ULTRASTRUCTURE OF THE MOUTHPARTS OF ADULT SWEET-POTATO WHITEFLY, BEMISIA-TABACI GENNADIUS (HOMOPTERA, ALEYRODIDAE)

The fine structure of the mouthparts of the whitefly, Bemisia tabaci G ennadius (Homoptera: Aleyrodidae), was examined by scanning and transm ission electron microscopy. Adult whitefly mouthparts are similar to t hose of other homopterans, especially aphids, being composed of the la brum, the labium, and the stylets. The stylet bundle is the feeding or gan of the whitefly and is composed of 2 mandibular stylets and 2 maxi llary stylets. Mandibular stylets, which are located on the outer aspe ct of the stylet bundle, each contain 2 dendrites. The tips of the man dibular stylets are curved inward, and there are barb-like ridges on t he lateral aspects, which probably function in piercing and cutting pl ant tissues and in anchoring the stylets in the tissues. The maxillary stylets are not innervated and are interlocked to form 2 separate com partments, the food canal and salivary canal. At the distal end of the interlocked maxillary stylets, there is a small depression, which may allow for mixing of the salivary canal and food canal components. Mov ement of the B. tabaci stylets during feeding is discussed in comparis on with other homopterans.