A reliable morphological method to assess the age of male Anopheles gambiae

Huho, B.J., Ng'habi, K.R., Kileen, G.F., Nkwengulila, G., Knols, B.G.J. and Ferguson, H.M. (2006) A reliable morphological method to assess the age of male Anopheles gambiae. Malaria Journal, 5(62), pp. 1-11.

Abstract

<b>Background</b> Release of genetically-modified (GM) or sterile male mosquitoes for malaria control is hampered by inability to assess the age and mating history of free-living male <i>Anopheles</i>. <b>Methods</b> Age and mating-related changes in the reproductive system of male <i>Anopheles</i> gambiae were quantified and used to fit predictive statistical models. These models, based on numbers of spermatocysts, relative size of sperm reservoir and presence/absence of a clear area around the accessory gland, were evaluated using an independent sample of mosquitoes whose status was blinded during the experiment. <b>Results</b> The number of spermatocysts in male testes decreased with age, and the relative size of their sperm reservoir increased. The presence of a clear area around accessory glands was also linked to age and mating status. A quantitative model was able to categorize males from the blind trial into age groups of young (≤ 4 days) and old (> 4 days) with an overall efficiency of 89%. Using the parameters of this model, a simple table was compiled that can be used to predict male age. In contrast, mating history could not be reliably assessed as virgins could not be distinguished from mated males. <b>Conclusion</b> Simple assessment of a few morphological traits which are easily collected in the field allows accurate age-grading of male An. gambiae. This simple, yet robust, model enables evaluation of demographic patterns and mortality in wild and released males in populations targeted by GM or sterile male-based control programmes.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ferguson, Professor Heather
• Authors: Huho, B.J., Ng'habi, K.R., Kileen, G.F., Nkwengulila, G., Knols, B.G.J., and Ferguson, H.M.
• Subjects: Q Science > QR Microbiology > QR355 Virology
• College/School: College of Medical Veterinary and Life Sciences
• Journal Name: Malaria Journal
• ISSN (Online): 1475-2875