Arthropods (Sep 2022)
Evaluating the efficacy of Olyset® nets in the laboratory and trap surveillance of Aedes mosquitoes
Abstract
With Chikungunya and Zika in the Philippines, there is an urgent need for effective methods to control Aedes aegypti and Aedes albopictus in as much as these mosquitoes are not only vectors of Dengue but also of Chikungunya and Zika. Evaluation of the efficacy of Olyset® nets was done in two approaches: (1) laboratory WHO cone bioassay on Olyset® net and (2) comparative mosquito trap surveillance of dengue vector mosquitoes in DepEd classrooms with and without Olyset® nets. During laboratory cone bioassay, % knockdown and % mortalities were recorded for Ae. aegypti and Ae. albopictus. Penetrability tests were also done on Olyset® nets. During comparative mosquito trap surveillance, the total Aedes capture in classrooms with Olyset® nets was compared to Aedes capture in classrooms without Olyset® nets. Ae. aegypti showed A 54% percent knockdown and 63% mortality Ae. albopictus showed 77% knockdown, and 79% mortality was shown in cone bioassay of Olyset® nets. Penetrability test on Olyset® nets showed 35% Ae. aegypti and 34% Ae. albopictus crossed the nets, but only 10% in Ae. aegypti and 6% in Ae. albopictus survived the crossing. Female adult and larval Aedes capture differed significantly between classrooms with Olyset® nets and those without Olyset® nets. But the observed lack of screen doors and poor physical integrity of Olyset® nets in classrooms might compromise its efficacy. Based on WHO 98% susceptibility test criterion, there was probable insecticide resistance in Aedes mosquitoes to 2% permethrin in Olyset® nets. In the classroom mosquito surveillance, significant differences of Aedes capture between classroom groups may have been obtained, but other observations indicated compromised efficacy of the Olyset® nets.
