Evaluating preservation methods for identifying Anopheles gambiae s.s. and Anopheles arabiensis complex mosquitoes species using near infra-red spectroscopy

Particle and Fibre Toxicology

Marta Ferreira Maia⁵  Floyd Ercell Dowell¹  Robert Andrew Wirtz⁴  Sarah Jane Moore⁵  Alex John Ntamatungiro²  Valeriana Simon Mayagaya³ 

[1] Engineering and Wind Erosion Research Unit, USDA ARS Centre for Grain and Animal Health Research, Manhattan, KS, USA;London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK;Ifakara Health Institute, Ifakara, Tanzania;Centers for Disease Control and Prevention, Atlanta 30329, GA, USA;University of Basel, Petersplatz 1, Basel, 4003, Switzerland

关键词: Malaria;    Preservation methods;    Species identification;    Anopheles arabiensis;    Anopheles gambiae s.s;    Near-infrared spectroscopy;   

Others  :  1147317
DOI  :  10.1186/s13071-015-0661-4

 received in 2014-04-23, accepted in 2015-01-14,  发布年份 2015

【 摘 要 】

Background

Near-infrared spectroscopy (NIRS) has been successfully used on fresh and RNAlater®-preserved members of the Anopheles gambiae complex to identify sibling species and age. No preservation methods other than using RNAlater® have been tested to preserve mosquitoes for species identification using NIRS. However, RNAlater® is not the most practical preservative for field settings because it is expensive, requires basic laboratory conditions for storage and is not widely available in sub-Saharan Africa. The aim of this study was to test several cheaper and more field-friendly preservation methods for identifying sibling species of the An. gambiae complex using NIRS.

Methods

In this study we describe the use of NIRS to identify sibling species of preserved An. gambiae s. s. and An. arabiensis. Mosquitoes of each species were placed in sample tubes and preserved using one of the following preservation methods: (i) refrigeration at 4°C, (ii) freezing at −20°C, (iii) drying over a silica-gel desiccant, (iv) submersion in RNAlater® at room temperature, (v) submersion in RNAlater® at 4°C, and (vi) submersion in RNAlater® at −20°C. Mosquitoes were preserved for 1, 4, 10, 32 or 50 weeks before they were scanned.

Results

Storage at 4°C was the only preservation method that, up to 32 weeks, did not result in significantly lower predicted values than those obtained from fresh insects. After 50 weeks, however, refrigerated samples did not give meaningful results. When storing for 50 weeks, desiccating samples over silica gel was the best preservation method, with a partial least squares regression cross-validation of >80%. Predictive data values were analyzed using a generalized linear model.

Conclusion

NIRS can be used to identify species of desiccated Anopheles gambiae s.s. and Anopheles arabiensis for up to 50 weeks of storage with more than 80% accuracy.

【 授权许可】

   
2015 Mayagaya et al.; licensee BioMed Central.

【 图 表 】

Figure 1.

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