Bemisia argentifolii colonization, vascular bundle depth relationships, lint yield, and nymphal parasitism in selected deltapine cotton cultivars

Deltapine cotton cultivars are widely accepted for commercial production in the desert southwestern region of the United Stales. They also are good re productive hosts for the silverleaf whitefly, Bemisia argentifolii Bellows and Perring (Homoptera: Aleyrodidae). This paper reports results of studies conducted to determine the relationship between depth of leaf vascular bun dles from underleaf surfaces and B. argentifolii colonization. We also dete rmined the effect of cotton cultivar on B. argentifolii nymphal parasitism and effects of B. argentifolii population densities on cotton yield and lin t stickiness. Results showed that the distance from cotton underleaf surfac es to the center of minor vascular bundles was negatively related to whitef ly adult and nymphal densities on cotton. This leaf character is important for breeding and selection of resistant varieties because the deeper minor vascular bundles may be beyond the reach of the stylets of first instars. P ercentages of the nymphs parasitized were significantly different among tes ted cultivars indicating the potential for reducing whitefly colonization b y breeding varieties that are more attractive to parasites, although percen tages of nymphs parasitized were not correlated with numbers of adults, egg s, and nymphs. Cotton yields decreased with increasing whitefly populations , Cotton line stickiness increased with increased whitefly populations.