Infection of sentinel cotton aphids (Homoptera : Aphididae) by aerial conidia of Neozygites fresenii (Entomophthorales : Neozygitaceae)

Uninfected adult Aphis gossypii (Homoptera: Aphididae) apterae (sentinel ap hids) on cotton leaves were exposed for 8 h to the air over a commercial co tton field in Louisiana during the night of 1-2 July 1995. At 0015 h there were 90,437 primary conidia/m(3) air of the fungus Neozygites fresenii (Ent omophthorales: Neozystaceae) at the midfield position as determined from Ro torod samples. Forty-eight percent (n = 106) of the sentinel aphids exposed for 8 h at midfield were infected by aerial conidia of N. fresenii. Exposu re of sentinel aphids outside the cotton field, at 10 and 100 m downwind an d 10 m upwind, resulted in 34.8% (n = 131), 24.0% (n = 129), and 17.4% (n = 146) infected aphids, respectively. These data demonstrate that wind-dispe rsed aerial conidia of N. fresenii are infective and rapidly and efficientl y disperse the pathogen throughout aphid populations within and between fie lds. (C) 1999 Academic Press.