Biology of Male Mosquitoes in Relation to Genetic Control Programmes

Objective:

The current mosquito SIT feasibility project at the FAO/IAEA Agriculture and Biotechnology Laboratories addresses the following issues: a) developing methods of mass rearing, b) improving sterilization, handling and release methodology, c) devising genetic and molecular methods for the production of males, and d) improving field evaluation of release mosquitoes.

Unlike female mosquitoes, that frequently imbibe blood (every 2-3 days), male mosquitoes are not blood feeders and thus do not transmit disease. They do, however, transfer genes to females during mating and are therefore logical agents for genetic control. Paradoxically, although female biology and behaviour have been intensively studied, relatively little is known about males. In particular, the specific factors that contribute to male reproductive success are virtually unknown. Nevertheless, the success of any genetic control programme will hinge on the sexual competitiveness of the mass-reared released males. Any genetic control programme is a process, beginning with colonization and mass rearing of males, followed by shipping and finally release of these males in the target population. An ongoing CRP is focusing on developing methods of mosquito mass rearing, leading to the point of release. As a logical extension, this CRP should study the factors occurring following release that may have an impact on the success of the programme. Accordingly, the objectives of this CRP are to study laboratory and field populations of adult male mosquitoes to establish the specific biological and behavioural determinants that contribute to male sexual competitiveness.

Activities:

A competitive male is defined as one that will be able to copulate wild females in the field at a rate comparable to wild males, and subsequently prevent females from laying viable eggs. The factors that contribute to this competitiveness are myriad and are determined both by natural and sexual selection, therefore this CRP focuses on male physiology and sexual behaviour, male bionomics, and male influences on the females they inseminate. Considering the current absence of sampling methods for male mosquitoes, and appropriate marking methods to study the fate of released males, research in these two areas are also included.

Specifically this CRP focuses on the biology and competitiveness of male mosquitoes in the field once they have been mass-reared and released, and strives to acquire detailed, specific and field-based information on all events in the life of adult male mosquitoes that impact their sexual competitiveness. Specific activities are: a) male physiology and behaviour, including a) male nutrition, b) spatial and temporal partitioning of sexual encounter sites, c) male copulatory success, d) male effects on females, e) male dispersal, and f) male survival rate; and B) Male sampling tools, including a) development of sampling methods for male mosquitoes, and b) marking methods for male mosquitoes.

Participants:

Sixteen participating countries: Bangladesh, Benin, Burkina Faso, Cuba, Denmark, FPL, France, Ghana, Italy, Sudan, Sweden, Syria, Trinidad and Tobago, United Kingdom, and USA.

Reports:

  • The final proceedings of the CRP are available in the Acta Tropica.