author(s)
Swagatika Misra and Santosh Kumar Panda

abstract
Field and laboratory experiments were conducted to investigate twelve insecticides comprising granular and spray formulations of imidacloprid, cartap hydrochloride, fipronil, chlorantraniliprole along with carbofuran, phorate and monocrotophos as insecticidal checks for their effects on soil micro flora in rice ecosystem during kharif and rabi 2015. The populations of micro flora were clearly dependent on the type of insecticide formulation and the number of days after application. Insecticidal applications at 20 and 50 DAT demonstrated a decline in soil microbial populations at 7 days after application, which gradually recovered with a gradual built up at 14 and 21 days after. Granules in general showed a greater negative effect on soil micro flora compared to their spray counterpart. At initial stage of application of insecticides the population of micro flora reduced in an exponential manner, although it was seen to recover after 21 days after application of insecticides. The data collected during kharif ‘2014 visibly indicated that carbofuran 3G and phorate 10G were the most favourable granules for augmentation of microbial population. The granular insecticides that helped in boosting up the population of bacteria and actinomycetes were carbofuran and phorate along with sprayable imidacloprid and chlorantraniliprole during both kharif and rabi seasons. All the granular treatments were detrimental on fungal population and amongst the sprayable ones; cartap, fipronil and chlorantraniliprole were the ones having less adverse effect on fungal population.