Natural Prevalence, Molecular Characteristics, and Biological Activity of (Farlow) Isolated from (J. E. Smith) Larvae in Mexico.

Entomopathogenic fungi have been considered potential biological control agents against the fall armyworm (J. E. Smith), the world's most important pest of maize. In this study, we evaluated the natural infection, molecular characteristics, and biological activity of (Farlow) isolated from larvae of this insect, collected from maize crops in five Mexican locations. Natural infection ranged from 23% to 90% across all locations analyzed. Twenty-four isolates were evaluated on second instars at a concentration of 1.0 × 10 conidia/mL, causing 70% to 98.7% mortality and 60.5% to 98.7% sporulation. Isolates T9-21, Z30-21, PP48-21, and L8-22 were selected to determine their phylogenetic relationships by gene analysis and to compare median lethal concentration (CL), median lethal time (LT), and larval survival. These isolates were grouped into three clades. The T9-21, PP48-21, and J10-22 isolates were closely related (clade A), but phylogenetically distant from Z30-21 (clade B) and L8-22 (clade C) isolates. These genetic differences were not always reflected in their pathogenicity characteristics since no differences were observed among the LC values. Furthermore, isolates T9-21, J10-22, and L8-22 were the fastest to kill larvae, causing lower survival rates. We conclude that native isolates represent an important alternative for the biocontrol of .