Efficacy of two flowable formulations of Bacillus sphaericus against larvae of mosquitoes

Laboratory evaluation revealed that the Spherimos and Vectolex formulations of Bacillus sphaericus produced 97 and 100% larval mortality respectively in Culex quinquefasciatus at a dose as low as 0.008 ml/sq m as against 93 and 97% mortality respectively at 1 ml/sq m in Anopheles stephensi. However, in An. culicifacies similar level of mortality was not observed even at 10 ml/sq m of these formulations. Field evaluation revealed 100% reduction of Cx. quinquefasciatus larvae for 2-3 weeks in pools and wells with single application of Spherimos @ 2 ml/sq m as against 95.4% reduction @ 10 ml/sq m in irrigation channel for one week. Vectolex @ 10 ml/sq m provided 99-100% reduction of Cx. quinquefasciatus larvae up to 9 weeks in wells and 1 week in channels.