CHANDRA SAHA AND SOUMENDRANATH CHATTERJEEAbstract The present study was carried out to investigate the larvicidal activity of native Bacillus thuringiensis (Bt) strain under different physico-environmental condition. Three factors were considered i.e., temperature, availability of larval foods and natural gut microbes of larva. The activity of Bt on Culex larvae was checked at 4 different temperatures (25 oC, 30 oC, 35 oC and 40 oC) and under different conditions, i.e. in normal pond water, in tap water, by supplying natural foods (phytoplankton, zooplanktons) and artificial food (dog biscuit, fish food). Bt exerted itâs activity at a particular temperature range and showed optimum activity at 35 oC. It was found that presence of available food decreases the efficacy of Bt. When the larvae were exposed to the antibiotics doxycycline and tetracycline the larval mortality significantly increased within a short period of time and it was found that without normal gut microbiota, larvae can't survive.
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