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Effects of Selected Pesticides on Populations of Beneficial Arthropods in Lower Rio Grande Valley Cotton

A.N. Sparks, Jr., J.W. Norman, J.R. Raulston, D.W. Spurgeon and Billy F. Tanner


 
ABSTRACT

Comparative effects of early-season applications of azinphosmethyl, oxamyl, two rates of endosulfan, ULV malathion, and fipronil on populations of beneficial arthropods in cotton were examined in large-plot field studies. Two applications of each insecticide were applied to coincide with the normal timing of producer applications for control of overwintered boll weevils. Treatment effects were evaluated by sweep net and drop cloth samples, and collections by a tractor-mounted sampler. Few treatment effects could be statistically demonstrated after the 1st application because of generally low population levels of beneficial arthropods and absence of an untreated check. However, population trends suggested that applications reduced beneficial arthropod population levels temporarily. Analyses of second application effects indicated that all insecticides usually resulted in an immediate suppresion of beneficial populations, followed by a population recovery that appeared to be caused by immigration. Thus, choice of early-season insecticide appeared to have little influence on effects of these applications on beneficial arthropod populations. In addition, general disruption of the natural enemy complex in cotton was not achieved in field-sized treatment areas because of immigration of beneficial arthropods from surrounding areas.



Reprinted from Proceedings of the 1997 Beltwide Cotton Conferences pp. 1313 - 1316
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998