|Chu, Chang Chi|
|Freeman, T. - ELE. CTR ND ST UNIV FARGO|
Submitted to: Sweetpotato Whitefly Progress Review Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 1999
Publication Date: N/A
Technical Abstract: Whitefly feeding is complex and includes the location of appropriate sites to probe leaves so that minor veins can be located. Nymphal stage survival of the silverleaf whitefly requires stylet penetration of the smallest veins in host plant leaves. Light and electron microscopy as well as confocal imaging have revealed that successful feeding always involves probing of no more than three xylem elements minor veins. A specialized saliva produces a sleeve-like salivary sheath that forms around the stylets to the minor veins. Most of the sheath material inside the leaf is extra- cellular and in the extensive air space between spongy parenchyma cells. Only a small portion of the sheath is found inside cells, that portion being in epidermal cells. We found almost no evidence of stylet or sheath penetration into parenchyma or palisade cells. Stained and cleared non- sectional leaves provide a view of entire intact sheaths which showed that nymphs that developed beyond the first instar always made contact with veins as evidenced by the presence of the salivary sheaths. Fused bead appearing sheaths were up to 140 um long and about 2 um in diameter at their widest dimension. The relative success of silverleaf whitefly on different hosts is, in part, attributable to the geometry of the feeding arrangement in relationship to the availability of minor veins in the host plants.