Plastic cup traps equipped with light-emitting diodes for monitoring adult Bemisia tabaci (Homoptera: Aleyrodidae).

Equipping the standard plastic cup trap, also known as the CC trap, with lime-green light-emitting diodes (LED-plastic cup trap) increased its efficacy for catching Bemisia tabaci by 100%. Few Eretmocerus eremicus Rose and Zolnerowich and Encarsia formosa Gahan were caught in LED-plastic cup traps. The LED-plastic cup traps are less expensive than yellow sticky card traps for monitoring adult whiteflies in greenhouse crop production systems and are more compatible with whitefly parasitoids releases for Bemisia nymph control.

Bemisia tabaci (Homoptera: Aleyrodidae) biotype B colonization on okra- and normal-leaf upland cotton strains and cultivars.

We compared smooth-leaf okra- and normal-leaf upland cotton (Gossypium hirsutum L.) strains and cultivars for susceptibility to colonization by Bemisia tabaci (Gennadius) biotype B. Experiments were conducted at seven field sites, five at Holtville, CA, and two at Maricopa, AZ, during 1996-2000. Okra-leaf strains and cultivars, as a group, had lower numbers of adults, eggs, and nymphs compared with normal-leaf strains and cultivars indicating the potential of okra-leaf genetic traits for reducing colonization by B. tabaci. Results also suggest that okra-leaf shape may provide less favorable micro-environmental conditions for the habitat of B. tabaci because of more open canopy as evidenced by higher leaf perimeter to leaf area ratio. The okra-leaf cultivar 'Siokra L-23' appears to have genetic traits that should be examined further as a source of B. tabaci resistance.

Characterization and functions of the whitefly egg pedicel.

For the silverleaf whitefly, Bemisia argentifolii (Bellows and Perring) (Homoptera: Aleyrodidae), scanning and transmission electron microscopic techniques were used to observe the characteristics of egg oviposition into both plant cells/tissues and artificial membranes, and to document the morphology of mature egg pedicles removed from the ovaries of females. The exterior of the distal portion of the pedicel consisted of a tangled array of fibrous structures (0.2-0.3 microm in diameter) that constituted about 20-25% of the outer diameter of the pedicel. The attachments of the fibers to the core of the pedicle suggested that the pedicel functions as the collector and conduit for water (vapor), and perhaps solute movement into the egg. Silverleaf whitefly eggs on membranes were incubated at various levels of relative humidity and the eggs were scored for egg hatch. At 98-100% rh, the percentage egg hatch was 86-98%. At lower humidity ranges of 0-20, 55-65, and 75-85% rh, none of the eggs hatched. Media (solute) uptake by silverleaf whitefly egg pedicels was determined by exposing the pedicel side of eggs oviposited on membranes to media solutions containing the high molecular weight polysaccharide, [(14)C]-inulin. Solute uptake by the pedicel and movement into developing silverleaf whitefly eggs were demonstrated using [2-(14)C]-acetate, and assaying for radioactivity in hatched nymphs. These studies, using exposure of pedicels to relative humidity and radiolabeled materials, demonstrate that whitefly egg hatch is dependent upon water uptake by the pedicel, and that the pedicel has the ability to transport solutes into the developing egg.