Morphological differentiation of the mouthparts between Bemisia tabaci and Trialeurodes vaporariorum reflecting feeding preferences

Bemisia tabaci and Trialeurodes vaporariorum are two destructive agricultural pests in agroecosystems, causing crop damage globally by feeding on phloem sap with their piercing-sucking mouthparts. To gain new insights into feeding preference and tructural anatomy of these two species, the fine structure of their mouthparts was observed using scanning electron microscopy. The basic mouthpart structure of both species is similar with no significant difference in the distribution, number and types of sensilla. However, six significant micromorphological characters were observed: 1) an external gap-like structure at the tip of the mandibular stylet was discovered for the first time; 2) the two thin lateral transverse ridges of the maxillary stylets of T. vaporariorum are closer together than those of B. tabaci; 3) the mandibular serrate ridge possesses mamelons only in T. vaporariorum; 4) microtrichia on the labrum are absent in T. vaporariorum and relatively conspicuous in B. tabaci; 5) microtrichia are present at the base of the first segment of the labium of T. vaporariorum but not in B. tabaci; 6) the labium is significantly longer in T. vaporariorum. New information on mandibular serration, the specific gap-like mandibular structures, and the variety of hair-like structures in both studied species are recorded for the first time. The distribution and structure of micro hairs vary within both species. The observed differences in microcharacters in two whiteflies may help better understand their feeding behavior and virus transmission by mouthparts.