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Microstructure of Feeding in Nymphal Bemisia Argentifolii in Cotton and Cantaloupe

Allen Carson Cohen, T.J. Henneberry, Thomas Freeman, Dennis Margosan, P. Vail, Chang-chi Chu


Studies using confocal and light microscopy revealed that feeding structures of 145 attached B. argentifolii nymphs (2nd-4th instar) always reached vascular tissue in cotton and cantaloupe leaves. Analysis of stained and cleared leaves permitted detailed examination of the course of intact feeding structures (salivary sheaths) from the plant's under surface to the target tissue. Nearly every salivary sheath made complex turns and contained several branches that could be considered mistakes in the course of locating target veins. Only minor veins were found to be the targets of the whitefly nymphs. The position of minor veins were invariably associated with elongated surface cells. Although they were in contact with or close to elongated epidermal cells, all attached nymphs made mistakes in their progress towards the target bundles. Confocal microscopy revealed that the specific targets within the veins were apparently always phloem cells. This technique also showed that the sheaths often wrapped around spongy parenchyma cells on their course to veins. Once within the bundle, the sheaths often wrapped around the xylem elements and seemed always to terminate in phloem elements. Very often a single sheath that reached a minor vein would branch at the bundle into two or more (sometimes four or five) sheaths.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 740 - 743
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998