Meeting Abstract
P2.180 Monday, Jan. 5 Thermotolerance of alternative 2La karyotypes in Anopheles gambiae ROCCA, Kyle AC*; GRAY, Emilie M; BESANSKY, Nora J; University of Notre Dame krocca@nd.edu
The primary malaria vector in Africa, Anopheles gambiae, is also well known for its ability to adapt to diverse climates and anthropogenic environments. Alternative chromosomal arrangements allow habitat expansion, exemplified by the polymorphic inversion 2La/2L+a. Field 2La frequencies reach 100% in arid savannas, while the 2L+a arrangement is predominantly found in humid environments, implicating 2La in aridity tolerance. As ability to survive high temperature exposure is an essential component of aridity tolerance, we have conducted a study of thermotolerance in two colonies of mosquitoes dissimilar solely in 2La arrangement. We hypothesize that the colony with the 2La inversion will perform better in measures of thermotolerance. This is one of two meeting papers comparing stress resistance in the 2La/2L+ populations (see Gray, Rocca and Besansky). We subjected 4th instar larvae and pupae to a heat stress (40oC water bath) for 30 to 180min and assessed survival as well as pupation success of the stressed larvae. We found that larvae responded similarly to thermal stress but that, surprisingly, 2L+ pupae were overall more thermotolerant than 2La pupae. We also tested the effect of heat hardening (HH, 1h at 38oC) on thermal tolerance of larvae and pupae. We found that, in 2La, HH significantly improved survival but not subsequent pupation success of stressed larvae. In both colonies, HH had little effect on survival of stressed pupae. Preliminary thermotolerance measurements on adults suggest no difference at this life stage. These intriguing results will be discussed in terms of evolutionary fitness advantage, and the methodology can guide further study relating genetic differences and physiological traits.
