Investigation of effectiveness of native entomopathogenic fungi against the fall webworm (Hyphantria cunea Drury)

Hyphantria cunea is one of the most important pest insects causing significant damage in many plant species. Beauveria bassiana and Metarhizium anisopliae are among the most important entomopathogenic fungi. The present study aimed to evaluate the insecticidal activity of isolates of B. bassiana and M. anisopliae against H. cunea larvae under laboratory conditions. B. bassiana isolates YK11, YK14, YK16, YK23 and YK26, and M. anisopliae isolates YK38, YK41, YK43, YK44 and YK45 were sprayed onto the 1st, 2nd, 3th, 4th and 5th instars larvae of H. cunea at the respective doses of 105, 106 and 107 spore/mL and monitored during the 10 days. All B. bassiana isolates caused 100% mortality on 1st instar larvae at the all doses. M. anisopliae isolates caused to mortality ranging from 93.33% to 79.63% on 1st instar larvae at the 105 spores/mL dose, and this ratio reached to 100% at the other doses. B. bassiana isolates showed mortality ranging from 100% to 86.30% on 2nd instar larvae at 105 spores/mL dose and mortality reached to 100% at other doses. M. anisopliae isolates showed mortality between 100% and 89.63% on 2nd instar larvae at the highest dose. While all B. bassiana isolates showed 100% mortality at the highest dose in 3th instar larvae, this ratio varied between 100%-89.63% and 90%-70% for 4th and 5th instar larvae, respectively. In the M. anisopliae isolates, the lethal effects were between 100%-81.75%, 96.67%-75.19% and 76.67%-60.00% for the 3rd, 4th and 5th instar larvae, respectively. The results showed that B. bassiana and M. anisopliae could be evaluated in the controlling of H. cunea. It would be appropriate to choose early larval instars in the struggle.