A 2-yr, multistate project was initiated in 1994 to determine action thresholds for management of Bemisia tabaci (Gennadius) Biotype B (= B. argentifolii Bellows & Perring) in cotton using chemical insecticides. Identical experimental designs and data collection protocols were used at sites in Brawley, CA, Yuma and Maricopa, AZ, and Weslaco, TX. The prescriptive application of insecticides based on 4 candidate action threshold levels (2.5,5, 10, or 20 adult B. tabaci per leaf) were compared with one another and an untreated control. In general, there were few differences in whitefly populations among action thresholds of 2.5, 5, and 10 adults per leaf at sites in Arizona and California. All insecticide treatments typically reduced population densities below those in untreated control plots. Insecticide applications were generally ineffective in Weslaco, possibly due to reduced insecticide susceptibility or the late onset of pest infestation, and there were few differences in population density among treatments. Yields were higher in sprayed treatments, but there was little difference among threshold levels. Yield differences were not detected among any treatments for Yuma and Weslaco in 1994 and for Maricopa in 1995. The levels of lint stickiness due to honeydew deposition, as measured by thermodetector, were not consistent among sites and were not generally related to pest densities in the different threshold treatments. Levels of stickiness tended to be higher in 1994. There were no treatment effects on other standard measures of lint quality. A simple budgeting analysis assuming 43.24/ha per application for insecticides and 1.59/ kg for lint suggested that action thresholds of 5-10 adults per leaf provided the highest net return at most sites.
Document Type: Research Article
Publication date: December 1, 1998
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Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.