Potential use of a combined sterile insect technique (SIT) and Wolbachia-based approach for the control of the dengue vector Aedes albopictus in Sri Lanka

Postgraduate student
N. D. Asha Dilrukshi Wijegunawardana, Scientific Assistant/PhD Student , Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka.

Supervisors

• Prof. Y. I. N. Silva Gunawardene, Professor in Molecular Medicine, Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka.
• Prof. W. Abeyewickreme, Professor in Parasitology, Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka.
• Prof. T. G. A. N. Chandrasena, Associate Professor in Parasitology, Department of Parasitology, Faculty of Medicine, University of Kelaniya, Sri Lanka.
• Prof. Ranil S. Dassanayake, Professor in Molecular Biology and Biochemistry Department of Chemistry, Faculty of Science, University of Colombo, Sri Lanka.
• Prof. Kostas Bourtzis, Molecular Biologist, International Atomic Energy Agency (IAEA), Vienna.
• Prof. Zhiyong Xi, Director, Sun Yat-Sen University - Michigan State University Joint Center of Vector Control for Tropical Diseases, China.

General objective of the project:
To assess the effectiveness of a combined SIT and Wolbachia based approach for control of Aedes albopictus as an intervention in dengue vector management in Sri Lanka

Project summery

The current research study will focus on the possibility of using a novel and environmental friendly strategy combining the sterile insect technique (SIT) and a Wolbachia-based approach (Incompatible Insect Technique, IIT) in Aedes albopictus population control efforts as an additional tool in the integrated dengue vector control in Sri Lanka. The above strategy uses Wolbachia, an obligate intracellular bacterium that lives inside insects and is transmitted vertically from mother to offspring (some Wolbachia strains have been shown to block the transmission of dengue virus). Releasing male mosquitoes harboring a different Wolbachia strain from that present in a wild population will also produce reproductive incompatibilities. Releasing Wolbachia-infected females (and males), the infection will spread via the action of cytoplasmic incompatibility (CI) as well as the ability to block the pathogen. Over time scientists have selected strains of Wolbachia that have a strong dengue viral transmission blocking effect combined with stable establishment in wild vector population. Our strategy will focus on the suppression of Ae. albopictus population by releasing sterile male mosquitoes in large scale; so, the accidental release of infected females in adequate numbers may result in the replacement of the targeted population with a population carrying the Wolbachia infection of the released mosquitoes if reared females are compatible with the wild males. Thus the successful implementation of the above method in large scale requires an effective sex separation system for Ae. albopictus mosquitoes which is not available presently. In that sense a better solution would be the integration of irradiation with the above Wolabachia-based strategy. Application of irradiation at a dose which would sterilize the females without affecting the quality of the released males could ensure that any accidental release of females will not result in fertile crosses and viable offspring (Sharma et al., 1979; Arunachalam and Curtis, 1985; Bourtzis and Robinson, 2006; Bourtzis et al. 2014). Complete female sterility in Aedes albopictus can be induced by the application of 28 Gy irradiation, a dose that does not affect the male fitness (D. Zhang, Z. Xi, J. Gilles and K. Bourtzis, unpublished data). By combining irradiation with CI, the sterility of released males is due to both Wolbachia and irradiation while the female sterility is only due to irradiation. This combined strategy could in principle be applied in control of Ae. albopictus mosquito vector control since it does not deviate much from the single Wolbachia-based approach. Thus Wolbachia-infected mosquitoes treated with SIT can be easily introduced in the field and thereby provide a low-cost, long-term solution to dengue control. The proposed study will explore the possibility of using a combined SIT and Wolbachia-based population suppression approach in Aedes albopictus dengue vector control as an additional tool in integrated vector management in Sri Lanka.

Publications that have been done under the project

• N. D. A. D. Wijegunawardana, N. Gunathilaka, W. Abeyewickreme, Y. I. Nilmini Silva Gunawardene, R. S. Dasannayaka, N. Chandrasena (2015) Establishment and maintenance of laboratory colonies of Aedes albopictus mosquitoes. Abstract has been accepted for the oral presentation at the proceedings of the Peradeniya University International Research Sessions in November, 2015.