Submitted to: Sweetpotato Whitefly Progress Review Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2000
Publication Date: N/A
Technical Abstract: Specific enzymes mediate many of the interactions between the silverleaf whitefly and its host plant. Two whitefly enzymes, alkaline phosphatase and sucrase, have been localized and their potential roles will be discussed. Alkaline phosphatase (ALP) was initially detected in fixed and paraffin-embedded whitefly sections. The most prominent activity is associated with primary salivary glands and could be detected with both colorimetric and fluorescent ALP substrates. Additional activity was detected in accessory salivary glands, salivary ducts, the cibarium and mouth, regions of the oviduct surrounding the terminal oocyte, the colleterial gland, and occasionally within the midgut. Salivary ALP was obtained by collecting and concentrating sucrose diet from whitefly feeder units. Optimal ALP activity was found between pH 10-10.5. Possible functions of whitefly ALP may include a role in nutrient uptake or sclerotization of whitefly structures such as the salivary sheath. Sucras plays a key role in the flow of energy from the plant to the insect. Sucrose, the major constituent of cotton sap, is converted to glucose and fructose which are utilized by the whitefly or excreted in honeydew. The enzyme sucrase has been localized in the esophagus and midgut using a precipitating colorimetric substrate. However, the greatest concentration of activity was found in the filter chamber region along the coiled section of the midgut.