Submitted to: PLoS One
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/4/2014
Publication Date: 3/4/2014
Publication URL: http://handle.nal.usda.gov/10113/58622
Citation: Sikulu, M.T., Majambere, S., Khatib, B.O., Ali, A.S., Hugo, L.E., Dowell, F.E. 2014. Age prediction of resistant and susceptible Anopheles on Pemba Island, Tanzania, using near-infrared spectroscopy. PLoS One. 9(3):e90657. DOI:10.1371/journal.pone.0090657. Interpretive Summary: There are currently no rapid and cheap methods to evaluate the effectiveness of programs designed to control mosquitoes that transmit malaria. We report on the accuracy of using near-infrared spectroscopy (NIRS) to predict the age of mosquitoes that are resistant to some insecticides. Regardless of whether a mosquito had had a prior exposure to insecticides, NIRS could be used to identify mosquitoes as being young or old with 78-100% accuracy. The age structure of wild collected mosquitoes was not significantly different for susceptible and insecticide-resistant mosquitoes. This study also provides the evidence that the ability of the NIRS to predict the age of Anopheles mosquitoes may be species independent.
Technical Abstract: 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 78% 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.