Semi-field evaluation of spontaneous hatching and egg mortality in <i>Aedes</i> spp. (Diptera: Culicidae) in northeastern Argentina

Aedes albopictus (Skuse, 1895) has limited records in Argentina and, at its southernmost range, occurs mainly in natural environments, while Aedes aegypti (Linnaeus, 1762) dominates urban areas. This segregation suggests that environmental conditions may limit the expansion of Ae. albopictus into urban habitats. The study evaluates spontaneous egg hatching and egg mortality of both species to determine whether urban conditions constrain Ae. albopictus and whether it has the potential to colonize these environments. Two semi-field experiments were carried out in Santo Tomé, Corrientes Province (Argentina). In Experiment 1, eggs were exposed to ambient conditions in a natural and urban environment to assess spontaneous egg hatching. In Experiment 2, eggs were protected from precipitation to evaluate mortality. In the urban environment, both spontaneous hatching and egg mortality were higher in Ae. albopictus than in Ae. aegypti. In the natural environment, Ae. albopictus showed higher spontaneous hatching, but mortality rates did not differ significantly between the two species. Furthermore, hatching rates were associated with precipitation in both species, while Ae. albopictus mortality was associated with temperature. In contrast, Ae. aegypti mortality did not present an association with meteorological variables. Results indicate that rainfall can trigger hatching without immersion, increasing mortality risk. Combined with its higher intrinsic mortality, these findings suggest that temperature may limit the urban expansion of Ae. albopictus in southern regions. The findings contribute to understanding the ecological mechanisms underlying environmental segregation between these species and their potential for urban colonization.