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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVE NUTRITION FOR HONEY BEE COLONIES TO STIMULATE POPULATION GROWTH, INCREASE QUEEN QUALITY, AND REDUCE THE IMPACT OF VARROA MITES

Location: Honey Bee Research

Title: The Salivary Glands of Adult Female Varroa Destructor (Acari: Varroidae), an Ectoparasite of the Honey Bee, Apis Mellifera (Hymenoptera: Apidae)

Authors
item Cicero, Joseph -
item Sammataro, Diana

Submitted to: International Journal of Acarology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 8, 2010
Publication Date: October 29, 2010
Citation: Cicero, J.M., Sammataro, D. 2010. The salivary glands of adult female Varroa destructor (Acari: Varroidae), an ectoparasite of the honey bee, Apis mellifera (Hymenoptera: Apidae). International Journal of Acarology. Vol. 36(5):377-386.

Interpretive Summary: Varroa destructor Anderson and Trueman 2000, an ectoparasite of honey bees, causes huge economic losses to apiculture annually. Its role as a vector of diseases is thought to involve the transmission of virus through feeding on honey bees. The main avenue of transmission is thought to be from the salivary glands. The salivary glands are paired, oval organs, closely attached to the base of the mouthparts and enveloped in a sheath of unknown embryological origin. We examined the salivary glands using a Scanning Electron Microscope (SEM) and found that they are characterized by the surrounding sheath, and cells that have a strong presence of rough endoplasmic reticulum, irregular-shaped nuclei, and secretory spheres. Bacterial biofilms were found to be are associated with the spheres and the rupture. We also found virus particles and endosymbionts present in the glands. This is the first time that an SEM was used to visualize the internal organs of this mite. It has helped us to understand how the salivary glands are organized and that virus particles can be found there. The next step is to determine if pathogenic virus reside in the salivary glands of Varroa.

Technical Abstract: Varroa destructor Anderson and Trueman 2000, an ectoparasite of honey bees, causes huge economic losses to apiculture annually. Its role as a vector of diseases is thought to involve the salivary glands as the terminal organs of transmission. The salivary glands are paired, oval, non-acinar organs, closely attached to the base of the gnathosoma and enveloped in a sheath of unknown embryological origin. Ultrastructurally, they are characterized by the surrounding sheath, and cells that have a strong presence of rough endoplasmic reticulum, irregular-shaped nuclei, and secretory spheres surrounded by an otherwise electron-lucent cytosol. Secretory spheres are sparse in most peripheral cells and heavily converged about the apical membranes of interior cells. Interior cells are positioned radially about the internal duct cells. The internal ducal lumen is narrow and brush-bordered. The membranes between the ducal lumen and the gland cell cytoplasm are fused and ruptured, allowing the salivary spheres to pass into the interior duct for secretion through the exterior duct. Bacterial biofilms are associated with the spheres and the rupture. Virus particles and endosymbionts are also present in the glands. The external duct remains uncharacterized, but the assumption that its embryonic origin is the same as that of the internal duct and surrounding gland cells is questioned.

Last Modified: 9/1/2014
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