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United States Department of Agriculture

Agricultural Research Service


Location: Stored Product Insect and Engineering Research

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

item Sikulu, Maggy
item Majambere, Silas
item Khatib, Bakar
item Ali, Abdulla
item Hugo, Leon
item Dowell, Floyd

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2014
Publication Date: 3/4/2014
Publication URL:
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.

Last Modified: 07/21/2017
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