Mortality and malformation effects of boric acid against larval stage of Aedes aegypti (Culicidae: Diptera)

Mosquitoes, the disquieting insect, can transmit pathogens more than any other insect, and they can cause fatal diseases to both humans and animals in their environment. With the increasing problem of pesticide resistance spreading in the field, substantial efforts are being made at the international level to develop environmental insecticides to reduce these mosquito populations or limit their potential to transmit disease. In this preliminary study, mortality and malformation effects of seven concentrations (700, 1000, 1200, 1500, 2000, 2500, and 3000 ppm) of boric acid were evaluated against the 4th larval stage of Aedes aegypti after 24 h of exposure. Malformed and dead larvae were photographed under the microscope with a digital camera connected to a computer stereo-dissecting microscope. Our results showed that the lethal concentrations (LC50 and LC90) were 1312.49 and 2578.26, respectively. Also, the results showed malformation effects against treated larvae with boric acid compared to the control group. These malformations manifested in albino pupa, Pigmentation, Larval-pupal intermediate, Black coloration at the posterior end, Opaque swelling on the thorax, Segment contraction, Deformed cuticles, black coloration at the posterior end, and nick elongation. Boric acid is less toxic than synthesized insecticides, and in low concentrations, it causes mortality and malformation effects against larval stages of A. aegypti. Further, the use of boric acid as a safe method for controlling larval stages of A. aegypti can be recommended as it is available, cost-effective, and less harmful to humans, animals, and the environment.