Relationship of larval desiccation to Anopheles gambiae Giles and An. arabiensis Patton survival

The relationship between mosquito 4th instar larval desiccation and survival to adulthood was explored by three methods in the laboratory. Two colonies of Anopheles arabiensis and one of Anopheles gambiae were studied. We found significant differences in tolerance to desiccation among all three stocks suggesting an intra- and interspecific genetic component to desiccation tolerance. An. arabiensis KGB, originating from Zimbabwe about 1975, had a much-reduced desiccation tolerance compared to An. gambiae G3, colonized in the Gambia in 1975, and An. arabiensis DONGOLA which originated in Sudan in 2004. Individuals of the G3 stock survived desiccation of times up to 40 min with survival of 0.52. The degree of difference in tolerance between G3 and DONGOLA was smallest and was detected by one of three experimental methods. Mass losses of individuals that were weighed individually and survived to adulthood averaged 27% and 29% for G3 and DONGOLA and 20% for the less tolerant KGB stock, respectively. Such differences in survival in transiently dry larval habitats may account in part for differences in the distribution of these species and karyotypes.