Comparative evaluation of mycobiota of Aedes albopictus and Culex quinquefasciatus larave and larvicidal potential of associated entomopathogenic fungi

Abstract

Fungi influence mosquito survival, development, and population dynamics through symbiotic to pathogenic interactions. This study aimed to characterise and compare the fungal communities associated with larvae of Aedes and Culex mosquitoes, and to evaluate the entomopathogenic potential of common fungal species isolated from both mosquito genera. Aedes albopictus and Culex quinquefasciatus larvae were collected from natural and artificial breeding sites from Kandy and Galle districts. Fungi associated with the external surfaces and the internal organs of the collected larvae (n = 240) were cultured using potato dextrose agar (PDA). Isolated fungi were identified morphologically. Three fungal species, (Aspergillus fumigatus, A. niger, Cladosporium sp), which were common to both larval species, were used to assess the entomopathogenicity. Larval bioassays were conducted with conidial suspensions of each fungus (1×10⁷ – 1×10³ conidia mL–1), and mortalities were reported after 24 h to determine the lethal concentrations (LC₅₀ and LC₉₀). Nine fungal species were isolated from Aedes larvae, with Aspergillus fumigatus, and Cladosporium sp. were the most prominent. Twenty fungal species were isolated from Culex larvae, with A. fumigatus, Cladosporium sp, and Trichoderma sp. being the most abundant. Six fungal species, A. fumigatus, A. niger, Cladosporium sp., Curvularia sp., Fusarium sp., and Penicillium sp. were common to both Aedes and Culex larvae, while Rhizopus sp., Trichoderma sp., and Trichothecium sp. were found only from Culex larvae. Acremonium sp. was found only from Aedes larvae. Aspergillus niger showed significantly higher larvicidal activity against Cx. quinquefasciatus larvae (LC50 = 3.47×105 conidia mL–1) compared Ae. albopictus (LC50 = 7.94×105 conidia mL–1) (p = 0.0495; H = 3.86). Aspergillus fumigatus (LC50 = 1.23×106 conidia mL–1) and Cladosporium sp. (LC50 = 1.78×105 conidia mL–1) showed larvicidal activity only against Cx. quinquefasciatus. The outcomes reported a difference in the number of fungal species and the composition between Aedes and Culex larvae, with Aspergillus niger showing the strongest larvicidal effect.