Size limitations in the filter chamber and digestive tract of nymphal and adult Bemisia tabaci whiteflies (Hemiptera: Aleyrodidae)

Abstract The molecular size limitations of the digestive system, including the filter chamber of immature and adult Bemisia tabaci (Gennadius) B biotype (=B. argentifolii), were studied by tracking the movement of fluorescent-labeled molecules and microspheres ingested by whiteflies. Soluble fluorescent molecules and labeled dextrans, ranging from 389 to 2,000,000 Da, were observed throughout the digestive tract of immatures 10–30 min after feeding was initiated. After removal of labeled molecules from the diet, fluorochromes were cleared from digestive system of immatures within 2 h. Fluorescent-labeled 0.1- and 0.2-μm microspheres were ingested by larvae and saturated the digestive system within 2 h after initiation of feeding. Large, 0.5-μm spheres were not observed in the digestive tract of immatures, probably because singly or as aggregates, they were too large to enter the stylet food canal. The smallest spheres examined, 0.02 μm, were not detectable in the digestive tract of immatures. Observations...