A Novel Model of Pathogenesis of Metarhizium anisopliae Propagules through the Midguts of Aedes aegypti Larvae

Ricardo de Oliveira Barbosa Bitencourt; Jacenir Reis Dos Santos-Mallet; Carl Lowenberger; Adriana Ventura; Patrícia Silva Gôlo; Vânia Rita Elias Pinheiro Bittencourt; Isabele da Costa Angelo

doi:10.3390/insects14040328

A Novel Model of Pathogenesis of Metarhizium anisopliae Propagules through the Midguts of Aedes aegypti Larvae

Insects. 2023 Mar 28;14(4):328. doi: 10.3390/insects14040328.

Authors

Ricardo de Oliveira Barbosa Bitencourt¹, Jacenir Reis Dos Santos-Mallet^{2

3

4}, Carl Lowenberger⁵, Adriana Ventura⁶, Patrícia Silva Gôlo⁷, Vânia Rita Elias Pinheiro Bittencourt⁷, Isabele da Costa Angelo⁸

Affiliations

¹ Graduate Program in Veterinary Sciences, Veterinary Institute, Federal Rural University of Rio de Janeiro, Seropédica 23890-000, RJ, Brazil.
² Oswaldo Cruz Foundation, IOC-FIOCRUZ-RJ, Rio de Janeiro 21040-900, RJ, Brazil.
³ Oswaldo Cruz Foundation, IOC-FIOCRUZ-PI, Teresina 64001-350, PI, Brazil.
⁴ Laboratory of Surveillance and Biodiversity in Health, Iguaçu University-UNIG, Nova Iguaçu 28300-000, RJ, Brazil.
⁵ Centre for Cell Biology, Development and Disease, Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
⁶ Department of Animal Biology, Institute of Health and Biological Sciences, Federal Rural University of Rio de Janeiro, Seropédica 23890-000, RJ, Brazil.
⁷ Department of Animal Parasitology, Veterinary Institute, Federal Rural University of Rio de Janeiro, Seropédica 23890-000, RJ, Brazil.
⁸ Department of Epidemiology and Public Health, Veterinary Institute, Federal Rural University of Rio de Janeiro, Seropédica 23890-000, RJ, Brazil.

Abstract

We assessed the effect of the entomopathogenic fungus Metarhizium anisopliae against Aedes aegypti. Conidia of M. anisopliae strains CG 489, CG 153, and IBCB 481 were grown in Adamek medium under different conditions to improve blastospore production. Mosquito larvae were exposed to blastospores or conidia of the three fungal strains at 1 × 10⁷ propagules mL^-1. M. anisopliae IBCB 481 and CG 153 reduced larval survival by 100%, whereas CG 489 decreased survival by about 50%. Blastospores of M. anisopliae IBCB 481 had better results in lowering larval survival. M. anisopliae CG 489 and CG 153 reduced larval survival similarly. For histopathology (HP) and scanning electron microscopy (SEM), larvae were exposed to M. anisopliae CG 153 for 24 h or 48 h. SEM confirmed the presence of fungi in the digestive tract, while HP confirmed that propagules reached the hemocoel via the midgut, damaged the peritrophic matrix, caused rupture and atrophy of the intestinal mucosa, caused cytoplasmic disorganization of the enterocytes, and degraded the brush border. Furthermore, we report for the first time the potential of M. anisopliae IBCB 481 to kill Ae. aegypti larvae and methods to improve the production of blastospores.

Keywords: blastospores; conidia; entomopathogenic fungi; mosquitoes.

Grants and funding

Financial support was provided by the Natural Sciences and Engineering Research Council of Canada Discovery Grants (RGPIN261940 and 261940 to C.L).