Four mosquito densovirus strains were assayed for mortality and infectivity against Aedes aegypti larvae from different geographic regions. The viral titers were quantified by real-time PCR using TaqMan technology. Firstinstar larvae were exposed to the same titer of each densovirus strain for 48 hours. All strains of densoviruses exhibited larvicidal activity and caused more than 80% mortality and infectivity in the three mosquito strains. AalDNV-exposed larvae had the highest mortality rate. The mean time to death of AalDNV-exposed larvae was shorter than other DNVs-exposed larvae. We can conclude that different densovirus strains exhibit some variations in their pathogenicity to different populations of Ae. aegypti mosquitoes. A few mosquitoes from Chachoengsao and Bangkok exposed to AeDNV and AThDNV survived to the adult stage to lay eggs and showed 22% to 50% vertical transmission in the F1 generation. Phylogenetic analysis of four densovirus strains indicated that mosquito densoviruses are separated into two distinct clades.