Near-infrared spectroscopy as a complementary age grading and species identification tool for African malaria vectors

• Main Authors: Dowell Kayla M, Ryan Peter A, Hugo Leon E, Killeen Gerry F, Sikulu Maggy, Wirtz Robert A, Moore Sarah J, Dowell Floyd E
• Format: Article
• Language: English
• Published: BMC 2010-06-01
• Series: Parasites & Vectors
• Online Access: http://www.parasitesandvectors.com/content/3/1/49

<p>Abstract</p> <p>Near-infrared spectroscopy (NIRS) was recently applied to age-grade and differentiate laboratory reared <it>Anopheles gambiae sensu strico </it>and <it>Anopheles arabiensis </it>sibling species of <it>Anopheles gambiae sensu lato </it>complex. In this study, we report further on the accuracy of this tool for simultaneously estimating the age class and differentiating the morphologically indistinguishable <it>An. gambiae s.s</it>. and <it>An. arabiensis </it>from semi-field releases and wild populations. Nine different ages (1, 3, 5, 7, 9, 11, 12, 14, 16 d) of <it>An. arabiensis </it>and eight different ages (1, 3, 5, 7, 9, 10, 11, 12 d) of <it>An. gambiae s.s</it>. maintained in 250 × 60 × 40 cm cages within a semi-field large-cage system and 105 wild-caught female <it>An. gambiae s.l.</it>, were included in this study. NIRS classified female <it>An. arabiensis </it>and <it>An. gambiae s.s</it>. maintained in semi-field cages as <7 d old or ≥7 d old with 89% (n = 377) and 78% (n = 327) accuracy, respectively, and differentiated them with 89% (n = 704) accuracy. Wild caught <it>An. gambiae s.l</it>. were identified with 90% accuracy (n = 105) whereas their predicted ages were consistent with the expected mean chronological ages of the physiological age categories determined by dissections. These findings have importance for monitoring control programmes where reduction in the proportion of older mosquitoes that have the ability to transmit malaria is an important outcome.</p>