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Survey and Evaluation of Native and Released Predators of the Banks Grass Mite (Acari: Tetranychidae) in Corn and Surrounding Vegetation
M. T. Messenger, L. L. Buschman and J. R. Nechols
Journal of the Kansas Entomological Society
Vol. 73, No. 2 (Apr., 2000), pp. 112-122
Published by: Kansas (Central States) Entomological Society
Stable URL: http://www.jstor.org/stable/25085951
Page Count: 11
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Surveys were made in southwestern Kansas to identify and establish relative abundances of predaceous arthropod species associated with the Banks grass mite (BGM), Oligonychus pratensis (Banks), in field corn and in the surrounding vegetation. A two-year experiment also was done to determine whether the release in the spring of commercially produced predatory mites (Acari: Phytoseiidae) in grasses adjacent to corn field borders would enhance BGM suppression over that in corn fields where no predators were released. In 1996, the release of Neoseiulus fallacis (Garman), Neoseiulus californicus (McGregor), and Galandromus occidentalis Nesbitt in roughly equal proportions at a ratio of 1 predator per 24 BGM did not significantly reduce pest mites compared to control fields. Releases in 1997 of only N. californicus at a 1:1 predator to prey ratio also did not have a significant impact on BGM populations. Berlese samples in corn and in alternate hosts 2 weeks after release failed to recover N. californicus or G. occidentalis in experimental fields, and neither predator occurred naturally in control (nonrelease) fields. Neoseiulus fallacis was recovered in both release and control fields in 1996 and 1997, but could not be distinguished from native populations. In addition to N. fallacis, four other species of naturally occurring phytoseiids were collected: Neoseiulus comitatus (DeLeon), Neoseiulus setulus (Fox), Proprioseiopsis ovatus Garman, and Amblyseiella setosa Muma. All five phytoseiids were recovered in corn and in alternate host vegetation. However, N. fallacis was the most abundant phytoseiid in corn and its population densities were significantly correlated with BGM populations. The insidious flower bug, Orius insidiosus Say (Hemiptera: Anthocoridae), was also a relatively abundant predator in corn, but its populations were not significantly correlated with those of the BGM. Several other species of predators suspected to attack BGM are reported.
Journal of the Kansas Entomological Society © 2000 Kansas (Central States) Entomological Society