Oil fly ash as a promise larvicide against the Aedes aegypti mosquitoes.

Two environmental problems exist in some tropical and subtropical areas: the Aedes aegypti (L.) (Ae. aegypti) mosquito and thousands of tons of heavy oil fly ash (HOFA) from power plants. Herein, micro/nanoparticles of HOFA have been utilized as a larvicide against Ae. aegypti without any chemical or biological additive materials. We estimated the accumulative mortalities in the third instar after 24/48 h (h). We found that after 24 h of exposing the larvae to the HOFA microsized, the LC50 and LC90 were 0.55 and 4.87 mg/ml, respectively, while they were 0.10 and 0.36 mg/ml after 48 h. At the same time, the LC50 and LC90 were respectively 0.12 and 0.60 mg/ml after 24 h exposing the larvae to the HOFA nanosized, and they were 0.06 and 0.23 mg/ml after 48 h. These results showed that the HOFA nanoparticles as larvicides were more effective than HOFA microparticles. The microscopy images also revealed deformations such as pigmentations, segment shrinkage, larva swelling, segment body contraction, siphon swelling, intermediate stage, head deformations, and thorax swelling in the larvae exposed to the HOFA. These deformations could indicate alterations in the hormones that control the biochemistry of the larvae body. The findings of this study could suggest the possibility of using HOFA, particularly in nanosized, as a promising larvicide against the Ae. aegypti mosquito.