Analysis of near infrared spectra for age-grading of wild populations of Anopheles gambiae
Abstract Background Understanding the age-structure of mosquito populations, especially malaria vectors such as Anopheles gambiae, is important for assessing the risk of infectious mosquitoes, and how vector control interventions may impact this risk. The use of near-infrared spectroscopy (NIRS) for...
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doaj-c9d37857c1774bbaafa68a3634e00e4a2020-11-25T01:53:24ZengBMCParasites & Vectors1756-33052017-11-0110111310.1186/s13071-017-2501-1Analysis of near infrared spectra for age-grading of wild populations of Anopheles gambiaeBenjamin J. Krajacich0Jacob I. Meyers1Haoues Alout2Roch K. Dabiré3Floyd E. Dowell4Brian D. Foy5Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State UniversityArthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State UniversityArthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State UniversityDirection Régionale de l’Ouest (DRO), Institut de Recherche en Sciences de la Santé (IRSS)Stored Product Insect and Engineering Research Unit, United States Department of Agriculture/Agricultural Research Services, Center for Grain and Animal Health ResearchArthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State UniversityAbstract Background Understanding the age-structure of mosquito populations, especially malaria vectors such as Anopheles gambiae, is important for assessing the risk of infectious mosquitoes, and how vector control interventions may impact this risk. The use of near-infrared spectroscopy (NIRS) for age-grading has been demonstrated previously on laboratory and semi-field mosquitoes, but to date has not been utilized on wild-caught mosquitoes whose age is externally validated via parity status or parasite infection stage. In this study, we developed regression and classification models using NIRS on datasets of wild An. gambiae (s.l.) reared from larvae collected from the field in Burkina Faso, and two laboratory strains. We compared the accuracy of these models for predicting the ages of wild-caught mosquitoes that had been scored for their parity status as well as for positivity for Plasmodium sporozoites. Results Regression models utilizing variable selection increased predictive accuracy over the more common full-spectrum partial least squares (PLS) approach for cross-validation of the datasets, validation, and independent test sets. Models produced from datasets that included the greatest range of mosquito samples (i.e. different sampling locations and times) had the highest predictive accuracy on independent testing sets, though overall accuracy on these samples was low. For classification, we found that intramodel accuracy ranged between 73.5–97.0% for grouping of mosquitoes into “early” and “late” age classes, with the highest prediction accuracy found in laboratory colonized mosquitoes. However, this accuracy was decreased on test sets, with the highest classification of an independent set of wild-caught larvae reared to set ages being 69.6%. Conclusions Variation in NIRS data, likely from dietary, genetic, and other factors limits the accuracy of this technique with wild-caught mosquitoes. Alternative algorithms may help improve prediction accuracy, but care should be taken to either maximize variety in models or minimize confounders.http://link.springer.com/article/10.1186/s13071-017-2501-1AnophelesMosquitoesAgingSpectroscopy |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Benjamin J. Krajacich Jacob I. Meyers Haoues Alout Roch K. Dabiré Floyd E. Dowell Brian D. Foy |
spellingShingle |
Benjamin J. Krajacich Jacob I. Meyers Haoues Alout Roch K. Dabiré Floyd E. Dowell Brian D. Foy Analysis of near infrared spectra for age-grading of wild populations of Anopheles gambiae Parasites & Vectors Anopheles Mosquitoes Aging Spectroscopy |
author_facet |
Benjamin J. Krajacich Jacob I. Meyers Haoues Alout Roch K. Dabiré Floyd E. Dowell Brian D. Foy |
author_sort |
Benjamin J. Krajacich |
title |
Analysis of near infrared spectra for age-grading of wild populations of Anopheles gambiae |
title_short |
Analysis of near infrared spectra for age-grading of wild populations of Anopheles gambiae |
title_full |
Analysis of near infrared spectra for age-grading of wild populations of Anopheles gambiae |
title_fullStr |
Analysis of near infrared spectra for age-grading of wild populations of Anopheles gambiae |
title_full_unstemmed |
Analysis of near infrared spectra for age-grading of wild populations of Anopheles gambiae |
title_sort |
analysis of near infrared spectra for age-grading of wild populations of anopheles gambiae |
publisher |
BMC |
series |
Parasites & Vectors |
issn |
1756-3305 |
publishDate |
2017-11-01 |
description |
Abstract Background Understanding the age-structure of mosquito populations, especially malaria vectors such as Anopheles gambiae, is important for assessing the risk of infectious mosquitoes, and how vector control interventions may impact this risk. The use of near-infrared spectroscopy (NIRS) for age-grading has been demonstrated previously on laboratory and semi-field mosquitoes, but to date has not been utilized on wild-caught mosquitoes whose age is externally validated via parity status or parasite infection stage. In this study, we developed regression and classification models using NIRS on datasets of wild An. gambiae (s.l.) reared from larvae collected from the field in Burkina Faso, and two laboratory strains. We compared the accuracy of these models for predicting the ages of wild-caught mosquitoes that had been scored for their parity status as well as for positivity for Plasmodium sporozoites. Results Regression models utilizing variable selection increased predictive accuracy over the more common full-spectrum partial least squares (PLS) approach for cross-validation of the datasets, validation, and independent test sets. Models produced from datasets that included the greatest range of mosquito samples (i.e. different sampling locations and times) had the highest predictive accuracy on independent testing sets, though overall accuracy on these samples was low. For classification, we found that intramodel accuracy ranged between 73.5–97.0% for grouping of mosquitoes into “early” and “late” age classes, with the highest prediction accuracy found in laboratory colonized mosquitoes. However, this accuracy was decreased on test sets, with the highest classification of an independent set of wild-caught larvae reared to set ages being 69.6%. Conclusions Variation in NIRS data, likely from dietary, genetic, and other factors limits the accuracy of this technique with wild-caught mosquitoes. Alternative algorithms may help improve prediction accuracy, but care should be taken to either maximize variety in models or minimize confounders. |
topic |
Anopheles Mosquitoes Aging Spectroscopy |
url |
http://link.springer.com/article/10.1186/s13071-017-2501-1 |
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