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Using a near-infrared spectrometer to estimate the age of Anopheles mosquitoes exposed to pyrethroids

Sikulu, Maggy T., Majambere, Silas, Khatib, Bakar O., Ali, Abdullah S., Hugo, Leon E., Dowell, Floyd E.
Plos One 2014 v.9 no.3 pp. e90657
Anopheles, adults, age structure, environmental exposure, environmental factors, insect larvae, insecticides, near-infrared spectroscopy, pyrethrins, traps
We report on the accuracy of using near-infrared spectroscopy (NIRS) to predict the age of Anopheles mosquitoes reared from wild larvae and a mixed age-wild adult population collected from pit traps after exposure to pyrethroids. The mosquitoes reared from wild larvae were estimated as ,7 or $7 d old with an overall accuracy of 79%. The age categories of Anopheles mosquitoes that were not exposed to the insecticide papers were predicted with 8% accuracy whereas the age categories of resistant, susceptible and mosquitoes exposed to control papers were predicted with 82%, 78% and 79% accuracy, respectively. The ages of 85% of the wild-collected mixed-age Anopheles were predicted by NIRS as #8 d for both susceptible and resistant groups. The age structure of wild-collected mosquitoes was not significantly different for the pyrethroid-susceptible and pyrethroid-resistant mosquitoes (P = 0.210). Based on these findings, NIRS chronological age estimation technique for Anopheles mosquitoes may be independent of insecticide exposure and the environmental conditions to which the mosquitoes are exposed.