Isolation of Leptolegnia chapmanii, an entomopathogenic oomycete, from Misiones, Argentina: a promising tool for vector mosquito control

Abstract

Leptolegnia chapmanii (Saprolegniales, Leptolegniaceae) is an entomopathogenic oomycete with notable potential for mosquito larval control. This study investigated its natural occurrence in water bodies across Misiones Province, Argentina. Using the ‘insect bait’ method, nine highly virulent isolates were obtained from the northern, central, and south- ern regions of the province, alongside isolates of less virulent oomycetes. Iterative infection of healthy lar- vae with previously infected ones improved pathogen recovery, highlighting the method’s effectiveness in field studies. Taxonomic identification combined morphological and molecular analyses with patho- genicity assays on Aedes aegypti larvae. The findings reveal the ecological distribution of L. chapmanii and related oomycetes in Misiones, emphasizing the role of molecular tools and pathogenicity assays in their identification. This study advances the understanding of oomycete diversity and confirms their potential for mosquito control programs.