, 2013). Variability in the studied developmental patterns could be the result of an absence of directional selection or can reflect a selection process to the local environment ( Bradshaw et al., 2004). As this study’s experimental rearing temperature corresponds to the natural coldest developmental conditions on La Reunion Island shores, the tropical strain was reared under a more stressful Vincristine datasheet environment than the temperate strain
whose fitness is optimized for this average temperature. However, even among tropical strains of A. aegypti, developmental rates have been demonstrated to be heterogeneous under the same temperature ( Couret and Benedict, 2014). Different larval developmental rates between populations have previously been observed www.selleckchem.com/JNK.html in other mosquito species like A. (Oc.) triseriatus ( Holzapfel and Bradshaw, 1981), but not in A. albopictus ( Waldock
et al., 2013). This underlines the need to compare several temperate and tropical strains in order to confirm our observations. Aedes species are particularly exposed to desiccation, and its serosal cuticle development is more effective than in other mosquito genera (Vargas et al., 2014). Interestingly, only the serosal cuticle’s complete secretion took place faster in our tropical strain as compared to our temperate strain. The first hypothesis to explain this kinetic difference is that this protection mechanism against a dried-up environment must be subject to a strong MRIP selective pressure, especially in the tropics where the threat of death by desiccation is extreme (Tauber et al., 1986). However A. albopictus eggs are laid in outdoor water containers likely to dry up, and most eggs in diapause process are laid during the favorable season when average temperature is still high in temperate area. The additional delay in the formation of serosal cuticle generated by diapause preparation incurs a longer period of sensitivity to desiccation in a context of strong evaporation. Thus the
induction of diapause syndrome could have hazardous effects on eggs, even if diapause-programmed eggs later offset this risk notably with a higher quantity of surface lipids on the chorion which increases desiccation resistance ( Sota and Mogi, 1992a and Urbanski et al., 2010a). The serosal cuticle is an important structure protecting from desiccation but not the only one ( Rezende et al., 2008). The second hypothesis is that tropical strains developed other structural and metabolic mechanisms to improve the egg’s waterproof quality, and counterbalance a more rapid but potentially weaker or thinner serosal cuticle. This hypothesis is supported by the presence of a higher quantity of surface hydrocarbons on tropical eggs than temperate eggs ( Urbanski et al., 2010a). Temperate strains would favor the production of a stronger or improved serosal cuticle than tropical strains, which requires a prolonged period of formation.