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Submitted to: Great Lakes Entomologist
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/22/1999 Publication Date: N/A Citation: N/A Interpretive Summary: This paper evaluates the ability of two fungi that have insecticidal activity to kill a destructive stage of the banded -sunflower moth. It was found that both fungi are very pathogenic to this moth and have potential as control agents for this moth. The moisture conditions that these fungi require to grow, however, may be satisfied only for those stages in the life cycle of this moth that occur in the soil. Technical Abstract: Laboratory bioassays were conducted to assess the virulence of two entomopathogenic fungi, Beauveria bassiana (Balsamo) Vuillemin, and Metarhizium anisopliae (Metschnikoff) Sorokin to 5th instars of the band- ed sunflower moth. Larvae of this pest experience similar temperatures in July and August as they develop on sunflower in the northern Great Plains. Mortality from exposure to conidia from both fungi in concentrations in the range of 10**8 and 10**7 conidia/ml was 100% in 10 days or less. Ninety percent mortality occurred over 21 to 26 days when the concentration of conidia was 10**6 conidia/ml. Concentrations of conidia from M. anisopliae for 50% mortality, ranged from about 3.6 x 10**3 at 25 deg C to about 4.1 X 10**3 at 20 deg C. The concentration of conidia from B. bassiana for 50% mortality ranged from 14.9 x 10**4 conidia/mi at 20 deg C to 6.7 x 10**3 conidia/ml at 25 deg C. The high humidities required for growth and germination may reduce the usefulness of these fungi as control agents of banded sunflower moths in the northern Great Plains. Further studies are needed to determine if there are microhabitats in the soil or on the sunflower head where the humidity is high enough for germination and growth of B. bassiana and M. nisopliae. |
