|De La Torre, Theresa|
Submitted to: Sweetpotato Whitefly Progress Review Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/1/2002
Publication Date: 6/1/2002
Technical Abstract: Sweetpotato whiteflies, Bemisia tabaci (Gennadius) produce honeydew that results in cotton lint contamination causing reduced lint processing efficiency. The insect growth regulators, Applaud® and Knack®, provide effective control of SPW on cotton by interfering with their reproduction and development. We investigated their effect on SPW honeydew production. Amounts of the major sugar components of honeydew produced by adults and nymphs collected on day six following Applaud or Knack applications to cotton field plots were not significantly different compared to amounts produced by those collected from untreated plots. Similar results occurred with SPW adults confined for 48 h on Applaud or Knack < 1 to 48 h-old residues in the laboratory following cotton leaf dips. Also in the laboratory, mortality of adults was not affected by nebulizer applied contact spray applications and honeydew sugars were not significantly reduced. In contrast, mortality of first and second instar SPW nymphs on leaves was higher on day six following leaf dips in Applaud solutions compared with leaf dips in Knack or water solutions. Nymph mortality on day six following leaf-dips in Knack solutions was higher than mortality of nymphs following leaf-dips in water. Honeydew collected from nymphs during two to 50 h intervals after leaf dip treatment had reduced amounts of glucose, fructose and trehalulose, but not sucrose and melezitose per nymph compared with honeydew from nymphs on leaves dipped in water.