Vitellin of the sweet potato whitefly, Bemisia tabaci: biochemical characterization and titer changes in the adult.

SDS-PAGE of the sweet potato whitefly (Bemisia tabaci) egg extract showed one major band (approximately 190 kDa) and two minor bands (approximately 75 kDa and 67 kDa). A distinct 190 kDa band was also present in male extract. On SDS gels the vitellin band of the greenhouse whitefly (Trialeurodes vaporarium) was larger, about 220 kDa. The native molecular mass of sweet potato whitefly vitellin was estimated to be 375 kDa using 4-20% native porelimiting gel electrophoresis. Its isoelectric point was estimated to be 7.3 using isoelectric focusing. Two-dimensional gel electrophoresis and densitometry were used to estimate vitellin subunit composition; the data suggest that the sweet potato whitefly vitellin is likely to be a 380 kDa native molecule formed by two 190 kDa subunits. The two minor bands (75 kDa and 67 kDa) may be breakdown products of the native vitellin. This conclusion was supported by a Western blot of an SDS-PAGE gel of partially degraded female and egg extracts, which showed that polyclonal antiserum raised against the 190 kDa polypeptide recognized the 75 kDa and 67 kDa bands. Seven hybridoma cell lines secreting monoclonal antibodies against the 190 kDa band were screened, and one of them (S1A2G9H2) was mass produced. The antibody recognized the 190 kDa band in a Western blot. All the screened monoclonal antibodies were female and egg-specific by ELISA and/or Western blot, suggesting that the 190 kDa band in male extract was not a vitellin. A sensitive ELISA was established that could detect as little as 1/40 of an egg equivalent of vitellin using the monoclonal antibody from S1A2G9H2. Profiles of female sweet potato whitefly reproductive activities (egg laying, amount of vitellin in the female, and total vitellin produced by a female) within 2 days after eclosion were determined. Arch. Insect Biochem.

Histological examination of flight muscle development and breakdown in Bemisia tabaci (Homoptera: Aleyrodidae): Relationship to age and flight behvior.

Bemisia tabaci exhibited their longest flights between 3 and 5 days following adult eclosion. They rarely engaged in flight when they were < 4 hr old and were only capable of short-duration flights after day 7. This difference in flight capacity appears to be associated with changes in the flight musculature and mitochondria. Myofibrils and mitochondria accounted for approximately 50% and 33% of the area within the flight muscles, respectively. These two elements, however, varied with the age and sex of the whitefly. The percentage of the total area occupied by myofibrils was lower in 9-day-old males relative to females and all other age categories. Sarcomere length decreased in older whiteflies, regardless of the sex. Myofibril diameter did not vary with the age of the whitefly, but the diameter of female whitefly myofibrils was greater than the diameter of male whitefly myofibrils. The number of myosin filaments within a myofibril unit increased with age, peaking at 5 days of age for females and 7 days of age for males. In all age groups, females had more myosin filaments than were found in males. Changes in mitochondria and levels of glycogen were related to the observed differences in flight activity. The area occupied by mitochondria was small in < 4-h-old and 9-day-old whiteflies, and mitochondrial cristae were undeveloped in newly emerged whiteflies. In 7- and 9-day-old whiteflies the cristae began to separate, leaving visible spaces within the mitochondria. Glycogen granules were abundant in the flight musculature of newly emerged (< 4-hr-old), 1-day-old and 3-day-old whiteflies, but by 5 days of age only 25% of whiteflies contained glycogen granules. Seven- and 9-day-old whiteflies contained no visible glycogen. An examination of the flight muscle of whiteflies after flights of varying duration (up to 60 min) revealed no relationships between flight duration and the number of mitochondria or the percentage of the total area occupied by mitochondria. There was, however, a positive relationship between flight duration and the percentage of total area occupied by myofibrils. © 1995 Wiley-Liss, Inc.

High Performance Liquid Chromatography Analysis of Carbohydrates of Cotton-Phloem Sap and of Honeydew Produced by Bemisia tabaci Feeding on Cotton.

Phloem sap from cotton (Gossypium hirsutum L.) was collected from young and mature leaves by the aphid-stylet technique. Exudate was analyzed for carbohydrates by HPLC using sensitive pulsed amperometric detection. The predominant carbohydrate present (>90%) was identified as sucrose. A second, unidentified compound that was not one of the more commonly translocated sugars was detected in mature leaves. Carbohydrates in honeydew produced by the sweet-potato whitefly (Bemisia tabaci [Genn.]) feeding on cotton were sucrose, glucose, fructose, trehalulose, and a series of oligosaccharides.