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United States Department of Agriculture

Agricultural Research Service

Research Project: PRESERVATION, ENHANCEMENT, AND MEASUREMENT OF GRAIN QUALITY AND MARKETABILITY

Location: Stored Product Insect and Engineering Research

Title: The influence of physiological status on age prediction of Anopheles arabiensis using near infra-red spectroscopy

Authors
item Ntamatungiro, Alex -
item Mayagaya, Valeriana -
item Rieben, Stefan -
item Moore, Sarah -
item Dowell, Floyd
item Maia, Marta -

Submitted to: Parasites & Vectors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 9, 2013
Publication Date: October 14, 2013
Repository URL: http://dx.doi.org/10.1186/1756-3305-6-298
Citation: Ntamatungiro, A., Mayagaya, V., Rieben, S., Moore, S.J., Dowell, F.E., Maia, M. 2013. The influence of physiological status on age prediction of Anopheles arabiensis using near infra-red spectroscopy. Parasites & Vectors. 6:298. DOI:10.1186/1756-3305-6-298.

Interpretive Summary: Determining the age of mosquitoes that transmit malaria is essential for evaluating the impact of methods that reduce the survival of wild mosquito populations. Near infra-red spectroscopy (NIRS) is a simple and non-destructive method that has been used to determine the age and species of Anopheles gambiae s.l. by analyzing differences in absorption spectra. The spectra are affected by biochemical changes that occur during the life of a mosquito. To better understand these changes, we evaluated the influence of mosquito physiological status on NIR spectra. Mosquitoes of the same chronological age, but at different physiological stages, were scanned and compared. We observed that older insects tend to be predicted as being physiologically more mature. NIRS could be used to predict physiological status but with considerable overlap within physiological stages. Our results shows that users who wish to use NIR technology to predict the age of field-caught Anopheles gambiae s.l should use a calibration that includes diverse ages and physiological stages to increase the robustness and accuracy of the model.

Technical Abstract: Determining the age of malaria vectors is essential for evaluating the impact of interventions that reduce the survival of wild mosquito populations and for estimating changes in vectorial capacity. Near infra-red spectroscopy (NIRS) is a simple and non-destructive method that has been used to determine the age and species of Anopheles gambiae s.l. by analyzing differences in absorption spectra. The spectra are affected by biochemical changes that occur during the life of a mosquito and could be influenced by senescence and also the life history of the mosquito, i.e., mating, blood feeding and egg- laying events. To better understand these changes, we evaluated the influence of mosquito physiological status on NIR energy absorption spectra. Mosquitoes were kept in individual cups to permit record keeping of each individual insect’s life history. Mosquitoes of the same chronological age, but at different physiological stages, were scanned and compared using cross-validations. We observed a slight trend within some physiological stages that suggest older insects tend to be predicted as being physiologically more mature. NIRS could be used to predict physiological status but with considerable overlap within physiological stages. However, it was advantageous to include mosquitoes of different physiological stages in calibrations, as it increases the robustness of the model resulting in better age predictions. There is considerable accordance between physiological and chronological age of malaria vector, thus, Entomologists that wish to use NIR technology to predict the age of field-caught Anopheles gambiae s.l from their study area should use a calibration done from their field strain using diverse ages and physiological stages to increase the robustness and accuracy of the predictions.

Last Modified: 11/1/2014
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