Ranchi: The Ranchi Municipal Corporation (RMC) will introduce a new insecticide for citywide fogging next week after officials found that the chemical currently in use may have lost effectiveness due to growing mosquito resistance.Additional municipal commissioner Sanjay Kumar said, “The officers have been directed to change chemical used for fogging if it is not proving to be effective enough.”The civic body has so far used 1.25% Deltamethrin ULV diluted in diesel for thermal fogging. Officials said prolonged exposure appears to have helped local mosquitoes develop tolerance, prompting the RMC to shift to a Malathion-based pesticide for thermal fogging from next week.RMC health officer Dr Kiran Kumari said malaria control guidelines usually require laboratory testing to confirm a chemical’s efficacy. However, in the absence of a local lab, the corporation decided to proactively change the chemical to counter long-term resistance.Alongside the switch, the RMC has deployed Bacillus thuringiensis israelensis (BTI), a larvicide effective in both clean and dirty water. Using nine cold fogging machines, the civic body is conducting two daily operations — spraying BTI in drains in the morning to kill larvae and applying Deltamethrin in open areas in the evening.Kumari said cold fogging gives better results than conventional thermal fogging. “While thermal fogging only impacts airborne mosquitoes, cold fogging creates a fine mist that remains suspended in the air before settling on surfaces, thereby covering a broader area,” she said.The RMC has also begun door-to-door inspections in sentinel wards 21, 22 and 23, using knapsack sprayers filled with Temephos to destroy indoor larval breeding sites. The drive will expand next week to wards 24, 25 and 26, with more sentinel wards to be identified in phases.Officials, however, said fogging alone cannot solve the mosquito problem. Kumar said preventing waterlogging remains a priority, with municipal teams continuously clearing drains to stop breeding at the source.The RMC has urged residents to keep their surroundings clean and remove standing water to curb vector-borne diseases.
