ABSTRACT

Techniques developed to determine the chemical composition of honeydews found on cotton fiber have been employed in an investigation to develop enzymatic methods of diminishing the sticky nature of such lint. Hot water was used to quantitatively remove honeydew from contaminated lint. Sugars so extracted were quantified as anions by gradient ion-exchange HPLC. Honeydews extracted from cotton fibers were found to be complex mixtures of sugars ranging in size from monosaccharides to polymers approximately twelve monosaccharide units in size. These complex mixtures are created from sucrose in the phloem sap of the cotton plant by transglycosylation reactions within various homopterian insects. Significant differences in composition exist between the honeydews of the various homopterian insects which attack cotton. Honeydew from the sweetpotato whitefly, Bemisia tabaci, typically contains larger amounts of the sucrose isomer trehalulose and a relatively small percentage of reducing sugars. Tests based upon copper ion reduction can therefore not be used to detect sweetpotato whitefly honeydew. Honeydew from the cotton aphid, Aphis gossyppi, is characterized by little trehalulose, a sizable melezitose component, and a predominant fraction of large molecular weight sugars. A series of enzymes were sprayed on honeydew-contaminated cotton during harvest to determine whether their stickiness could be reduced in this manner. One of the enzyme preparations investigated in this manner produced cotton with diminished reducing sugar content and minicard ratings. However, some of this reduction was determined to be due to activation of microbes on the fiber by the applied enzyme solution.