|Freeman, Thomas - NORTH DAKOTA STATE UNIV|
Submitted to: Silverleaf Whitefly Research, Action and Technology Transfer Plan
Publication Type: Abstract Only
Publication Acceptance Date: March 27, 2002
Publication Date: March 31, 2002
Citation: Freeman, T.P., Buckner, J.S., Nelson, D.R. 2002. Silverleaf whitefly nymph stylets and feeding characteristics [abstract]. Silverleaf Whitefly Research, Action and Technology Transfer Plan. p. 67. Technical Abstract: After emerging from the egg, silverleaf whitefly (Bemisia argentifolii Bellows & Perring) nymphs move across the surface of the leaf in search of a feeding site. The crawler is the only nymphal stage that is capable of locomotion. The crawler must begin feeding quickly if it is to survive. Prior to the onset of feeding the crawlers stylet is folded within the body of the nymph. When the crawler begins to feed it becomes flattened against the leaf surface. Like the adult whitefly, the nymph produces a flange like material that appears to seal] the tip of the rostrum to the surface of the host leaf. Staining techniques can be used to determine both probe and feeding sites. The nymph stylet bundle consists of a pair of mandibular stylets serrated at the tip and a pair of maxillary stylets locked together to form the food canal. The ultrastructure of the nymph and adult stylets are similar. The nymph stylet is extended through a groove in the rostrum. After penetrating the epidermal layer of the leaf the stylet moves through the apoplast of mesophyll all the way to the phloem tissue. The stylet path can be studied by examining the salivary sheath which remains in the leaf even after the stylet has been removed. The salivary sheaths are often highly branched, demonstrating that the stylet can be at least partially withdrawn and then extended in a different direction. Prior to each molt, the stylets are withdrawn into the body of the nymph and left behind in the cast exuviae. With each successive molt the stylet becomes longer and in the fourth instar may reach lengths greater than 200 um.