Article
Serosal cuticle formation and distinct degrees of desiccation resistance in embryos of the mosquito vectors Aedes aegypti, Anopheles aquasalis and Culex quinquefasciatus
Registro en:
VARGAS, Helena Carolina Martins et al. Serosal cuticle formation and distinct degrees of desiccation resistance in embryos of the mosquito vectors Aedes aegypti, Anopheles aquasalis and Culex quinquefasciatus. Journal of Insect Physiology, n.62, p. 54-60, 2014.
0022-1910
10.1016/j.jinsphys.2014.02.001
Autor
Vargas, Helena Carolina Martins
Farnesi, Luana Cristina
Martins, Ademir Jesus
Valle, Denise
Rezende, Gustavo Lazzaro
Resumen
Given their medical importance, mosquitoes have been studied as vectors of parasites since the late
1800’s. However, there are still many gaps concerning some aspects of their biology, such as embryogenesis.
The embryonic desiccation resistance (EDR), already described in Aedes and Anopheles gambiae mosquitoes,
is a peculiar trait. Freshly laid eggs are susceptible to water loss, a condition that can impair their
viability. EDR is acquired during embryogenesis through the formation of the serosal cuticle (SC), protecting
eggs from desiccation. Nevertheless, conservation of both traits (SC presence and EDR acquisition)
throughout mosquito evolution is unknown. Comparative physiological studies with mosquito embryos
from different genera, exhibiting distinct evolutionary histories and habits is a feasible approach. In this
sense, the process of EDR acquisition of Aedes aegypti, Anopheles aquasalis and Culex quinquefasciatus at
25 C was evaluated. Completion of embryogenesis occurs in Ae. aegypti, An. aquasalis and Cx. quinquefasciatus
at, respectively 77.4, 51.3 and 34.3 hours after egg laying, Cx. quinquefasciatus embryonic development
taking less than half the time of Ae. aegypti. In all cases, EDR is acquired in correlation with SC
formation. For both Ae. aegypti and An. aquasalis, EDR and SC appear at 21% of total embryonic development,
corresponding to the morphological stage of complete germ band elongation/beginning of germ
band retraction. Although phylogenetically closer to Ae. aegypti than to An. aquasalis, Cx. quinquefasciatus
acquires both EDR and serosal cuticle later, with 35% of total development, when the embryo already progresses
to the middle of germ band retraction. EDR confers distinct egg viability in these species. While
Ae. aegypti eggs demonstrated high viability when left up to 72 hours in a dry environment, those of An.
aquasalis and Cx. quinquefasciatus supported these conditions for only 24 and 5 hours, respectively. Our
data suggest that serosa development is at least partially uncoupled from embryo development and that,
depending upon the mosquito species, EDR bestows distinct levels of egg viability.