Assessment of larvicidal, growth-suppressing, and developmentaltering bioefficacy of Ageratum houstonianum against Aedes aegypti (L.).

Abstract

Background objectives: Aedes aegypti is a major vector responsible for spreading dengue, chikungunya, yellow fever, and Zika viruses worldwide. These illnesses have increased globally due to climate and environmental changes. Vector control and management are the principal tactics for combating mosquitoes-borne diseases in the absence of an effective vaccine. The study aimed to ascertain bioactivities of Ageratum houstonianum leaf acetone extract (AhLAE) against Aedes aegypti.

Methods: Bioefficacy of AhLAE was tested against fourth instar larvae (L4) of Ae. aegypti using standard WHO protocol. The mortality, growth, and development of larvae, pupae and adults were recorded after exposure to the extract.

Results: The AhLAE showed larvicidal activity against L4 with LC50 and LC90 values of 401.88 and 691.24 mg/L, respectively. The mortality of the larvae further increased on subsequent days. The AhLAE caused a significant reduction in pupae formation and adult emergence. It also increased the larval duration of L4 and development duration of the pupa formed from the treated L4, indicating its growth-suppressing effects. The impact of the AhLAE was dose-dependent; high concentrations caused reduction in survival and growth of L4. Consequently, the L4-pupal and L4-adult growth indexes decreased. Additionally, the AhLAE induced developmental anomalies in the form of larva-pupa (L-P) intermediates.

Interpretation conclusion: The study found that the AhLAE exhibited larvicidal, growth-suppressing, and development-altering activities against Ae. aegypti. The findings suggest the potential of AhALE as a natural insecticidal agent for controlling mosquitoes.