Aerial spores of Neozygites fresenii (Entomophthorales: Neozygitaceae): density, periodicity, and potential role in cotton aphid (Homoptera: Aphididae) epizootics
1996
Steinkraus, D.C. | Hollingsworth, R.G. | Boys, G.O.
This is the first report on densities of aerial spores of a Neozygites species and one of only a few reports on field dispersal of aerial spores of an entomopathogenic fungus. Densities of primary conidia of Neozygites fresenii (Nowakowski) Batko in the air over cotton fields during epizootics in the cotton aphid, Aphis gossypii Glover showed a clear diel periodicity. Peak discharge of primary conidia occurred between 0100 and 0500 hours. Few aerial spores were present between 0900 and 2400 hours. Densities of primary conidia as high as 58,327/m3 of air were recorded at 0300 hours on 24 July 1993 during an epizootic in a commercial cotton field in St. Francis County, Arkansas. Microscope slides placed in the field to collect N. fresenii spores indicated that significantly higher spore numbers were collected 30.5 cm from the soil surface than 61, 122, or 183 cm from the surface. Capilliconidia were also present in the air, but in most cases in much lower densities than primary conidia. Rotorod samplers are relatively inexpensive, portable, and can be powered with a small battery. Rotorod samplers may be more practical than Burkard samplers for monitoring aerial spores over cotton fields, unless accurate hourly data over long periods are required.
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