Figure 2.

The intricate internal structure of the whitefly plays a crucial role in facilitating the circulative transmission of plant viruses by the B. tabaci species. The virus (e) is obtained through the ingestion of phloem sap and subsequently transported to the midgut (h) using the stylet (n) and esophagus (f). In the filter chamber area (g), the virus particles successfully breach the protective barrier of the midgut and gain entry into the hemolymph (l) by crossing the midgut plasmalemma and epithelial brush border. Once in the hemolymph, the virus circulates and ultimately reaches the primary salivary glands (a). Within these glands, the virus is internalized by passing through the basal lamina and secretory cells until it reaches the central lumen, which connects to the salivary gland duct. The virus then travels through the salivary gland duct and is expelled from the body during feeding via the salivary canal. It is important to note that the accessory glands (b) do not participate in the transmission process. Some virus particles that fail to enter the hemolymph are excreted from the body along with the honeydew through the hindgut. Additionally, the virus has the ability to invade developing oocytes (j) and eggs (k), potentially resulting in its transmission to the next generation through transovarial means. Furthermore, endosymbionts (i) play a significant role in transmission by secreting GroEL into the hemolymph.