Effective utilization period of long-lasting insecticide treated nets against Malaria vector mosquitoes and the species composition in North West Ethiopia

The study was conducted to evaluate the bioefficacy of long-lasting insecticide treated nets (LLITNs) (PermaNet ® 2.0) over time and the species composition of Anopheles mosquitoes around Bahir Dar. The space spray collection method was used to determine the species composition of indoor resting Anopheles mosquitoes in the study area. Field collected samples of household used PermaNet ® 2.0 were tested for their bioefficacy against laboratory reared An. arabiensis following the World Health Organisation standard cone test protocol. The study revealed that 75% of Anopheles mosquitoes collected from indoor location in the study area was An. arabiensis indicating that this species was the primary potential vector of malaria in the study area. The mean percentage knockdown effect of PermaNet ® 2.0 up to two years of household usage against females An. arabiensis was 100%. However, this effect decreased to 44.5% after three and half years of household use. There was no significant difference ( P > 0.5) in the mean percent mortality caused by PermaNet ® 2.0 after six months and two years household usage (92.5% and 84%, respectively). However, under laboratory conditions there was recorded a markedly significant reduction ( P < 0.01) in the mean percent mortality of females An. arabiensis exposed to PermaNet ® 2.0 that has been used for three and half years (27%). Close monitoring on the feeding and resting behavior of malaria vector mosquitoes and awareness creation on the proper utilization of the bed net need to be conducted to check and maintain its feasibility as part of integrated malaria vector management. Keywords/phrases: Anopheles arabiensis, Bioefficacy, Long-lasting insecticide treated nets, PermaNet Ethiop. J. Biol. Sci ., 10(1): 103-110, 2011