Abstract:
The increasing resistance of Aedes aegtpti mosquitoes to commonly used insecticides
exacerbate the challenges faced by vector control programs, highlighting the urgent
need for enhanced monitoring efforts. Particularly, concerning is the lack of recent
literature addressing insecticide resistance within Batticaloa district, emphasizing the
critical necessity for comprehensive research in this area. Therefore, this study aimed
to investigate the prevalence of insecticide resistance and susceptibility among Aedes
aegtpti populations in Batticaloa district, Sri Lanka. From August2023 to February
2024,lawal surveys were conducted across three distinct Medical Officer of Health
(MOH) areas: Batticaloa, Eravur, and Koralai Patru Central (KPC). Bioassays
employing three different insecticides - deltamethrin, malathion and permethrin - were
conducted onadultAe. aegtpti mosquitoes using standardizedprotocols outlined by the
World Health Organization (WHO). Concurrently. larval indices including the House
index (HI), Breteau index (BI) and Container index (CI) were calculated to assess the
larval infestation levels across the MOH areas. The comprehensive examination of
4,458 potential breeding sites with water retention revealed 138 Ae. aeg,tpti positive
containers within Batticaloa district. A total of 1,082 Ae. aeg,,pti mosquito larvae were
identified during the study period. The values of HI were ranged from 16.67 to 28, BI
were from 23 to 38 and CI were ranged from,2.40 to 3.97 . Susceptibility was observed
when percent mortality ranged from 98 to i00oh, while incipient insecticide resistance
was indicated by mortality rates between 80 and 97o/o. In conclusion, this study
underscores the pressing need for sustained monitoring and intervention strategies to
combat Ae. aeg,pti-mediated dengue transmission in Batticaloa district. The observed
variations in larval indices and insecticide susceptibility highlight the dynamic nature
of vector control challenges. Addressing these issues requires collaborative efforts
involving policymakers, healthcare authorities and local communities to implement
targeted interventions aimed at mitigating insecticide resistance and reducing
mosquito-bome disease burden.
