Pathogenicity of isolates of entomopathogenic fungi against spodoptera frugiperda (Lepidoptera: Noctuidae) and Epilachna varivestis (Coleoptera: Coccinellidae)

In order to obtain native isolates of entomopathogenic fungi in Durango, Mexico, with pathogenicity against Spodoptera frugiperda Fall Armyworm and Epilachna varivestis Mexican Bean Beetle, main pests of maize and beans, respectively, 97 isolates were evaluated, Bb42 and Bb18 of Beauveria bassiana and Ma91 of Metarhizium anisopliae. A bioassay using neonate larvae under completely randomized design of treatments per dose (ANOVA) and Tukey's test were use to measure the insecticidal activity in both insects, mortality data were used to calculate LC₅₀ and LT₅₀. The isolation Bb42 obtained from larvae of S. frugiperda and evaluated against second instar larvae of the same insect showed the highest virulence 96.6% of mortality to rate of 1x10⁹ spores mL^-1, with LC₅₀ of 5.92x10³ spores mL^-1, and lethal time of 3.6 days; isolation Bb18 from beans was highly virulent against neonate larvae of E. varivestis, 93.3% of mortality to 1x10⁹ spores mL^-1 with an LC₅₀ of 1.20x10⁶ and lethal time of 5.1 days (Tukey, p ≤ 0.05). In conclusion, the pathogenicity of the isolates was greater when were obtained directly from the insect hosts than from maize and beans soil samples, as well as when it's are obtain from their respective host culture where was find the pest insect.